PLANING BOAT WITH TWO VORTEX GENERATORS

Description

REFERENCES CITED

U.S. Patent Documents

2,126,304	August 1938	Apel et al.
2,296,977	September 1942	Brien
2,474,667	June 1949	Harvey
2,909,140	October 1959	Kiekhaefer
2,989,939	June 1961	Tatter
2,995,104	August 1961	Mills
3,075,488	January 1963	Wolfe et al.
3,094,962	June 1963	Goar
3,126,856	March 1964	Fuller
3,148,652	September 1964	Canazzi
3,160,134	December 1964	Hillman et al.
3,363,598	January 1968	Mortrude
3,424,120	January 1969	Koriagin
3,602,179	August 1971	Cole
3,648,640	March 1972	Granger
3,807,337	April 1974	English et al.
3,966,869	December 1976	Hadley
4,237,810	December 1980	Westfall
4,644,890	February 1987	Lott
4,655,157	April 1987	Sapp
4,748,929	June 1988	Payne
4,924,792	May 1990	Sapp
4,944,240	July 1990	Morris
6,164,235	December 2000	Hoppe
6,216,622 B1	April 2001	Lindstrom et al.
6,345,584 B1	February 2002	Mascellaro
7,418,915 B2	September 2008	Campbell
10,189,544 B2	January 2019	Brizzolara et al.

Other References

• 1. Sighard F. Hoerner, “Fluid-Dynamic Drag”, (1965).
• 2. I. T. Egorov and V. T. Sokolov, “Hydrodynamics of High Speed Vessels”, Sudostroenie, 384 pages, (1965).
• 3. Eugene P. Clement, “The Planing Characteristics of a 15-degree Deadrise Surface with Circular-Arc Camber”, R&D Report 2298, Hydrodynamics Lab., David Taylor Model Basin, Washington D.C., 30 pages, (1966).
• 4. Eugene P. Clement, “How to Design an Efficient Stepped Planing Boat (Dynaplane Boat)”, 65 pages, (2006).
  • 20 Claims, 17 Drawing Sheets

FIELD OF THE INVENTION

The present invention relates to designs of vehicles at least partially supported in motion by fluid dynamic forces generated by three dynamic lift surfaces and, more specifically, the invention is intended for reduction of hydrodynamic resistance and improvement in efficiency of planing boats or vehicles moving along the water surface at speeds corresponding Froude numbers based on displacement (Fr_D) of about or in excess of 3, through utilization of the effect of the tip vortices-induced ascending flow in the gap between two parallel-moving planing surfaces by means of specific relative angular and spatial arrangement and configuration of three cambered planing surfaces.

PRIOR ART

As the Prior Art of the present invention there should be considered relevant previously developed designs of planing boats, i.e. the boats moving at Froude numbers based on displacement:

Fr D = V / ( g · D 1 / 3 ) 1 / 2 - of ⁢ about ⁢ or ⁢ in ⁢ excess ⁢ of ⁢ 3 ,

• • where:
  • V—speed of the boat;
  • D—displacement of the boat;
  • g—acceleration of gravity,
  • and supported in motion at operational speed by planing surfaces skimming along the surface of water (in contrast to submerged hydrofoils, e.g.), which planing surfaces generate dynamic lift by means of only positive hydrodynamic pressure on their facing downward wetted surfaces and characterize by positive angles of incidence relatively the surface of oncoming water flow determined by the position of leading and trailing edges, providing that the trailing edges of said wetted surfaces arranged lower than the leading edges of said wetted surfaces relatively the local level of water surface.

In particular, there should be considered hydrodynamic designs of planing boats with profiled cambered planing surfaces representing the object and essence of the present invention and having much greater potential for efficiency gains compared to conventional boats with flat (not profiled) bottom surfaces (constituting nearly all of existing boats).

This area of the Prior Art defines planing boats, as opposed to boats supported by conventional submerged hydrofoils, characterized by double-sided lifting surfaces that generate dynamic lift through increased hydrodynamic pressure on the underside and, predominantly, low hydrodynamic pressure on the upper side, which determines their drawbacks such as:

• • a limited range of operational speeds caused by cavitation (especially for deeply submerged hydrofoils);
  • bulky design and deep draft, inherent in all types of hydrofoils and, in particular, deeply submerged ones, which do not have self-stabilization and require automatic systems for stabilized motion, while their excessive draft forces the use of folding and retractable designs, which significantly increases the complexity and cost of such hydrofoil systems and creates inconvenience of their operation;
  • limited seaworthiness due to air breakthroughs to the upper low-pressure surface (which applies primarily to shallow-draft hydrofoils) resulting in loss of lift and downfalls with loss of speed and dive accelerations in rough seas, etc.

That is, all those disadvantages that the subject of the present invention—as a planing design—is devoid of.

Submerged supercavitating hydrofoils, which use only positive hydrodynamic pressures on their lower surfaces to generate lift and potentially could overcome the cavitational speed limit barrier, are also excluded from the Prior Art, since while maintaining such disadvantages of conventional hydrofoils as bulkiness and large draft, employment of supercavitating hydrofoils leads to a significant (two to three times) drop in hydrodynamic efficiency.

Hydrofoils with ventilated profiles can improve efficiency somewhat, but require an air supply system to supply atmospheric air to the submerged elements of such hydrofoils (blunt trailing edges, for example).

Further on, the essence of the present invention is to use the effect of formation of specific flow generated by a couple of counter-rotating vortices shedding from inner edges of two parallel-moving planing surfaces in the gap between these two surfaces that results in ascent of the flow downstream of said gap.

Such hydrodynamic effect can be implemented and utilized first of all on the boats of the “three-point design” featuring the two forward planing surfaces set apart relatively the boat's center plane and one aft planing surface positioned downstream the gap, that could be potentially realized, for example, by means of a boat's hull provided with two sponsons arranged transversally on the port and starboard sides at the forward part of bottom.

There could be found numerous designs of planing boats provided with two side sponsons. However, to our best knowledge none of the embodiments of these designs implies the use of the aforementioned vortex-generating/flow-ascending effect.

Analysis of the Prior Art shows that in most of these designs side sponsons are typically used to improve lateral stability (both static in displacement mode and dynamic in motion) or to enlarge the usable deck area at the bow.

On straight courses at operational planing speeds sponsons of such boat designs often come out of the water and do not affect the hydrodynamic characteristics of the boat. That is, in fact, from a hydrodynamic point of view, such hull designs are not different from a conventional single-keel dihedral motor boat, which is confirmed by quite ordinary values of hydrodynamic efficiency (weight to drag ratio), which do not differ from conventional sponson-less boat designs.

Another group of designs featuring sponsons relates to the hydroplane configuration, which has its origins in the Apel design, developed back in the 1930s.

The Apel hydroplane design involves aerodynamic forces to keep the hull mostly slightly above the water and thereby reduce hydrodynamic drag, and so although at high speed it has some performance advantages over conventional planing boats, its use is limited to racing boats due to potential aerodynamic instability and poor seaworthiness caused by the basically flat bottom.

Correspondingly, such flat bottom surfaces in the aft part of hulls of Apel hydroplanes do not conform to the profile of the water surface downstream the gap between the sponsons and do not presuppose the use of an ascending flow effect, which in some subdued form could be generated by their flat-bottomed sponsons.

These flat surfaces of Apel hulls are due to meet the required aerodynamic properties of this design, but at the same time they are the source of their inherent problems.

Hydroplane designs can only be conditionally classified as a “three-point type” since riding at high speed they are supported predominantly by aerodynamic lift forces while only two front sponsons could barely touch the water and the after-body supposed to be supported by the dynamic forces generated by a propeller and aerodynamic forces. That is, in the conceived mode of motion at high speed, the Apel-like hydroplane boats actually form a dynamic air cushion under the hull and fly, while the aft part of the hull should not touch water at all, which does not necessitate the use of any special hydrodynamic effects.

As a result one of the key problems of the Apel-like designs, explaining why they have not found widespread use and are used only as racing boats, is the inherent aerodynamic instability in the form of divergence, caused by the typical location of the center of pressure of the aerodynamic forces of this hull design ahead of the center of gravity, which results in the tendency to tip over the stern (happening regularly during racing).

Compared to hydroplane boats of the Apel design, the design of this invention does not rely on aerodynamic forces, provides dynamic stability, seaworthiness and higher hydrodynamic efficiency over a wide speed range (not to mention operational safety).

Accordingly, improvement of hydrodynamic efficiency due to the conformity of the aft surface to the peculiarities of the flow induced by vortex generation on the sponsons is not reflected in the known samples of hulls based on the Apel scheme and there are no known signs related to any design of Apel hydroplane boats that deliberately use forward planing surfaces to generate counter-rotating vortices between them and the specific position and configuration of the aft planing surface to exploit the effect of ascending flow.

The hydrodynamic systems with the split and set laterally apart forward dynamic lift surfaces and a single center plane-arranged aft dynamic lift surface can be found also in the Prior Art both in application to hydrofoils (U.S. Pat. No. 6,164,235, e.g.) and boats dynamically supported by planing (supposedly flat and not cambered) surfaces (U.S. Pat. No. 4,748,929, e.g.).

However none of them show signs of trying to use beneficially the effect of the ascending flow generated by inner tip vortices of the forward split dynamic lift surfaces in order to reduce resistance of the aft surface by means of its proper configuration and vertical and angular arrangement (conforming the slope and shape of ascending flow), and doesn't provide any specific requirements that determine the optimal spatial and angular relative arrangement of the three dynamic lift surfaces (and, moreover, cambered ones) that could utilize this effect and ensure the minimum hydrodynamic drag and maximum efficiency of the boat, which is exactly the essence of this invention.

The most effectively this invention can be realized in the case of cambered planing surfaces.

With regard to the use of cambered planing surfaces in the designs of the Prior Art, it should be noted that although their hydrodynamic characteristics can be significantly superior to those of flat planing surfaces, it's problematic for a single cambered planing surface to maintain the optimal trim. So there is no guarantee that such a single surface will perform optimally and will most likely be prone to dynamic instability, which calls into question their direct practical use in this configuration.

In this connection, it is natural that the cambered planing surfaces of the Prior Art are used in stepped hull designs featuring additional aft lifting surface, which fixes the trim of the boat and angular position of the forward cambered planing surfaces relative to the water surface.

However, such configuration has an inherent disadvantage, leading to a decrease in hydrodynamic efficiency:

When moving along the surface of the water, the forward planing surface generates a deformation of the water surface in the form of a wave trough characterized at typical sizes and speeds of planing boats by a descending flow. Therefore, in order to develop the necessary lifting force, any lifting surface placed aft in the wake of the front surface in the said wave trough has to be installed at a higher trim angle, which leads to increased hydrodynamic resistance and a decrease in the hydrodynamic efficiency of this hydrodynamic design as a whole.

In contrast, the aft planing surface of the present invention using the ascending flow effect reduces hydrodynamic resistance and not impairs, but improves the overall efficiency of this hydrodynamic design, which, as a consequence, ceteris paribus, for typical sizes and speeds of planing boats, will always exceed the efficiency of stepped hull designs.

As a result, the configuration featuring two forward cambered planing surfaces and one aft cambered planing surfaces corresponding provisions of the present invention provides dynamic stability of this design not deteriorating, but improving hydrodynamic efficiency of the boat.

Analysis of the Prior Art revealed no signs of using the effect of counter-rotating vortices and ascending flow generated by two parallel-moving planing surfaces constituting the principal point of the present invention.

An indicator of the lack of analogues is the fact that the analysis of the Prior Art did not reveal any signs of the proper spatial and angular relative position of the forward and aft cambered planing surfaces and endowing the aft surface with the configuration with gradually increasing from the center to the periphery deadrise angles and moduli of negative angles of incidence, leading to half-planes being curved upward and twisted down in a substantially hyperbolic manner, which would involve taking into account the real features of the ascending flow and the deliberate intention to use these features to reduce hydrodynamic resistance and improve the efficiency of a planing boat or vehicle.

Consequently summing up it can be concluded that none of known designs of the Prior Art uses the aforementioned effect.

Thus, the hydrodynamic design of the present invention has no analogues and compares favorably with the Prior Art. It allows the use of highly efficient cambered planing surfaces while maintaining dynamic stability and providing the highest efficiency being superior to the known hydrodynamic designs of the Prior Art.

BACKGROUND OF THE INVENTION

One of the main tasks of developing planing boats—like other vehicles—is to increase their efficiency (fuel efficiency, e.g., which finally can be reduced to such characteristic as, e.g., weight to drag ratio) resulting in a higher speed and/or reduction in power requirements and fuel consumption, longer range, lower specific emissions, higher payload, etc., Accordingly, the cardinal way to improve efficiency of boats is to reduce hydrodynamic resistance, which includes two principal components: —resistance of form and frictional resistance.

The former—resistance of form—depends on the angular position of planing surface relatively the flow (in inverted setting): The higher angle—the higher dynamic lift of this planing surface supporting the boat in motion, the smaller required wetted area and corresponding frictional resistance, but higher resistance of form.

On the other hand reducing the angle leads to lower resistance of form, but this reduces also dynamic lift force, so that to keep the required dynamic support the wetted area should be enlarged resulting in higher frictional resistance.

Accordingly, the goal of improving efficiency is to minimize the combination of the resistance of form and friction resistance, and, ultimately, to minimize both components simultaneously.

One of the solutions in this direction is to provide the planing surface with a concave profile, which makes it possible to significantly increase the lifting force without enlarging the wetted surface and increasing the friction resistance. In this case, the leading edges of the profile may have very small angles of incidence relative to the free surface of the water, which minimizes the resistance of spraying.

In combination with this, changing the angular position of the concave (cambered) profile by tilting it down (nose-dive)-without rise of frictional resistance and without reducing the lift-would realize the ultimate way to increase the efficiency of the boat. This opportunity is provided in case of using the hydrodynamic effect generated by two parallel-moving planing surfaces: Two planing surfaces set apart transversely to the direction of motion form in the gap between their inner (facing each other) edges and downstream the flow an ascending flow representing the initial part of the wave disturbance of the water surface developed by operation of these planing surfaces.

The nature of the ascending flow is associated with counter-rotating tip vortices shedding from the inner edges of the two planing surfaces and caused by the flow of water over the edges up from the high pressure zone on the bottom working side of the planing surface to the lower pressure zone beyond the edges of planing surfaces. Such tip vortices rotate masses of water relatively the axis following along the principal flow and propagate this disturbance downstream the flow.

The direction of rotation of the tip vortex generated at the inner edge of the right-hand planing surface is clockwise, and the left one is counterclockwise, when viewed from the front.

Thus, these counter-rotating vortices generate a velocity field in the gap between planing surfaces with a velocity component directed upwards, which creates an ascending flow behind these planing surfaces, rising above the undisturbed water level and inclined to this level at some negative angle (which disturbance further downstream transforms into dissipating wave motion of the water surface).

So, any planing surface arranged amid this gap in the projection to the transverse to the flow plane and somewhat aft of the mentioned parallel-moving planing surfaces could be inclined nose-dive and this way positioned more favorably in terms of reduction of the resistance of form, maintaining at the same time some proper angle of incidence relatively the local oncoming ascending flow in order to generate required lift and without any increase in frictional resistance. That ultimately leads to a decrease in resistance and improvement in efficiency of such hydrodynamic system and the boat in general.

The essence of this effect is as follows:

In the case of placement of the aft planing surface within the range of ascending flow inclined at some negative angle to the undisturbed water level, the directed generally upward vector of the total force of dynamic reaction of water on the aft planing surface (which keeps the required angle of incidence relatively the inclined ascending flow) will be tilted forward in the direction of movement of the boat by the angle corresponding to the angle of slope of the ascending flow at the location of the aft planing surface.

As a result, the directed backwards projection of this total vector onto the horizontal plane (i.e., the vector of hydrodynamic resistance force) decreases and even can change its sign (in the case of highly efficient/low drag planing surface and high angle of slope of the ascending flow). Or, putting it another way, the new direction of the total dynamic reaction force vector produces (compared to the same aft planing surface but skimming along the undisturbed water level) an additional forward-looking component of force (similar to some additional thrust) that, in turn, reduces drag and increases the hydrodynamic efficiency of the boat.

That is, in this way the aft planing surface actually recovers some part of the energy spent by the forward planing surfaces to disturb the incoming water flow and to deviate the masses of water upwards relatively the level of undisturbed water surface in the form of generation of the ascending flow.

Such hydrodynamic effect can be realized and favorably utilized in the case of the three-point design presupposing, for example, two planing surfaces arranged transversally on the port and starboard sides in front part of the boat, forward of the center of gravity, and one central planing surface positioned aft of the center of gravity of the boat (i.e., its center of dynamic pressure should be positioned aft of the center of gravity of the boat).

The above double dynamic support of the boat by lifting forces located upstream and downstream of the center of gravity practically ensures dynamic stability of the boat in contrast to the hydrodynamic configuration based on a single dynamic lift surface positioned under the center of gravity. The same applies to conventional planing boats with a single dynamic lift bottom surface offset to the transom, which, at optimum angles of incidence from the point of view of minimum drag and high efficiency, are prone to such a type of dynamic instability as porpoising and operate overwhelmingly at not optimum but more stable trim angles and, so, at not optimum and higher drag angles of incidence of bottom planing surfaces.

Full maximum possible efficiency of the hydrodynamic design comprising two vortex-generating forward surfaces and one aft surface washed by the ascending flow can be achieved only in the case of proper positioning and shape of the aft planing surface.

As far as the aft planing surface should correspond to the ascending flow generated by the forward planing surfaces, its optimum position should be determined by such principal factors of formation of the ascending flow as the intensity of the vortices (being the function of the lift coefficient and, so, the camber line of the forward surfaces, and the width of the gap) and the position of the aft planing surface relatively the forward ones, and, more specifically, by the spatial offset and angular positions of hydrodynamic base lines of cambered profiles of the vertical along the flow sections of the aft planing surface relatively the positions of hydrodynamic base lines of cambered profiles of the forward planing surfaces.

In the vertical sectional along the flow view the hydrodynamic base line of cambered profile represents the line or axis that serves as a basis for offsets along the chord, which determine the contour of the profile.

As an example, in the case of the well-known Virgil Johnson profile the hydrodynamic base line is the reference line for the offsets provided by the equation determining the Johnson three-term camber curve:

h = b · C L , d · ( - 20 ⁢ X 3 / 2 + 8 ⁢ 0 ⁢ X 5 / 2 - 64 ⁢ X 5 / 2 ) / 7.5 π ,

• • where:
  • b—chord length of the camber curve;
  • C_L,d—two-dimensional design lift coefficient for a cambered planing surface;
  • X=x/b; where: x—abscissa along the chord of the profile.

For the purpose of maximizing hydrodynamic efficiency, the aft planing surface should be positioned and configured to match the 3-dimentional shape of the water surface of the ascending flow generated by the forward planing surfaces downstream of their trailing edges, while parameters of this 3-dimentional shape could be obtained, e.g., through CFD analysis or model tests.

At the same time the parameters of the ascending flow can also be evaluated from formulae derived for the velocity field generated by two parallel counter-rotating vortex cords spaced apart in a flow at some distance from each other (representing cords of the tip vortices shedding to the free flow from the inner edges of the forward planing surfaces).

The joint operation of the two counter-rotating vortex cords spaced apart symmetrically relatively the Center Plane results in an “upwash” within and at some distance behind the gap with the following vertical component of velocity for each vertical longitudinal section of the flow:

ω = 2 ⁢ C L · V · b · B / π · ( B - 2 ⁢ x ) · ( B + 2 ⁢ x ) ,

• • where:
  • x—is the distance from the Center Plane;
  • B—is the width of the gap between the inner edges of the two forward planing surfaces;
  • b—chord of the forward planing surface;
  • V—velocity of flow (speed of motion);
  • C_L=2 L/ρ·V²·A—lift coefficient of the forward planing surface;
  • L—lifting force of the forward planing surface;
  • ρ—mass density of water;
  • A—wetted area of the forward planing surface.

Consequently, the angle of elevation of the slope of the ascending flow corresponding to the angle of the “upwash” relatively the undisturbed water level for each vertical longitudinal section of the flow β=arc tg(ω/V) can be found:

β = arctg [ 2 ⁢ C y · b · B / π · ( B - 2 ⁢ x ) · ( B + 2 ⁢ x ) ] .

As an example, for a chord of forward planing surfaces (generating counter-rotating vortices) equal to b=0.5 m, the width of the gap B=2 m and the lift coefficient of the forward planing surface C_L=0.3, the angle of elevation of the slope of the ascending flow at the Center Plane will be equal β=2.73°, while with increasing distance from the central plane, the angles of elevation grow hyperbolically.

For the ordinate of the rise of the ascending flow relatively the undisturbed water level not far aft of the forward planing surfaces:

y = d · tg ⁢ β ,

• • where: d—distance between the upstream points of the inner gap-forming edges of the forward planing surfaces and sections of the aft planing surface defined by the leading edge points of cambered profiles.

The above formulae determine the hyperbolic character of the growth of ordinates (heights of rise) and moduli of negative slope angles of the water surface with increasing distances from the central plane in the transverse sections of the ascending flow generated by the tip vortices of the two forward planing surfaces downstream the gap between them. Thus, in order to optimize the hydrodynamic design at certain operational speed of the boat, to be conformal to the ascending flow, vertical longitudinal sections of the aft planing surface should be displaced in vertical direction in accordance with the ordinate of the slope (y) at the distance corresponding location of the aft planing surface from the forward planing surfaces and these sections should be turned down (nose-dive) to match the angle of elevation of the slope of the ascending flow at this location (β), while above displacements and turning of the sections of the aft planing surface should gradually grow from the center plane outward resulting in the configuration of half-planes of the aft surface being curved upwards and twisted down in a substantially hyperbolic manner.

The ordinate of the slope of the ascending flow at the location of each section of the aft planing surface relative to the base lines of the forward surfaces could be found from the following equation:

Y AFT = y ⁢ ( at ⁢ corresponding ⁢ “ x ” ⁢ and ⁢ “ d ” ) + d · tg ⁢ α FWD ,

• • where: α_FWD—angle of incidence of the base line of the forward planing surface relatively the undisturbed surface of water.

The angular requirement means that all vertical longitudinal sections of the aft planing surface are to be inclined (nose-dive) at some angles relatively the level of undisturbed water surface and the forward planing surfaces, by the angles of elevation of the slope of the ascending flow at their locations β (keeping at the same time the proper angle of incidence relatively the local surface of water determined by the ascending flow).

That results in a difference between the angular positions of the base lines of the forward and aft planing surfaces, so that the base lines of the aft planing surface are to be inclined relatively the base lines of the forward planing surfaces by the angles corresponding to the sum of the negative angles of the slope of the ascending flow relatively the level of undisturbed water surface (β) and the differences between the positive angles of incidence of the base lines of sections of the aft planing surface relatively the local surface of water corresponding to the ascending flow at the location of the aft planing surface, and the positive angles of incidence of the base lines of the forward planing surfaces relatively the level of undisturbed water surface.

The value of the angle between the base lines of the forward and aft planing surfaces (determining the optimum position of the aft planing surface conforming the ascending flow generated by the forward planing surfaces) should depend on a number of specific hydrodynamic characteristics, such as speed, dimensions, lift coefficient (that in its turn depends on the aspect ratio and the camber of arch of the profile) of the forward planing surfaces, the width of the gap and the position of the section within the gap.

Taking into account the dissipative wave nature of the ascending flow, the angles of inclination should also depend on the distance of the aft planing surface from the forward ones. However, in a certain range of sufficiently small distances, angular variations associated with the wave nature of this flow could be ignored.

The character of the vertical displacements and slope angles of the ascending flow downstream the gap determined by the above formulae, presupposes that for conformity of configuration of the aft planing surface with the shape of the flow formed by the forward vortex generators, both angles of deadrise and moduli (the absolute values) of negative angles of inclination of the sections of the aft planing surface must rise substantially hyperbolically spanwise from the center plane outwards.

At the same time, the infinite values of the required angles and displacements at the boundaries of the gap determined by the formulae should not be taken into account for the following reasons:

First, the hyperbolic growth of the “upwash” angles when approaching the vortex cord axis is limited by the diameter of core of the vortex. That is, the above formulae should be valid only within about 90% of the width of the gap.

On the other hand, vortices that have shed from the inner edges of the forward planing surfaces into the free flow can diverge laterally to a distance being different from the width of the gap by, e.g., about 10% or even more (depending on the ratio of the spans of the forward vortex generators to the width of the gap and the distance from the forward vortex generators downstream).

So, for sections of the aft planing surface by vertical longitudinal planes coinciding in projection onto the transverse plane with the inner vortex-generating edges of the forward planes, the angles and displacements will not go to infinity even without taking into account the dimensions of the vortex cores, while the above formulae should comply the real distance between the vortex cords different from the width of the gap.

Consequently, to meet the mentioned theoretically-requited distribution of the angles of deadrise and moduli of negative angles of inclination of the sections of the aft planing surface, in optimal configurations of practical designs of the aft planing surface, its half-planes should be curved upwards, and its camber-profiled sections should be gradually twisted down from the central plane outwards in a hyperbolic manner, but-reflecting the character of the real ascending flow-in the vertical planes corresponding the width of the gap between the two forward planing surfaces, the half-planes should not be vertical and sections should not be twisted to the vertical position, of course.

By utilizing the effect of ascending flow and efficient cambered planing surfaces, the hydrodynamic design of this invention can provide considerable efficiency improvements over the Prior Art designs.

As a conditional simplified example of evaluation illustrating the way of operation of the system of three planing surfaces according to this invention and the potential extent of drag reduction resulting in the significant increase in hydrodynamic efficiency, there can be considered a boat of the design based on the present invention with the aft planing surface supporting, e.g., 50% of the boat's weight, while the two forward vortex-generating planing surfaces support 25% of boat's weight each.

If the average angle of elevation of the ascending flow at the location of the aft planing surface is 3 degrees, the aft planing surface will use the ascending flow following this invention and as a result it will be inclined by additional 3 degrees nose-dive to match the flow, the directed generally upwards total vector of hydrodynamic force acting on the aft planing surface will be inclined by the 3 degrees forward too, that in projection to the horizontal plane will result in additional forward looking component (like a thrust force) of the order of 2.6% of the weight of the boat.

So, if the lift to drag ratio of planing surfaces (as single isolated planing surfaces) is 5 (corresponding, e.g., to flat not cambered planing surfaces) the hydrodynamic efficiency of the boat will increase by about 15%.

For the lift to drag ratio of planing surfaces equal to 10 the hydrodynamic efficiency of the boat could rise by about 35.5%.

In the case of highly efficient planing surfaces (cambered, properly profiled and adjusted, etc.) with lift to drag ratio as single isolated planing surfaces equal to 15, the same configuration under the above assumptions should result in hydrodynamic efficiency about 24.7 meaning rise by about 64.8% (which order of efficiency is completely unattainable for the known hydrodynamic designs of the Prior Art, of course).

This simplified example shows the principle of achieving the great maximum potential efficiency of the hydrodynamic design of the present invention, and that it can be realized primarily in the case of using cambered planing surfaces of high hydrodynamic efficiency and the aft planing surface being conformable to the flow generated by the forward planes, which would enable to utilize the full potential of the ascending flow and recover the maximum amount of the energy lost at the forward planing surfaces.

It should be noted that with high efficiency of the aft planing surface and large slope angles of the ascending flow, the resistance of the aft surface can be zero or even change sign, which would mean that the aft surface generates a pulling force/thrust.

For example, if the hydrodynamic efficiency of the aft planing surface is 15, then at the average angle of inclination of the ascending flow of about 3.8 degrees, the aft surface loses resistance. At larger angles it creates thrust, which, of course, does not mean that resistance of the entire hydrodynamic system of the three planing surfaces disappears because to form steeply sloping ascending flow the two forward surfaces should generate high intensity of vortices and high lift, and, so, should generate substantial drag. I.e., the proper distribution of lift should be the matter of optimization.

Although the above evaluation example is based on simplified assumptions, its principal conclusions are supported by the results of open water tests of a 2.15-meter/36.5 kg (7-foot/80-lb) concept-proving model equipped following this invention with a hydrodynamic system of three planing surfaces profiled corresponding the Virgil Johnson three-term camber curve.

On the one hand the two forward planing surfaces should be positioned close enough to each other in the transverse to the flow direction so that their tip vortices could generate maximum possible upward deviation of the flow, and the aft planing surface should be located close enough to the forward ones along the length of the boat in order to make full use of the effect of the ascending flow.

So, from this point of view, a narrower gap should result in more advantageous higher angles of ascending flow oncoming the aft planing surface.

However, the forward planing surfaces downstream of their trailing edges and outside the gap create unfavorable descending flows that can shade (in transverse plane view) the outer portions of the aft planing surface and prevent them from producing full-scale dynamic lift.

Thus, some too narrow gap could excessively decrease the active section-operational width, wetted area and actual aspect ratio of the aft planing surface-which reduces its dynamic lift and the positive effect relating to the utilization of the ascending flow, and diminishes the gain in efficiency the hydrodynamic system of the present invention and a boat based on this system could provide.

When closing the gap between the inner edges of the forward planing planes, the ascending flow will be completely suppressed and such connected hydrodynamic configuration of the forward surfaces will deflect all the flow down producing only negative effect on the aft surface and boat in general (similar to the step hull design).

Otherwise, excessively wide gap results in reduced angles of the ascending flow, a drop in the ascending flow effect on the aft surface and reduced efficiency of this hydrodynamic system and the boat as whole.

The optimal gap between the two forward planing surfaces should depend on specific hydrodynamic parameters, such as lift coefficients and dimensions of the forward planing surfaces and parameters of the aft planing surface.

As regards the longitudinal position of the aft planing surface which could maximize the use of the effect of ascending flow, there should be also noticed the following considerations:

Taking into account the wave nature of the ascending flow, at some distance downstream from the forward planing surfaces the angle of inclination of the ascending flow will decrease resulting in higher required trim angle of the aft planing surface and thereby reduction in the efficiency of this hydrodynamic system (which prevents it from being used to its full potential).

In these terms the aft planing surface should be located close enough to the forward ones, while the rational lengthwise position of the aft surface should depend on a number of factors and specific conditions including to a marked degree the Froude number.

Using the analogy with determining the parameters of the wave trough generated by a dynamic lift surface, which follows from the theory of hydrofoils, as a first approximation, the parameters of the ascending flow can be roughly assessed using formulae derived for the wave trough when applied to upside-down flow downstream the gap between the inner edges of the forward planing surfaces:

y = C y · [ 1 + ( Fr b 2 ⁢ ξ - 2 ) / 2 · λ ] · b · sin ⁡ ( d * / Fr b 2 ⁢ ξ ) ; β = ( C y / Fr b 2 ⁢ ξ ) · [ 1 + ( Fr b 2 ⁢ ξ - 2 ) / 2 · λ ] · cos ⁡ ( d * / Fr b 2 ⁢ ξ ) ,

• • where:
  • y—is the ordinate of the rise of the wave slope relatively the undisturbed water level;
  • β—is the angle of elevation of the wave slope;
  • b—chord of the forward planing surface;
  • C_y—lift coefficient of the forward planing surface;

Fr b = V / ( g · b ) 1 / 2 - Froude ⁢ Number ⁢ based ⁢ on ⁢ the ⁢ chord ⁢ of ⁢ the ⁢ forward ⁢ 
 planing ⁢ surface ;

• • g—acceleration of gravity;
  • λ—aspect ratio of the forward planing surface;
  • ξ=e^k; where: e—base of the natural logarithm; k=−0.73/λ^0.2
  • d*=d/b; where: d—distance from the forward planing surfaces along the flow.

In the original formulae developed for hydrofoils, the first term in square brackets (here it is equal 1) should reflect a decrease in wave disturbance of flow with increasing immersion of the hydrofoil and should have the following form:

• • e^ψ, where ψ=−h*/Fr_b^2ξ and h*=h/b, where h—immersion of hydrofoil that should be assumed equal zero for planing surfaces.

I.e., planing surfaces, ceteris paribus, maximize the ascending flow effect and surpass hydrofoils in its parameters, which make it reasonable to use this effect in planing hydrodynamic designs primarily.

The above formulae make it possible to evaluate the effect of the ascending flow and show that the maximum ascent of the flow could be found closer to the forward planing surfaces (in the direction along the flow) and, so, to achieve the ultimate use of the effect of ascending flow, the aft planing surface should be located practically closer to the forward ones.

Such conclusion contrasts the rules of conventional tandem hydrofoil systems and stepped hull designs of typical dimensions and Froude Numbers, where—to ensure the maximum efficiency—the aft hydrofoil plane or planing surface normally should be positioned as far aft of the forward one as possible.

Following the above analogy, there can be roughly estimated the order of a quarter of the wavelength of the ascending flow, which corresponds to the zeroing of the angle of the flow slope (at cos (d*/Fr_b^2ξ)=0) and which determines the limit of the positive effect this flow could create.

As for the above mentioned example, for the chord of forward planing surfaces (generating counter-rotating vortices) equal to b=0.5 m and a boat speed of V=20 m/see (72 km/h; 45 mph; 39 kt), the quarter wave length is about 9 m (30 feet).

That is, under above assumptions, the aft planing surface can be inclined to an additional negative angle and thereby reduce drag and increase the hydrodynamic efficiency of the boat if it is located no further than 9 meters (30 feet) downstream from the forward vortex generators.

On the other hand, it should be noted that the aft planing surface should not be located too close to the forward vortex-generating surfaces, which may cause a loss of dynamic stability of the system and the boat in the vertical longitudinal plane (along with a possibility that it can be affected by local disturbances of the unsettled ascending flow in the vicinity of the edges generating counter-rotating vortices).

As it was mentioned, the efficiency of this hydrodynamic design should depend on the angle of slope of the ascending flow generated by the forward planes.

Potentially, the flow-rising effect of the forward planes can be enhanced by means of a swept-back inverted-deadrise configuration of these surfaces, providing that the inner closer to the center plane gap-forming and vortex-generating edges of the two forward planing surfaces positioned higher and downstream of the outer more distant from the center plane edges.

Such configuration should channel the flow from peripheral areas towards the center plane and cause a higher ascent of the flow in the gap between the forward planing surfaces ensuring higher elevation angle. That in its turn will result in more inclined nose-dive position of the aft planing surface matching the elevation angle with corresponding reduction of hydrodynamic resistance and improvement in efficiency of the boat.

However, inward spraying generated by forward surfaces of inverted deadrise can nullify this effect and even lead to a drop in overall system efficiency.

As one of ways to increase lift coefficient of the forward planes and, so, to enhance the “upwash” in the gap of certain width, and hence the effect of using the ascending flow by the aft planing surface, is to provide the lift-generating surfaces of the forward planes with a concave shape in projection to the transverse plane.

The outer tips of both the forward vortex-generating cambered planing surfaces and the aft cambered planing surface can be provided with longitudinal end plates or deflectors, which increase hydrodynamic pressure and lift of the planing surfaces (while corresponding raise in the lift coefficient will result in a higher angle of slope of the ascending flow), reduce inductive drag (that is equivalent to increase in aspect ratio of the dynamic lift surfaces) and this way improve efficiency of this hydrodynamic system and the boat as a whole.

The hydrodynamic system of said three cambered planing surfaces arranged following provisions of this invention can be made as completely integrated into boat's bottom (can be laminated as a one-piece composite hull, e.g.). For this purpose the two forward vortex generating cambered planing surfaces can be integrated into bottoms of sponsons protruding down from the forward part of the boat bottom and spaced transversely relatively the center plane, and the aft cambered planing surface, located at the center plane of the boat further aft of the forward sponsons along the length of the boat, can be integrated into the aft part of boat bottom. Such an embodiment could significantly simplify the manufacture of a boat employing this hydrodynamic system.

However, in the course of practical development of a boat with the integrated hydrodynamic design according to the present invention, it could be found that optimum angles of deadrise of planing surfaces should be relatively small, which could determine low angles of deadrise of bottom surfaces mating with the planing surfaces, which, in turn, can deteriorate seaworthiness of the boat.

In this case at least some of the planing surfaces could be made in a form of flat-top panels or planes being separated from the bottom of the boat. This way the bottom surfaces of the boat could be provided with much higher angle of deadrise (much higher than the angle of deadrise of planing surfaces) and ensure much sharper entry that should considerably upgrade seaworthiness of the boat not sacrificing lift and hydrodynamic efficiency guaranteed by the optimum arrangement and configuration of separated planing surfaces corresponding provisions of this invention.

The separated panels and planes can be connected to the bottom by means of structural members comprising, e.g., struts with flanges, or flanges alone (in the case of direct attachment of the panel or plane to the keel of the boat's hull, e.g.).

Moreover, in some embodiments it may be found rational to distance at least some of the planing surfaces in the form of panels or planes somewhat further away from the bottom of the boat by means of hydrofoil-style struts that could further enhance seaworthiness of the boat.

In this case, taking into account that the struts should support planing surfaces skimming along the surface of water, said hydrofoil-style struts could be made much shorter than the struts of hydrofoils, which should result in less bulky design and much shallow draft in comparison with conventional submerged hydrofoils in the displacement mode, not to mention the negligible draft of planing surfaces in comparison with hydrofoils in the operational high-speed mode of motion.

This circumstance is added to the absence of cavitation and corresponding absence of speed limitation as the main advantage of this hydrodynamic planing system over hydrofoils.

Such technical solution allows the use of hydrodynamic systems according to this invention directly on the hulls of boats of any design, including conventional no-sponsons single-keel ones, in which case two forward planing surfaces are mounted on struts in the front part of the hull, and the aft planing surface is either suspended on struts below the aft part of boat's bottom, or not separated and integrated (laminated at once integrally with the boat's hull, e.g.) into the aft part of the boat bottom.

Either all the separated planing surfaces, or at least only the two forward separated planing surfaces (in the case of the integrated aft planing surface) can be made foldable or retractable and, thus, when folded, do not protrude below the keel line of the boat and beyond the dimensions of the boat's hull in general, which could substantially facilitate operation in shallow water in the displacement mode, lading of the boat and make the boat trailerable.

To further improve the ease of lading and trailing the boat, the planing surfaces in the folded position can be retracted into special recess niches on the bottom of the boat to make them flush with the bottom surfaces.

It would be reasonable to provide panels or planes of such separated design of planing surfaces with streamlined convex upper surfaces being similar to upper surfaces of hydrofoils.

That would give said separated panels or planes additional strength (keeping low drag) and additional lift during acceleration in transitional mode of motion (from floating displacement mode to purely planing mode till the upper surfaces of the planes should still be submerged), while during motion at operational speed in the purely planing mode said streamlined convex upper surfaces will be excluded from generation of lift. They will be positioned above the level of water, will not contact the water (washed only by air and without any risk of cavitation) and will not affect operation of the planing surfaces.

To facilitate the transition from displacement to planing mode, which involves the generation of dynamic lift only by the bottom part of the separated planes with exclusively positive hydrodynamic pressures, and to expand the range of speeds of pure planing on these separated planes, the front part of the bottom surfaces of the separated planes can be equipped with additional flat surfaces extending from the leading edges of the cambered profiled part of planes' bottoms forward to the leading edges of the entire separated planes.

Such flat surfaces can be aligned with the base lines of the cambered profiles of the separated planes.

The embodiment of the hydrodynamic system according to the present invention with separated planes could be perfectly suited to pontoon boats, which, by attaching (using struts and/or flanges) camber-profiled planing planes directly to bottoms of the logs, can increase their hydrodynamic efficiency to the greatest extent without any substantial alterations, i.e.:—significantly increase speed with the same engine power, or reduce the required power (and cost of the boat) without reducing speed, while providing in any case higher fuel efficiency (mpg), greater cruising range and lower specific emissions.

The abovementioned configuration makes it possible also to implement multi-mode hydrodynamic systems for boats (and, for example, motor yachts and high-speed ferries), which would provide minimum hydrodynamic resistance and maximum efficiency in a wide speed range:

If said separated cambered planing surfaces with hydrofoil-like convex upper part are mounted on bottoms of narrow streamlined floats supporting the boat above the water level in the displacement mode by Archimedean forces, such a vessel will have minimal hydrodynamic resistance and maximum efficiency in three consecutive modes of motion covering the full speed range of this vessel:

• • 1. The minimum resistance and maximum efficiency in the displacement mode of motion at low Froude numbers, provided by the narrow streamlined floats.
  • 2. The minimum resistance and maximum efficiency in the transitional “hydrofoil” mode, provided by high lift and efficiency of separated planes with convex upper surfaces operating as hydrofoils (while moderate transitional speeds do not cause the problem of cavitation).
  • 3. The principal operational high-speed and highly efficient mode of motion, when the boat is supported by the three planing surfaces only, while these three planing surfaces arranged as the hydrodynamic system utilizing the ascending flow effect and reproducing the provisions of this invention. In this case the boat will not have any speed limits caused by cavitation (since use of only planing surfaces that generate only positive hydrodynamic pressures) and will feature a negligible draft ensured by the planing surfaces just skimming along the water.

This way there could be achieved a smooth transition from low-speed modes of operation to high-speed ones and obtained gently sloping resistance vs. speed curve with low hump of a drag that in its turn should result in reduced power requirements, lower cost of the powerplant, longer range, etc.

In addition, supporting the hull of the boat above the water level in the displacement mode by said narrow streamlined floats with a small waterline area will make the boat less sensitive to wave impacts, which can significantly suppress pitching and rolling of the boat (which moreover should be vastly damped by submerged surfaces of separate planes) and substantially ameliorate the comfort of staying aboard.

These floats can be made directly attached to the hull of the boat and protruding downwards from the bottom of the hull, or suspended at some vertical distance from the hull and connected to the hull by means of such structural elements as struts.

In the latter case, the resulting gap between the floats suspended on the struts and the bottom of the boat hull prevents slamming, which is possible when encountering a large wave in the area where the inner surface of the float is attached to the bottom in the first option.

In this way, suspending the floats on struts allows to moderate the impact of waves, i.e., reduce structural loads and accelerations and thereby soften the ride in waves and increase the comfort of staying aboard during riding under high Sea States.

The penetration through large waves by the boat with floats suspended on struts can be further improved if the struts have elongated streamlined cross sections oriented along the inclined flow created as a result of the interaction of the wave and the bottom surfaces of the boat, determining location of the leading edges of sections closer to the center plane of boat than the trailing ones.

At the same time, providing such sections with a certain profile and angle of incidence allows such struts, when interacting with a wave, to generate a pulling hydrodynamic force (i.e., some additional thrust), which further facilitates riding under rough sea conditions.

Similar concept could be used in application to boats of catamaran configuration.

In this case each of the forward separated planing surfaces should be mounted under bottom of each corresponding forward part of catamaran hulls and the aft planing surface supposed to be positioned between the aft portions of the catamaran hulls. These planing surfaces should completely support the hulls during motion at operational speed and ensure low drag and high hydrodynamic efficiency, as well as shallow draft of such catamaran boat, while removing of the dynamic support function from the hulls and assigning this function to only separated planing surfaces makes it possible to provide the catamaran hulls with very sharp formations, which mitigates wave impacts and favorably affects the seaworthiness of such catamaran boat.

When implementing such a configuration, it is rational to directly abut and fasten the outer tips of the aft planing surface on the inner surfaces of the catamaran hulls. This completely stops the flow of water over the tip edges (up from the high pressure zone on the bottom working side of the aft planing surface), eliminates tip losses and increases the efficiency of both the aft planing surface and the boat as a whole.

In addition, the attachment of the outer tips of the aft planing surface to the hulls increases the strength of this design.

The intensity of vortices generated by the forward planing surfaces can be further enhanced and the efficiency of the hydrodynamic system of this invention can be further improved by means of arrangement of propulsion propellers downstream of the forward planing surfaces and upstream of the aft planing surface, on either side of the gap between the forward planes and in the paths of vortices shedding from the inner edges of the forward surfaces, so that the direction of rotation of the right-hand propeller is clockwise and the left one is counterclockwise when viewed from the front. This way propellers could additionally turn masses of water in the gap in the direction of rotation of vortices, assist them and contribute formation of a larger upward component of flow velocity resulting in steeper slope of the ascending flow, greater tilting (nose-dive) of the aft planing surface, lower drag and higher efficiency of the system and boat.

In corresponding embodiments the propellers being preferably coaxial to the chords of the shed tip vortices can be mounted on inner tips of forward planes and behind the trailing edges of forward planes (which is more suitable for semi-submerged propellers) or positioned separately between the forward and aft planing surfaces along the length of the boat in the wakes of tip vortices of forward planes, and supported by struts, brackets or propulsion drives.

As other possible applications, the hydrodynamic system of this invention can be used as a take-off and landing gear for seaplanes and wing-in-ground effect marine vehicles (WIGs).

The minimized hydrodynamic drag during the take-off of the flying vehicle (provided by said hydrodynamic system utilizing the ascending flow effect) guarantees the lowest possible power consumption, quick acceleration and the shortest take-off distance, without limiting take-off and landing speeds, which is a problem for take-off and landing gears using hydrofoils.

Accordingly, it is the object of this invention to provide a method and apparatus of various embodiments of a planing boat or a vehicle (including seaplanes and WIGs) using to support it in motion a hydrodynamic system comprising three cambered planing surfaces and employing the effect of generation of counter-rotating vortices by two transversely spaced forward planing surfaces and formation of ascending flow downstream the gap between these two forward surfaces in order to reduce hydrodynamic resistance of the aft planing surface and improve efficiency (lift to drag ratio) of this hydrodynamic system and the boat or vehicle in general by means of special spatial and angular relative arrangement of said three cambered planing surfaces and special configuration of the aft planing surface being conformant to the ascending flow.

SUMMARY OF THE INVENTION

Various embodiments are disclosed herein for a method and apparatus related to a boat or some other kind of vehicle operating in a planing mode of motion along water surface and supported at least partially by a hydrodynamic system of three cambered planing surfaces comprising: two forward cambered planing surfaces transversely set apart symmetrically the center plane and generating at their inner edges a couple of counter-rotating tip vortices resulting in formation of an ascending flow downstream the gap between said two forward planing surfaces, and one aft cambered planing surface located at the center plane further aft lengthwise of the boat or vehicle, at least partially within the limits of and affected by said ascending flow, while this hydrodynamic system of said three planing surface is configured spatially and angularly and the aft planing surface is shaped to be conformal to the ascending flow with the purpose to use the hydrodynamic effect of ascending flow in order to reduce hydrodynamic drag and improve efficiency of the boat or vehicle the following way:

Within the limits of the ascending flow vertical longitudinal sections of said aft cambered planing surface displaced higher than base lines of cambered profiles of the forward planing surfaces by the height corresponding the rise of the surface of the ascending flow above the base lines of the forward planing surfaces at the location of said section of the aft planing surface, and each base line of cambered profiles of said sections of the aft cambered planing surface is inclined nose-dive relatively the base lines of the forward planing surfaces by the angle being equal to the sum of the negative angle of the slope of the surface of the ascending flow and the difference between the positive angle of incidence of the base line of cambered profile of said section of the aft planing surface relatively the surface of the ascending flow and the positive angle of incidence of the base lines of the forward planing surfaces relatively the level of undisturbed water surface, which embodies in special spatial and angular relative arrangement of said three cambered planing surfaces, as well as a special shape of the aft planing surface featuring spanwise gradual increase of angles of deadrise and moduli of negative angles of inclination of sections of the aft cambered planing surface resulting in half-planes of the aft planing surface curved upwards and twisted downwards from the center plane outwards in a substantially hyperbolic manner.

The above specified configuration and position of the aft planing surface, conformal to the surface of the ascending flow and with sections inclined at the additional negative angle (nose-dive), leads to an inclination forward of the vector of the resulting lifting force of the aft planing surface, which results in a decrease in the rearward-directed drag-causing projection of this vector onto the horizontal plane (which is equivalent to the appearance of additional thrust) and, accordingly, a decrease in the resistance of the aft surface, this hydrodynamic planing system and the boat or vehicle as a whole.

Thus, the implementation of the design according to this invention can significantly increase the hydrodynamic efficiency (weight-to-drag ratio, for example) of the boat or vehicle to values exceeding those of the existing Prior Art, resulting in a decrease in power requirement for the same speed, or an increase in the speed at the same power, shorter and quicker take-off for seaplanes and WIGs and, in any case, improved fuel efficiency (mpg), longer range with the same amount of fuel, lower specific emissions, etc.

In some embodiments the outer ends of at least some of said cambered planing surfaces are provided with end plates or deflectors.

In some embodiments said two forward cambered planing surfaces made with variable angles of deadrise along their spans.

In some embodiments at least some of said cambered planing surfaces made swept.

In some embodiments said two forward planing surfaces represent bottom surfaces of two sponsons protruding downwards from the forward part of bottom of the boat or vehicle and transversely set apart both sides of the center plane of said boat or vehicle.

In some embodiments the camber of at least some of said planing surfaces is the Virgil Johnson three-term camber.

In some embodiments at least some of said cambered planing surfaces made in the form of panels or planes that are separated from the bottom of the boat or vehicle and connected to the bottom by means of structural members.

In some embodiments said structural members comprise struts and/or flanges.

In some embodiments said separated from the bottom panels or planes made with streamlined convex upper surfaces similar to the upper surfaces of hydrofoils.

In some embodiments said separated panels or planes are provided at their bottom part with flat portions connecting the leading edges of said panels or planes and the leading edges of the cambered profiled portions of said bottom part of said separated panels or planes.

In some embodiments said flat portions coincide with hydrodynamic base planes of said cambered profiled portions.

In some embodiments at least some of said separated from the bottom of the boat or vehicle cambered planing surfaces made foldable or retractable.

In some embodiments said two forward cambered planing surfaces are separated from the bottom of the boat or vehicle and the aft cambered planing surface is integrated into the aft part of bottom of said boat or vehicle.

In some embodiments said boat or vehicle is a pontoon boat provided with at least one hydrodynamic system according to this invention.

In some embodiments said separated panels or planes are mounted on bottoms of streamlined floats located under the hull of boat or vehicle.

In some embodiments said streamlined floats are suspended at some distance from the hull of the boat or vehicle and structurally connected to the hull by means of struts.

In some embodiments the suspended from the hull streamlined floats connected to the hull of the boat or vehicle by means of struts of elongated streamlined cross-sections, inclined relatively the center plane of the boat or vehicle so that the leading edges of said sections are located closer to the center plane than the trailing edges.

In some embodiments said boat or vehicle is a catamaran, wherein each of two forward separated panels or planes representing forward planing surfaces is mounted on the bottom of forward part of corresponding catamaran hull and one aft separated panel or plane representing said aft planing surface is located between catamaran hulls.

In some embodiments two propulsion propellers are located upstream of the aft planing surface and downstream of the forward planing surfaces, each on one side of the gap between the two forward planing surfaces in projection onto the transverse plane, providing that the direction of rotation of the right-hand propeller is clockwise and the left one is counterclockwise when viewed from the front.

In some embodiments said boat or vehicle is a seaplane or a wing-in-ground effect marine vehicle with take-off and landing gear employing the system of cambered planing surfaces according to this invention.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate exemplary embodiments, and together with the general description given above and the detailed description given below, serve to explain the features of the various embodiments.

FIG. 1 is a schematic diagram illustrating formation and utilization of ascending flow by the system of three dynamic lift surfaces.

FIG. 2 is a schematic diagram illustrating the side elevation view of a boat provided with the hydrodynamic system of three cambered planing surfaces comprising two forward vortex-generating planing surfaces separated from the bottom (left forward vortex-generating planing surface and its strut are conditionally removed) and one aft planing surface being integrated into the aft part of boat's bottom according to some embodiments, which diagram clarifies the spatial and angular arrangement of the three cambered planing surfaces following this invention.

FIG. 3 is a schematic diagram illustrating the plan bottom view of a boat provided with the hydrodynamic system of cambered planing surfaces according to some embodiments.

FIG. 4 is a schematic diagram illustrating the front elevation view of a boat provided with the hydrodynamic system of cambered planing surfaces comprising two forward vortex-generating planing surfaces separated from the bottom and one aft planing surface being integrated into the aft part of boat's bottom according to some embodiments.

FIG. 5 is a schematic diagram that illustrates the perspective forward bottom view of a boat provided with the hydrodynamic system of three cambered planing surfaces, wherein two forward vortex-generating planing surfaces made separated from the bottom and one aft planing surface is integrated into the aft part of boat's bottom according to some embodiments.

FIG. 6 is a schematic diagram illustrating the front elevation view of a boat provided with the hydrodynamic system of three cambered planing surfaces being separated from the bottom of the boat according to some embodiments.

FIG. 7 is a schematic diagram that illustrates the perspective forward bottom view of a boat provided with the hydrodynamic system of three cambered planing surfaces, wherein all three planing surfaces made separated from the bottom of the boat according to some embodiments.

FIG. 8 is a schematic diagram that illustrates an along the flow sectional view of a separated planing surface provided with hydrofoil-like concave upper surface according to some embodiments.

FIG. 9 is a schematic diagram that illustrates the perspective aft bottom view of a boat provided with the hydrodynamic system of three cambered planing surfaces, wherein two forward vortex-generating planing surfaces made integrated into bottom surfaces of sponsons and the aft planing surface is integrated into the aft part of boat's bottom according to some embodiments.

FIG. 10 is a schematic diagram illustrating the front elevation view of a boat provided with the hydrodynamic system of separated cambered planing surfaces being mounted on bottoms of three streamlined floats according to some embodiments.

FIG. 11 is a schematic diagram that illustrates the rear perspective view of a bottom of boat provided with the hydrodynamic system of separated cambered planing surfaces being mounted on bottoms of three streamlined floats comprising two forward floats separated from the hull of the boat and connected to the hull by means of streamlined profile struts installed obliquely relative to the central plane according to some embodiments.

FIG. 12 is a schematic diagram illustrating the front elevation view of a boat of catamaran configuration provided with the hydrodynamic system of separated cambered planing surfaces according to some embodiments.

FIG. 13 is a schematic diagram illustrating the front elevation view of a boat of catamaran configuration provided with the hydrodynamic system of separated cambered planing surfaces and featuring semi-submerged counter-rotating propellers arranged on the inner tips of forward vortex-generating planing surfaces according to some embodiments.

FIG. 14 is a schematic diagram illustrating the bottom plan view of a boat of catamaran configuration provided with the hydrodynamic system of separated cambered planing surfaces and featuring semi-submerged counter-rotating propellers mounted on the inner tips of forward vortex-generating planing surfaces according to some embodiments.

FIG. 15 is a schematic diagram illustrating the bottom plan view of a boat of catamaran configuration provided with the hydrodynamic system of cambered planing surfaces and featuring counter-rotating propulsion propellers arranged as separate units and positioned between the forward and aft lifting surfaces along the length of the boat in the wakes of inner tip vortices of forward vortex-generating planes, and supported by struts, brackets or propulsion drives according to some embodiments.

FIG. 16 is a schematic diagram illustrating the front elevation view of a single-keel boat provided with the hydrodynamic system of cambered planing surfaces with separated from the bottom foldable forward vortex-generating planing surfaces and the aft planing surface integrated into the aft part of the bottom of the boat according to some embodiments, wherein semi-submerged counter-rotating propulsion propellers arranged along the length of the boat downstream the forward planing surfaces and upstream the aft planing surface in the wakes of tip vortices of forward vortex-generating planing surfaces, and supported by foldable propulsion drives mounted on the bottom of the boat, while both the forward planing surfaces and the propulsion drives are shown in the operational unfolded position.

FIG. 17 is a schematic diagram illustrating the front elevation view of a single-keel boat basically corresponding to the embodiment of the FIG. 16, wherein both separated from the bottom forward planing surfaces and propulsion drives with propellers are shown in the retracted position.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference will be used throughout the drawings to refer to the same or like parts. References made to particular examples and implementations are for illustrative purposes, and are not intended to limit the scope of the claims.

FIG. 1 depicts a schematic diagram illustrating formation and use of ascending flow by the system of three planing surfaces. The diagram shows the perspective view of the system of planing surfaces comprising two forward planing surfaces “FPS” set apart transversely to the direction of flow “FL” and forming a gap between their inner facing each other edges “IE”, and the aft planing surface “APS” with its center plane section “CPS” arranged downstream of said gap.

The forward planing surfaces “FPS” being positioned in the flow “FL” generate dynamic lift by means of a positive pressure on their bottom surfaces. That coerces the ambient water to flow from the high pressure zones on bottoms of the forward planing surfaces “FPS” to the lower pressure zones over said inner edges “IE” up that results in rotational movement of masses of water around longitudinal axis and formation of a cord of tip vortices “VX” shedding from the inner edges “IE” and carried away by the flow downstream.

Correspondingly, for the above configuration of two transversely spaced forward planing surfaces “FPS”, the direction of rotation of the tip vortices “VX” generated by the inner edge “IE” of the right-hand forward dynamic lift surface is clockwise, and the left one is counterclockwise, when viewed from the front.

This counter-rotational pattern of motion of the water masses, initiated by vortices “VX” at opposite ends of the gap between the two forward planing surfaces “FPS”, causes the masses of water in the gap to move upward, while this disturbance of motion of water propagates downstream the flow.

Thus, these counter-rotating vortices generate a velocity field in the gap between said forward planing surfaces with a velocity component “V_VA” directed upwards, which in combination with the velocity of ambient flow “V₀” results in an ascending flow with cumulative velocity “V_ΣA” downstream the forward planing surfaces “FPS”, while the vector “V_ΣA” is inclined at some negative angle “β” to the to the direction of flow “FL” (i.e., turned counterclockwise if viewed from the right side of the picture and the port side of this hydrodynamic system).

So, the aft planing surface “APS” arranged amid this gap in the projection to the transverse to the flow plane and somewhat aft of the mentioned parallel-moving forward planing surfaces “FPS” could be inclined nose-dive and this way positioned more favorably in terms of reduction of the resistance of form, keeping at the same time some proper angle of incidence relatively the local oncoming ascending flow in order to generate required lift. That ultimately leads to a decrease in resistance and improvement in efficiency (lift to drag ratio) of such three-surface dynamic lift system.

The essence of this process is as follows:

In the case of placement of the aft dynamic lift surface “APS” within the range of ascending flow inclined at some negative angle “β” to the to the direction of flow “FL” and corresponding nose-dive inclination of the surface “APS” by the angle “β” (keeping at the same time the required angle of incidence relatively the local flow corresponding to the ascending flow), the directed upwards vector of the dynamic lift force “L” of the aft surface will be tilted forward in the direction of movement of the system (i.e., turned counterclockwise if viewed from the port side of this hydrodynamic system) by the angle corresponding to the angle of slope of the ascending flow “β”, and the projection of said tilted upward lift vector “L” onto the horizontal plane will produce an additional forward-looking component “T” (being similar to some additional thrust) that reduces fluid drag and increases the fluid dynamic efficiency of the system.

To illustrate formation of the forward-looking horizontal component, the vector “L” in FIG. 1 conditionally shown inclined forward, while for real practical designs vector “L” can be tilted back creating a rearward projection onto the horizontal plane, which determines the resistance of this aft planing surface.

In this case, turning the aft surface “APS” to the nose-dive position corresponding the ascending flow will result in turning the tilted back vector “L” counterclockwise forward and its arrangement closer to the vertical with resulting reduction of the horizontal projection and, correspondingly, reduction of the resistance. Consequently, the difference in horizontal projections for inclined and non-inclined positions will determine the vector “T”.

This way the aft planing surface “APS” actually recovers some part of the energy spent by the forward planing surfaces “FPS” to disturb the incoming ambient flow and to deviate the masses of ambient water upwards relatively the undisturbed water surface in the form of generation of the ascending flow.

At the same time, under certain conditions corresponding, for example, to large angles of inclination of the ascending flow “B” and high hydrodynamic efficiency of the aft surface “APS” (determining low resistance stipulated by slightly tilted back close to vertical vector “L” with a small rearward horizontal projection in the non-inclined position), the vector “L” for the inclined position can indeed be tilted forward from the vertical and create only the pulling force “T”, as shown in FIG. 1.

This entire effect can be realized only if the configuration of the aft planing surface “APS” matches the shape of surface of the ascending flow, so that in each vertical longitudinal plane within the range of interaction, sections of the aft planing surface “APS” would be located in height in accordance with the height of the rise of the ascending flow above the undisturbed level of the water surface and, accordingly, above the forward planing surfaces “FPS”, and would be rotated an additional nose-dive angle, while providing the angle of incidence relative to the ascending flow required to generate the necessary lift “L”, which should determine the optimal relative arrangement of the forward “FPS” and aft “APS” planing surfaces in this hydrodynamic system.

Taking into account the shape of the cross sections and the spanwise distribution of the angles of inclination “B” of the surface of the ascending flow generated by two parallel counter-rotating vortex cords “VX” (created by the two forward planing surfaces “FPS”), the above requirements dictate the configuration of the aft planing surface “APS” (being necessary for the implementation of the positive effect of the ascending flow) with gradually increasing along the span angles of deadrise and modules of the additional negative angles of inclination of sections, which is embodied in the half-planes of the aft planing surface curved upward and twisted down in a substantially hyperbolic manner.

The indicated spatial and angular relative arrangement of the forward “FPS” and aft “APS” planing surfaces, as well as the configuration of the aft surface “APS” with its half-planes having substantially hyperbolic bending and twist, provide a significant reduction in drag and an increase in the hydrodynamic efficiency of both this hydrodynamic system and the boat or vehicle using such system in accordance with the provisions of this invention.

FIG. 2 depicts a schematic diagram illustrating the side elevation view of a boat according to some embodiments, wherein two separated forward vortex-generating planing surfaces arranged symmetrically on the left and right sides of boat's bottom and supported by struts, while the aft planing surface is integrated into the aft part of boat's bottom.

In this diagram the port-side forward vortex-generating planing surface with its strut is conditionally removed to clarify the positions of the forward and aft planing surfaces relatively each other, the undisturbed ambient water surface and the ascending flow generated by the forward vortex-generating surfaces.

In the diagram the boat 201 moves at operational speed corresponding Froude numbers of about or in excess of 3, along the undisturbed water surface “W” in the direction “F”. In this embodiment the boat 201 is provided in its forward part with two struts 202 supporting separated from the bottom of boat 201 forward cambered planing surfaces 203 (only starboard side surface and strut are visible in this elevation) represented by their profiled wetted areas (being hatched in this diagram) with their base planes 204 shown here coinciding with the hydrodynamic base planes of cambered profiles of their lowermost sections 205 and positive (i.e., measured clockwise in this diagram) angle of incidence 206 determined by the position of their base planes relatively the undisturbed water surface “W”, which forward cambered planing surfaces 203 generate dynamic lift and contribute the dynamic support of the boat 201 in motion.

The port and starboard cambered planing surfaces 203 set apart both sides of the boat's center plane and generate at their inner edges (facing each other and the center plane) two counter-rotating tip vortices, which create the ascending flow conditionally shown by the center plane surface line 207 in the gap between said inner edges and further aft downstream the flow.

The boat 201 is provided also with the third aft cambered planing surface 208 located in the center plane of the boat 201 at some distance aft from the forward planing surfaces 203, supposed to be integrated into the aft part of bottom and represented by its profiled wetted area being hatched in this diagram. This aft planing surface 208 features its leading edge 209, the exemplified base plane 210 shown here coinciding with the hydrodynamic base plane of cambered profile of its center plane keel section 211 and the positive angle of incidence 212 of this section 211 relatively the local surface of water corresponding to the ascending flow 207.

The aft planing surface 208 supposed to keep the required vertical position in order to provide proper position of the boat 201 and accordingly the required angle of incidence 206 of the forward surfaces 203, and to keep the required angle of incidence 212 relatively the local surface of water in order to generate the required lift, and in these terms the vertical and angular position of the aft planing surface 208 (represented in this diagram by the keel point of the leading edge 209 and the base plane 210) should correspond the local ascending flow 207.

To match the parameters of local flow 207 the aft cambered planing surface 208 in its center plane section positioned higher than the base planes 204 of the forward surfaces 203 by the height 213 of the ascending flow 207 above the base planes 204 at the location of the leading edge 209 of the center plane keel sections 211 and turned counter-clockwise (nose-dive) by the angle 214 of the ascending flow 207 at the location of the leading edge 209 of the center plane keel sections 211 relatively the level of undisturbed water surface “W”.

Thus, as a result, the base plane 210 of the aft cambered planing surface 208 positioned at the angle 215 relatively the base planes 204 of the forward surfaces 203, which negative angle 215 represents the combination of the angles 206, 214 and 212. That is: the negative angle 214 plus the difference between the positive angles 212 and 206 (angle 212 minus angle 206).

In a similar way, the vertical and angular positions of other longitudinal vertical sections of the aft planing surface 208 are determined in accordance with the rise and inclination of the ascending flow in these sections, which results in a certain spatial and angular arrangement of the sections and their base planes relative to the sections and base planes of the forward vortex generators 203 (as well as, accordingly, the aft planing surface as a whole relatively the surfaces 203) and, taking into account the shape of the surface of the ascending flow formed by the velocity field generated by the two counter-rotating parallel vortex cords, determines the configuration of the aft surface with gradually increasing deadrise angles and modules of negative angles of inclination of sections from the central plane outward in such a way that the half-planes of the aft surface are curved up and twisted down in a substantially hyperbolic manner.

Consequently, for the same center plane section 211 of the aft cambered planing surface 208 if skimming along the undisturbed water surface “W”, the vector of the dynamic lift force would be directed upward and somewhat backward (creating rearward directed horizontal projection responsible for the hydrodynamic drag).

However, as a part of the hydrodynamic system under consideration, to be conformant to the ascending flow 207 the section 211 and, so, the vector of the dynamic lift force will be turned counterclockwise (i.e., forward in the direction of movement of the boat) by the angle corresponding to the angle of elevation 214 of the ascending flow 207 at the location of the leading edge 209, which new position of the lift vector will affect, reduce and may be even change the sign of its projection onto the horizontal plane.

Similarly, the tilting of the dynamic lift vectors will occur in other sections of the aft planing surface.

Accordingly, the resulting lift vector of the aft planing surface 208 in general will tilt forward as well that will lead to reduction of the directed backwards (i.e., generating drag) projection of said lift vector onto the horizontal plane, while ultimately such tilting could even change the sign of this horizontal projection in the case of high hydrodynamic efficiency of the aft surface and high angles of slope of the ascending flow.

This reduction of said directed backwards horizontal projection (and, moreover, change of its sign) occurring on the aft planing surface could be considered as the appearance of an additional directed forward horizontal force (being similar to some additional thrust, although the resistance of the entire hydrodynamic system of the three planing surfaces, of course, could reduce but would remain effective) that will reduce drag and increase the hydrodynamic efficiency of the boat 201.

That is, in this way said aft planing surface 208 will actually recover a part of the energy spent by the forward planing surfaces 203 to disturb the incoming flow and to lift the water in the gap between the forward planing surfaces 203 above the level of undisturbed water surface “W” in the form of generation of the ascending flow 207.

FIG. 3 depicts a schematic diagram illustrating the bottom plan view of the boat according to some embodiments, where the boat 201 is provided with two swept back forward planing surfaces 203 represented by their profiled wetted areas being hatched in this diagram, which two forward planing surfaces 203 set apart both sides of the boat's center plane and form the gap with the width 301, and one aft planing surface 208 represented by its profiled wetted area being hatched in this diagram, while said aft planing surface 208 with the width 302 located at the center plane of the boat 201. Sections of the aft planing surface 208 by vertical longitudinal planes are positioned at the distance 304 aft from the forward planing surfaces measured along the length of the boat 201 up to the leading edges of sections of the aft planing surface 208 and represented in this diagram by section 305. This diagram assumes that the forward planing surfaces 203 are separated from the bottom of the boat 201 and the aft planing surface 208 is integrated into the aft part of the bottom of the boat 201, while the span of the aft surface 208 in the transverse direction is limited by deflectors 306.

The inner (facing the center plane of the boat 201 and each other) edges 303 of the forward planing surfaces 203 generate tip vortices of opposite rotation (relatively their axes arranged along the flow) eventually shedding from the edges 303 and surfaces 203, carried downstream by the flow and forming the core lines while turning the masses of water (around the vortices' core lines) in the gap channel between forward planing surfaces 203 up and producing a velocity field in the gap with a velocity component directed upwards, which creates an ascending flow downstream the planing surfaces 203, rising above the undisturbed water level and inclined to this level at some negative angle.

To ensure hydrodynamically favorable relative spatial and angular positions of the surfaces 203 and 208, as well as the configuration of the aft cambered planing surface 208 matching the ascending flow in order to use the ascending flow effect, each section by vertical longitudinal planes of the aft cambered planing surface 208 is arranged higher (lower in this upside-down position) than the base lines of the forward planing surfaces 203 by the height of the surface of ascending flow above the base lines of the forward planing surfaces 203 at the location of the leading edges of sections of the aft cambered planing surface 208, and the base lines of said sections of the aft surface 208 turned nose-dive (nose-up in this upside-down position) relatively the base lines of the forward planing surfaces by the angle corresponding the negative angle of slope of the surface of ascending flow at the location of the leading edges of sections of the aft cambered planing surface 208.

So that the angle between the base lines of each section of the aft 208 and forward 203 planing surfaces constitutes the sum of the negative angle of the slope of the surface of the ascending flow relatively the level of the undisturbed water surface at the location of this section of the aft planing surface 208 and the difference between the angle of incidence of the base line of the section of the aft planing surface 208 relatively the local surface of water corresponding to the surface of the ascending flow at the location of said section of the aft planing surface 208 and the angle of incidence of the base lines of the forward planing surfaces 203 relatively the level of the undisturbed water surface. Consequently, taking into consideration the shape of the surface of the ascending flow generated by two parallel along the flow counter-rotating vortex cords, in order to meet the above requirements for the hydrodynamically efficient configuration of the aft planing surface 208 conforming the ascending flow, angles of deadrise and moduli of negative (nose-dive) angles of inclination of base lines of sections of the aft planing surface 208 relatively the base lines of the forward planing surfaces should gradually increase along the span of the aft planing surface from the center plane of the system outwards resulting in half-planes of said aft planing surface being curved upwards and twisted downwards in a substantially hyperbolic manner.

In this case, the directed upward vector of the dynamic lift force of the aft cambered planing surface 208 will be turned forward in the direction of movement of the boat and the associated with drag projection of said lift vector onto the horizontal plane will reduce or even will change sign (will change direction to the opposite), which resulting reduced or even opposite-directed drag-determining projection will be equivalent to the appearance of an additional forward-looking component of the horizontal force, similar to some additional thrust that will reduce drag and increase the hydrodynamic efficiency of the boat 201.

That is, in this way said aft planing surface 208 will actually recover a part of the energy spent by the forward planing surfaces 203 to disturb the incoming water flow and to raise the water in the gap between the forward planing surfaces 203 above the level of undisturbed water surface in the form of generation of the ascending flow.

In this embodiment span-limiting deflectors 306 of the aft planing surface 208 increase hydrodynamic pressure and lift of this planing surface, reduce inductive drag (which is equivalent to increase in aspect ratio of these dynamic lift surfaces) and this way further improve efficiency of this hydrodynamic system and the boat 201 as a whole.

In said hydrodynamic system the ratio of the width 301 to the width 302 can be optimized for specific parameters of motion and design of the boat 201 taking into consideration the diameter of the cores of the vortices generated by the planing surfaces 203 at the edges 303 and the transverse deviation of the vortices' core lines downstream the forward surfaces 203.

As for size 304, taking into account the wave nature of the ascending flow, in order to maximize the use of the effect of ascending flow, the aft planing surface 208 should be preferably located not far aft from the forward planing surfaces 203, within the range of high angles of slope of the ascending flow, and anyway not further than the length of the quarter of the wave of the ascending flow, but not too close to the surfaces 203, keeping in mind, first of all, the dynamic stability of the boat 201 in the vertical longitudinal plane.

FIG. 4 depicts a schematic diagram illustrating the front elevation view of a boat according to some embodiments and basically corresponding to the embodiment of the FIG. 3, where a boat 201 provided with two forward vortex-generating cambered planing surfaces 203 with their inner edges 303 and outer side deflectors 401, which planing surfaces are separated from the bottom of the boat 201, connected structurally with the bottom by means of struts 202 and are cantilevered at the lower ends of the struts 202, and the aft cambered planing surface 208 being integrated into the aft part of the bottom of the boat 201 and limited spanwise by deflectors 306.

The forward planing surfaces 203 on facing each other inner edges 303 generate vortices “VX” of opposite rotation with the right vortex rotating clockwise and the left one rotating counterclockwise.

Said vortices “VX” produce a flow velocity field in the gap between and downstream the planing surfaces 203 with a velocity component directed upwards, which creates an ascending flow downstream these planing surfaces 203, rising above the undisturbed water level and inclined at some negative angle to this level.

To ensure hydrodynamically favorable relative spatial and angular positions of the surfaces 203 and 208, as well as the configuration of the aft cambered planing surface 208 matching the ascending flow in order to use the ascending flow effect, each section by vertical longitudinal planes of the aft cambered planing surface 208 is arranged higher than the base lines of the forward planing surfaces 203 by the height of the surface of ascending flow above the base lines of the forward planing surfaces 203 at the location of the leading edges of sections of the aft cambered planing surface 208, and the base lines of said sections of the aft surface 208 turned nose-dive relatively the base lines of the forward planing surfaces by the angle corresponding the negative angle of slope of the surface of ascending flow at the location of the leading edges of sections of the aft cambered planing surface 208.

So that the angle between the base lines of each section of the aft 208 and forward 203 planing surfaces constitutes the sum of the negative angle of the slope of the surface of the ascending flow relatively the level of the undisturbed water surface at the location of this section of the aft planing surface 208 and the difference between the angle of incidence of the base line of the section of the aft planing surface 208 relatively the local surface of water corresponding to the surface of the ascending flow at the location of said section of the aft planing surface 208 and the angle of incidence of the base lines of the forward planing surfaces 203 relatively the level of the undisturbed water surface.

Consequently, taking into consideration the shape of the surface of the ascending flow generated by two parallel along the flow counter-rotating vortex cords, in order to meet the above requirements for the hydrodynamically efficient configuration of the aft planing surface 208 conforming the ascending flow, the angles of deadrise and moduli of negative (nose-dive) angles of inclination of base lines of sections of the aft planing surface 208 relatively the base lines of the forward planing surfaces should gradually increase along the span of the aft planing surface from the center plane of the system outwards resulting in half-planes of said aft planing surface being curved upwards and twisted downwards in a substantially hyperbolic manner.

In this case, the directed upward vector of the dynamic lift force of the aft cambered planing surface 208 will be turned forward in the direction of movement of the boat and the associated with drag projection of said lift vector onto the horizontal plane will reduce or even will change sign (will change direction to the opposite), which resulting reduced or even opposite-directed drag-determining projection will be equivalent to the appearance of an additional forward-looking component of the horizontal force, similar to some additional thrust that will reduce drag and increase the hydrodynamic efficiency of the boat 201.

That is, in this way said aft planing surface 208 will actually recover a part of the energy spent by the forward planing surfaces 203 to disturb the incoming water flow and to raise the water in the gap between the forward planing surfaces 203 above the level of undisturbed water surface in the form of generation of the ascending flow.

In this embodiment span-limiting deflectors 306 of the aft planing surface 208 and the deflectors 401 at the outer ends of the forward vortices-generating planing surfaces 203 increase hydrodynamic pressure and lift of these planing surfaces (while corresponding raise in the lift coefficient of the forward planing surfaces 203 will result in a higher angle of slope of the ascending flow), reduce inductive drag (which is equivalent to increase in aspect ratio of these dynamic lift surfaces) and this way further improve efficiency of this hydrodynamic system and the boat 201 as a whole.

Through separating the forward planing surfaces 203 from the bottom of the boat 201 the described embodiment combines the hydrodynamic design of the present invention with a conventional single-keel configuration of the bow part of boat hull, while the bottom surfaces of the boat at its bow part can be made with much higher angle of deadrise indicated by the dotted line 402 and ensure much sharper entry that should considerably upgrade seaworthiness of the boat, not sacrificing lift and hydrodynamic efficiency (provided by the hydrodynamic system employing the ascending flow effect and configured according to provisions of this invention).

The aft planing surface 208 in this embodiment does not require manufacturing as a separate unit and in the case of use of composite structural material (fiber reinforced plastics, e.g.) can be laminated at once altogether with the hull of the boat 201.

FIG. 5 is a schematic diagram that illustrates the perspective front bottom view of a boat according to some embodiments and basically corresponding to the embodiments of the FIG. 3 and FIG. 4, where the boat is provided with the hydrodynamic system comprising two forward vortex-generating cambered planing surfaces being separated from the bottom of the boat and one aft planing surface being integrated into boat's bottom.

In this embodiment the boat 201 is provided with two forward vortex-generating cambered planing surfaces 203 connected structurally with the bottom by means of struts 202 and extend inward from the lower ends of the struts 202.

The port and starboard cambered planing surfaces 203 set apart both sides of the boat's center plane and generate at their inner edges 303 two counter-rotating tip vortices, which create the ascending flow in the gap between said inner edges and further aft downstream the flow.

The boat 201 is provided also with the third aft cambered planing surface 208 arranged in the center plane of the boat 201 and integrated into boat's bottom at some distance aft from the forward planing surfaces 203.

To ensure hydrodynamically favorable relative spatial and angular positions of the surfaces 203 and 208, as well as the configuration of the aft cambered planing surface 208 matching the ascending flow in order to use the ascending flow effect, each section by vertical longitudinal planes of the aft cambered planing surface 208 is arranged higher (lower in this upside-down position) than the base lines of the forward planing surfaces 203 by the height of the surface of ascending flow above the base lines of the forward planing surfaces 203 at the location of the leading edges 209 of sections of the aft cambered planing surface 208, and the base lines of said sections of the aft surface 208 turned nose-dive (nose-up in this upside-down position) relatively the base lines of the forward planing surfaces by the angle corresponding the negative angle of slope of the surface of ascending flow at the location of the leading edges of sections of the aft cambered planing surface 208.

So that the angle between the base lines of the sections of the aft 208 and forward 203 planing surfaces constitutes the sum of the negative angle of the slope of the surface of the ascending flow relatively the level of the undisturbed water surface at the location of each section of the aft planing surface 208 and the difference between the angle of incidence of the base line of the section of the aft planing surface 208 relatively the local surface of water corresponding to the surface of the ascending flow at the location of said section of the aft planing surface 208 and the angle of incidence of the base lines of the forward planing surfaces 203 relatively the level of the undisturbed water surface.

Consequently, taking into consideration the shape of the surface of the ascending flow generated by two parallel along the flow counter-rotating vortex cords, in order to meet the above requirements for the hydrodynamically efficient configuration of the aft planing surface 208 conforming the ascending flow, the angles of deadrise and moduli of negative (nose-dive) angles of inclination of base lines of sections of the aft planing surface 208 relatively the base lines of the forward planing surfaces should gradually increase along the span of the aft planing surface from the center plane of the system outwards resulting in half-planes of said aft planing surface being curved upwards and twisted downwards in a substantially hyperbolic manner.

In this case, the directed upward vector of the dynamic lift force of the aft cambered planing surface 208 will be turned forward in the direction of movement of the boat and the associated with drag projection of said lift vector onto the horizontal plane will reduce or even will change sign (will change direction to the opposite), which resulting reduced or even opposite-directed drag-determining projection will be equivalent to the appearance of an additional forward-looking component of the horizontal force, similar to some additional thrust that will reduce drag and increase the hydrodynamic efficiency of the boat 201.

That is, in this way said aft planing surface 208 will actually recover a part of the energy spent by the forward planing surfaces 203 to disturb the incoming water flow and to raise the water in the gap between the forward planing surfaces 203 above the level of undisturbed water surface in the form of generation of the ascending flow.

In this embodiment span-limiting deflectors 306 of the aft planing surface 208 and the deflectors 401 at the outer sections of the forward vortices-generating planing surfaces 203 increase hydrodynamic pressure and lift of these planing surfaces (while corresponding raise in the lift coefficient of the forward planing surfaces 203 will result in a higher angle of slope of the ascending flow), reduce inductive drag (which is equivalent to increase in aspect ratio of these dynamic lift surfaces) and this way further improve efficiency of this hydrodynamic system and the boat 201 as a whole.

The aft planing surface 208 in this embodiment does not require manufacturing as a separate unit and in the case of use of composite structural material (fiber reinforced plastics, e.g.) can be laminated at once altogether with the hull of the boat 201.

FIG. 6 depicts a schematic diagram illustrating the front elevation view of a boat according to some embodiments, where the boat 201 provided with three cambered planing surfaces being separated from the bottom of the boat 201 and comprising: two forward vortex-generating cambered planing surfaces 203 with their inner edges 303 and outer side deflectors 401, which planing surfaces are connected structurally with the bottom by means of struts 202 and extend inward from the lower ends of the struts 202, and the aft cambered planing surface 208 representing a separated from the bottom unit. The aft surface 208 is provided with end deflectors 306 and structurally connected to the bottom of the boat 201 by means of the keel strut or flange 601 and side struts 602, while designation 1-1 indicates the along the flow section of the forward planing surfaces 203.

Like in previously mentioned embodiments, the inner edges 303 of the forward planing surfaces 203 generate vortices “VX” of opposite rotation producing a velocity field in the gap between planing surfaces and further aft with a velocity component directed upwards, which velocity field creates an ascending flow downstream these forward planing surfaces, rising above the undisturbed water level and inclined at some negative angle of elevation to this level, while vertical longitudinal sections of the separated aft planing surface 208 made conformal to the shape of the surface of the ascending flow and have the angular position taking into account the negative angle of inclination of the surface of the upward flow, which determines the spatial position of sections of the aft surface 208 above the base lines of the forward surfaces 203, the inclination of the base lines of the sections of the aft surface 208 nose-dive relative to the base lines of the forward surfaces 203 at the angles of inclination of the ascending flow, and the configuration of the aft surface 208 with gradually increasing from the central plane outward deadrise angles and moduli of negative angles of inclination of sections resulting in its half-planes curved upward and twisted downward in a substantially hyperbolic manner.

Through utilization of the above features of the ascending flow, the resulting configuration as well as spatial and angular position of the aft planing surface 208 relatively the forward planing surfaces 203 reduces the hydrodynamic drag of this system of the three planing surfaces and increases the efficiency of the boat 201.

In this embodiment span-limiting deflectors 306 of the aft planing surface 208 and the deflectors 401 at the outer sections of the forward vortices-generating planing surfaces 203 increase hydrodynamic pressure and lift of these planing surfaces (while corresponding raise in the lift coefficient of the forward planing surfaces 203 will result in a higher angle of slope of the ascending flow), reduce inductive drag (which is equivalent to increase in aspect ratio of these dynamic lift surfaces) and this way further improve efficiency of this hydrodynamic system and the boat 201 as a whole.

By means of separation of the hydrodynamic system featuring the two forward cambered planing surfaces 203 and one aft cambered planing surface 208 from the bottom of the boat 201, in this embodiment the bottom surfaces of the boat 201 are independent of the geometric shapes that are optimal for planing surfaces 203 and 208 and provided with much higher angle of deadrise (much higher than the angle of deadrise of planing surfaces) and this way ensure much sharper entry that should considerably upgrade seaworthiness of the boat 201 not sacrificing lift and hydrodynamic efficiency ensured by the spatial and angular arrangement and configuration of separated planing surfaces 203 and 208 reproducing the provisions of this invention, while distancing the planing surfaces from the bottom of the boat by means of hydrofoil-style struts 202, 601 and 602 brings additional advantages in terms of improvement in seaworthiness.

At the same time, taking into account that the struts of this embodiment support planing surfaces skimming along the surface of water, said hydrofoil-style struts 202, 601 and 602 made much shorter that results in less bulky design and much shallow draft in comparison with conventional submerged hydrofoils in the displacement mode, not to mention the negligible draft of planing surfaces in comparison with hydrofoils in the operational high-speed mode of motion.

This circumstance is added to the absence of cavitation as the main advantage of this hydrodynamic planing system over hydrofoils, which feature (in contrast to hydrofoils) eliminates all speed restrictions.

FIG. 7 is a schematic diagram that illustrates the perspective front bottom view of a boat according to some embodiments and basically corresponding to the embodiment of the FIG. 6, where the boat is provided with the hydrodynamic system featuring three cambered planing surfaces separated from the bottom of the boat.

In this embodiment the boat 201 is provided with two forward vortex-generating cambered planing surfaces 203 with their inner edges 303 and outer side deflectors 401, connected structurally with the bottom by means of struts 202, which surfaces 203 extend inward from the lower ends of the struts 202, while in order to strengthen the forward vortex-generating planes the inner tips of the surfaces 203 are supported here with additional struts 701.

The port and starboard cambered planing surfaces 203 set apart both sides of the boat's center plane and generate at their inner edges 303 two counter-rotating tip vortices, which create the ascending flow in the gap between said inner edges and further aft downstream the flow.

The boat 201 is provided also with the third separated aft cambered planing surface 208 arranged in the center plane of the boat 201 at some distance aft from the forward planing surfaces 203 and below the bottom of the boat 201 (above the bottom in this upside-down view), which aft cambered planing surface 208 features end deflectors 306 and structurally connected to the bottom of the boat 201 by means of the keel strut 601 and side struts 602.

Like in previously mentioned embodiments, vertical longitudinal sections of the separated aft planing surface 208 made conformal to the shape of the surface of the ascending flow and have the angular position taking into account the negative angle of inclination of the surface of the upward flow, which determines the spatial position of sections of the aft surface 208 above the base lines of the forward surfaces 203, the inclination of the base lines of the sections of the aft surface 208 nose-dive relative to the base lines of the forward surfaces 203 at the angles of inclination of the ascending flow, and the configuration of the aft surface 208 with gradually increasing from the central plane outward deadrise angles and moduli of negative angles of inclination of sections resulting in its half-planes curved upward and twisted downward in a substantially hyperbolic manner.

Through utilization of the above features of the ascending flow, the resulting configuration as well as spatial and angular position of the aft planing surface 208 relatively the forward planing surfaces 203 reduces the hydrodynamic drag of this system of the three planing surfaces and increases the efficiency of the boat 201.

By means of separation of the hydrodynamic system featuring three cambered planing surfaces 203 and 208 from the bottom of the boat 201, in this embodiment the bottom surfaces of the boat 201 are independent of the geometric shapes that are optimal for planing surfaces 203 and 208 and provided with much higher angle of deadrise (much higher than the angle of deadrise of planing surfaces) and this way ensure much sharper entry that should considerably upgrade seaworthiness of the boat 201 not sacrificing lift and hydrodynamic efficiency ensured by the spatial and angular arrangement and configuration of separated planing surfaces 203 and 208 reproducing the provisions of this invention, while distancing the planing surfaces from the bottom of the boat by means of hydrofoil-style struts 202, 601, 602 and 701 brings additional advantages in terms of improvement in seaworthiness.

At the same time, taking into account that the struts support planing surfaces skimming along the surface of water, said hydrofoil-style struts 202, 601, 602 and 701 made much shorter that results in less bulky design and much shallow draft in comparison with conventional submerged hydrofoils in the displacement mode, not to mention the negligible draft of planing surfaces in comparison with hydrofoils in the operational high-speed mode of motion.

This circumstance is added to the absence of cavitation as the main advantage of this hydrodynamic planing system over hydrofoils, which feature (in contrast to hydrofoils) eliminates all speed restrictions.

FIG. 8 depicts a schematic diagram illustrating one of possible embodiments of the normal to the plane along the flow section of the separated from the boat's bottom plane associated with the planing surface 203 and corresponding to the designation 1-1 of the embodiment of the FIG. 6.

In this drawing the section of the plane has its bottom part extending from the leading edge 801 up to the trailing edge 802, while the aft portion of this bottom is made concaved and represents the cambered planing surface 203.

As one of embodiments the planing surface 203 can reproduce a camber based on the Virgil Johnson three-term curve that was successfully applied to real planing surfaces in the past.

In operational mode of motion the cambered planing surface 203 skims along the surface of water and generates dynamic lift that supports the boat 201, and the planing surface 203 is the only surface of such section that supposed to contact the water at the operational speed of motion. Thus, basically, to fulfill its duty of dynamic support of the boat at the operational speed the lifting surface of this section should be limited by the bottom surface 203.

The embodiment shown in the FIG. 8 provided also with the streamlined convex upper surfaces 803 being similar to upper surfaces of hydrofoils.

The embodiment featuring the streamlined convex upper surfaces 803 can produce a double positive effect:

• • 1. At moderate speed of the boat corresponding transitional mode of motion (from floating displacement mode to purely planing mode) when the separated planing surfaces supposed to be completely submerged in water, the upper streamlined convex surfaces 803 is in contact with water and generates negative pressure resulting in additional hydrodynamic lift the same way as upper convex surfaces of hydrofoils that facilitates acceleration and take-off of the boat up to the transition to the purely planing mode. During motion at the operational speed in the purely planing mode said streamlined convex upper surfaces 803 will be excluded from generation of lift as they will be positioned above the level of water, will not contact the water (washed only by air and without any risk of cavitation) and will not affect operation of the planing surfaces.
  • 2. Providing the separated planing surfaces with the streamlined convex upper surfaces 803 makes them stronger structurally: The streamlined convex upper surface 803 increases the structural height of the section (in fact without increase in the drag) and, correspondingly, the moment of inertia and the moment of structural resistance of the section of planing surface that reduces bending stresses in the material of the separated planing surface made in the form of a cantilever structure, e.g.

This embodiment of the section shown in the FIG. 8 is provided also with flat portion 804 of the bottom surface between the leading edge 801 and the leading edge of the profiled portion of bottom of the section corresponding to the cambered planing surface 203, while this flat portion 804 may coincide with the hydrodynamic base plane of the cambered planing surface 203 that could be found useful to facilitate transition from the hydrofoil-assisted mode to the highly efficient purely planing one featuring wetted area being limited by the cambered planing surface 203.

FIG. 9 is a schematic diagram that illustrates the perspective aft bottom view of a boat employing the hydrodynamic system of three cambered planing surfaces arranged following this invention and integrated into boat's bottom according to some embodiments.

In this embodiment the boat 201 is provided with two sponsons 901 protruding downwards (upwards in this upside-down view) from the forward part of bottom of said boat and transversely spaced apart both sides of the center plane of said boat, while vortex-generating swept back cambered planing surfaces 203 with their inner edges 303 and outer side deflectors 401 are integrated into the aft bottom part of sponsons 901 and extend outwardly relative to the keel lines of the sponsons 901.

As bottom portions of the sponsons 901, the port and starboard cambered planing surfaces 203 spaced apart both sides of the boat's center plane generate at their inner edges 303 two counter-rotating tip vortices, which create the ascending flow in the gap between said inner edges and further aft downstream the flow.

The boat 201 is provided also with the third aft cambered planing surface 208 with deflectors 306 at the ends of its span, which surface 208 is arranged in the center plane of the boat 201 and integrated into boat's bottom at some distance aft from the forward planing surfaces 203.

Vertical longitudinal sections of the integrated into bottom aft planing surface 208 made conformal to the shape of the surface of the ascending flow and have the angular position taking into account the negative angle of inclination of the surface of the ascending flow, which determines the spatial position of sections of the aft surface 208 above the base lines of sections of the forward surfaces 203, the inclination of the base lines of the sections of the aft surface 208 nose-dive relative to the base lines of the forward surfaces 203 at the angles of inclination of the ascending flow, and the configuration of the aft surface 208 with gradually increasing from the central plane outward deadrise angles and moduli of negative angles of inclination of sections resulting in its half-planes curved upward and twisted downward in a substantially hyperbolic manner.

Through utilization of the above features of the ascending flow, the resulting configuration as well as spatial and angular position of the aft planing surface 208 relatively the forward planing surfaces 203 reduces the hydrodynamic drag of this system of the three planing surfaces and increases the efficiency of the boat 201.

In this embodiment span-limiting deflectors 306 of the aft planing surface 208 and the deflectors 401 at the outer sections of the forward vortices-generating planing surfaces 203 increase hydrodynamic pressure and lift of these planing surfaces (while corresponding raise in the lift coefficient of the forward planing surfaces 203 will result in a higher angle of slope of the ascending flow), reduce inductive drag (which is equivalent to increase in aspect ratio of these dynamic lift surfaces) and this way further improve efficiency of this hydrodynamic system and the boat 201 as a whole.

The integration of the planing surfaces 203 and 208 of this embodiment into the bottom surfaces of the boat 201 (namely, the aft portions of the sponson bottoms and the bottom of the main boat hull) allows the profiled planing surfaces 203 and 208 to be laminated and formed in one mold at once altogether with the boat hull, which can significantly simplify manufacturing of boats employing the hydrodynamic design of this invention.

FIG. 10 depicts a schematic diagram illustrating the front elevation view of a boat according to some embodiments, where the boat 201 is provided at its bottom part with three streamlined floats comprising two forward floats 1001 spaced apart relatively the center plane of the boat 201 and one aft float 1002 arranged at the center plane of the boat 201, while these floats support the boat 201 by Archimedean forces and keep it above the water level 1003 in the displacement mode when not moving or at low speed.

The boat 201 employs also the hydrodynamic system of three separated cambered planing surfaces according to this invention and comprising the two forward vortex- and ascending flow-generating planing surfaces 203 and the aft planing surface 208, which surfaces mounted on the bottom ends of the streamlined floats 1001 and 1002 correspondingly, and provided with convex upper surfaces 803.

Following provisions of this invention the planing surfaces 203 and 208 arranged spatially and angularly, and the aft planing surface 208 configured the way presupposing utilization of the ascending flow effect.

Taking into consideration the above, the boat 201 of this embodiment might have minimal hydrodynamic resistance and maximum efficiency in three consecutive modes of motion covering the full speed range of this boat:

• • 1. The minimum resistance and maximum efficiency in the displacement mode of motion at low Froude numbers ensured due to the low-drag movement in water of the only immersed streamlined floats 1001 and 1002.
  • 2. The minimum resistance and maximum efficiency in the transitional mode provided by high lift and efficiency of separated planes 203 and 208 with convex upper surfaces 803 being submerged in this mode and operating as hydrofoils (while moderate transitional speeds do not cause the problem of cavitation).
  • 3. The principal operational high-speed and highly efficient mode of motion when the boat 201 is supported exclusively by cambered planing bottoms of two forward planing surfaces 203 and one aft planing surface 208, which high efficiency is ensured by the use of the ascending flow effect, not having any speed limits caused by cavitation (since use of only planing bottom surfaces 203 and 208 generating only positive hydrodynamic pressures). In this principal operational mode the streamlined floats 1001 and 1002 as well as the convex upper surfaces 803 of the separated cambered planing surfaces 203 and 208 are excluded from generation of any lift. They supposed to be out of any contact with water and they do not affect the operation of planing surfaces 203 and 208. This way there could be achieved a smooth transition from low-speed modes of operation to high-speed ones and obtained gently sloping resistance vs. speed curve with low hump of a drag that in its turn should result in reduced power requirements, lower cost of the powerplant, longer range, etc.

In addition, supporting the hull of the boat 201 above the water level 1003 in the displacement mode by said streamlined floats 1001 and 1002 with a small waterline area will make the boat 201 less sensitive to wave impacts, which design can significantly suppress pitching and rolling of the boat 201 (that moreover should be vastly damped by surfaces of submerged separated planes 203 and 208) and substantially ameliorate the comfort of staying aboard.

To further facilitate take off of the boat 201 and enhance stability in the operational mode of motion, the bottom ends of the streamlined floats 1001 and 1002 can also be provided with supplementary hydrofoils or additional take-off planing surfaces 1004, which supposed to be out of contact with water during high-speed operation under low and moderate Sea State conditions.

In this embodiment the span of the aft planing surface 208 is limited by deflectors 306 and the forward vortices-generating planing surfaces 203 are provided with end plates 1005, which design features increase hydrodynamic pressure and lift of these planing surfaces (while corresponding raise in the lift coefficient of the forward planing surfaces 203 will result in a higher angle of slope of the ascending flow), reduce inductive drag (which is equivalent to increase in aspect ratio of these dynamic lift surfaces) and this way further improve efficiency of this hydrodynamic system and the boat 201 as a whole.

FIG. 11 depicts a schematic diagram that illustrates the rear perspective view of bottom of a boat (shown upside-down), which is basically close to the embodiment of the diagram 10, where a boat 201 is provided at its bottom part with three streamlined floats comprising two forward floats 1001 spaced apart relatively the center plane of the boat 201 and one aft float 1002 arranged at the center plane of the boat 201, while in this diagram the forward floats 1001 are structurally connected to the hull by means of struts 202.

The hydrodynamic system of three separated cambered planing surfaces according to this invention and comprising the two forward vortex—and ascending flow—generating planing surfaces 203 and the aft planing surface 208 are mounted on the bottom ends of the streamlined floats 1001 and 1002 correspondingly.

The combination of the low-drag streamlined floats supporting the boat 201 in the displacement mode with the hydrodynamic system of the three cambered planing surfaces 203 and 208 employing the ascending flow effect following this invention and serving as the dynamic support devices for the highly efficient high-speed operation (and moreover provided with not shown here hydrofoil-like upper surfaces for easier take-off), minimizes drag and ensures high efficiency of the boat 201 in all three consecutive modes of operation of the boat 201: —low-speed floating, transitional mode and the principal high-speed operation.

To facilitate take off of the boat 201 and coming to the operational high-speed planing mode, as well as to enhance stability in the operational mode of motion, the bottom ends of the streamlined floats 1001 and 1002 provided also with supplementary hydrofoils or additional take-off planing surfaces 1004, which supposed to be out of contact with water during high-speed operation under low and moderate Sea State conditions.

Similarly to the embodiment of the FIG. 10, the span of the aft planing surface 208 is limited by deflectors 306 and the forward vortices-generating planing surfaces 203 are provided with end plates 1005, which design features increase hydrodynamic pressure and lift of these planing surfaces (while corresponding raise in the lift coefficient of the forward planing surfaces 203 will result in a higher angle of slope of the ascending flow), reduce inductive drag (which is equivalent to increase in aspect ratio of these dynamic lift surfaces) and this way further improve efficiency of this hydrodynamic system and the boat 201 as a whole.

Suspension of the front floats 1001 under the bottom of the boat 201 by means of struts 202 forms a gap between the float 1001 and the hull of boat 201 and prevents slamming in the area where the internal surfaces of the floats 1001 attach the bottom in the embodiment shown in Diagram 10. In this way, this embodiment moderates the impact of waves, i.e., reduce structural loads and accelerations and thereby soften the ride in waves and increase the comfort of staying aboard during riding under high Sea States.

The penetration through large waves is further improved by the elongated streamlined cross sections of struts 202 oriented along the inclined flow created as a result of the interaction of the wave and the bottom surfaces of the boat 201, which oblique position of sections presupposes that their leading edges are located closer to the center plane of the boat 201 than the trailing edges.

The cross sections of struts 202 are provided also with a profile and angle of incidence ensuring, when interacting with a wave, generation of a pulling hydrodynamic force (i.e., some additional thrust), which further facilitates riding under rough sea conditions.

FIG. 12 depicts a schematic diagram illustrating the front elevation view of a boat of catamaran configuration according to some embodiments of this invention, where the catamaran boat 201 (shown in the displacement mode corresponding to the waterline 1003) has two hulls 1201 and equipped, in accordance with this invention, with the hydrodynamic system consisting of three separated cambered planing surfaces 203 and 208 with convex hydrofoil-like upper surfaces 803. Each of the two forward vortex-generating surfaces 203 mounted under the bottom of corresponding hull 1201 at its forward part and the aft separated cambered planing surface 208 positioned between the catamaran hulls 1201 in the aft part of the catamaran boat 201 and supported by the center plane strut 1202.

In the displacement mode and at low speed of motion the catamaran boat 201 is supported predominantly by Archimedean forces of hulls 1201 which keep the boat 201 floating at the water level 1003.

At higher speed of motion corresponding to the transitional mode, the separated cambered planing surfaces 203 and 208 start to generate some dynamic lift assisted by the lift produced by their still submerged hydrofoil-like convex upper surfaces 803.

At the principal high-speed operational mode of motion the hulls 1201 as well as the convex upper surfaces 803 are positioned above the water level and the catamaran boat 201 is supported exclusively by the dynamic lift generated by cambered bottoms of planing surfaces 203 and 208 arranged following the hydrodynamic design of this invention and exploiting the effect of the ascending flow generated by the forward planing surfaces 203 by means of special position and configuration of the aft planing surface 208, and ensuring this way low drag and high efficiency of the catamaran boat 201.

Endowing the dynamic support function with only separate planing surfaces 203 and 208 makes it possible to provide the hulls 1201 with very sharp formations that mitigates wave impacts and favorably affects the seaworthiness of the catamaran boat 201.

The outer tips of the aft planing surface 208 fastened on the inner surfaces of the catamaran hulls 1201. This completely stops the flow of water over the tip edges of the aft planing surface 208, eliminates tip losses and increases the efficiency of both the aft planing surface 208 and the catamaran boat 201 as a whole. In addition, the attachment of the outer tips of the aft planing surface 208 to the hulls 1201 increases the strength of this design as a whole.

To facilitate take-off of the catamaran boat 201 and enhance stability in the operational mode of motion, the lower bottom ends of the hulls 1201 provided with supplementary hydrofoils or additional take-off planing surfaces 1004, which supposed to be out of contact with water during high-speed operation under low and moderate Sea State conditions.

The forward vortices-generating planing surfaces 203 are provided with end plates 1005 and the span of the aft planing surface 208 is limited by deflectors 306, which design features (in addition to attaching the outer tips of the aft planing surface 208 to hulls 1201) increase hydrodynamic pressure and lift of these planing surfaces (while corresponding raise in the lift coefficient of the forward planing surfaces 203 will result in a higher angle of slope of the ascending flow), reduce inductive drag (which is equivalent to increase in aspect ratio of these dynamic lift surfaces) and this way further improve efficiency of this hydrodynamic system and the catamaran boat 201 as a whole.

FIG. 13 depicts a schematic diagram illustrating the front elevation view of a boat of catamaran configuration according to some embodiments and basically corresponding to the embodiment of the FIG. 12, where the catamaran boat 201 (shown in the displacement mode corresponding to the waterline 1003) has two hulls 1201 and equipped, in accordance with this invention, with the hydrodynamic system consisting of three separated cambered planing surfaces 203 and 208 with their end plates 1005, deflectors 306 and convex hydrofoil-like upper surfaces 803. Each of the two forward vortex-generating cambered surfaces 203 mounted on the bottom of corresponding hull 1201 at its forward part and the aft separated dihedral cambered planing surface 208 positioned between the catamaran hulls 1201 in the aft part of the catamaran boat 201 and supported by the strut 1202.

In this embodiment semi-submerged counter-rotating propulsion propellers 1301 with longitudinal axes and directions of rotation 1302 mounted on the inner tips and downstream of forward planing surfaces 203, so that the direction of rotation of the right-hand propeller is clockwise and the left one is counterclockwise when viewed from the front, while the axes of rotation of propellers 1301 are basically coaxial with the axes of the cords of vortices generated by the forward planing surfaces 203.

In high-speed operational mode, rotation of propellers 1301 corresponding directions 1302 leads to an additional upward component of the flow velocity vector in the gap between the forward planing surfaces 203, which upward component will increase the angle of slope of the ascending flow further downstream, resulting in the sections of the aft planing surface 208 tilted at a larger negative (nose-dive) angle, and thereby reduce drag and increase the hydrodynamic efficiency of the catamaran boat 201.

To facilitate take-off and the transitional mode of the catamaran boat 201 and enhance stability in the operational mode of motion, the bottom ends of the hulls 1201 provided with supplementary hydrofoils or additional take-off planing surfaces 1004, which supposed to be out of contact with water during high-speed operation under low and moderate Sea State conditions.

FIG. 14 depicts a schematic diagram illustrating the bottom plan view of the boat of catamaran configuration according to some embodiments and basically corresponding to the embodiment of the FIG. 13, where the boat 201 has two hulls 1201 and equipped, in accordance with this invention, with the hydrodynamic system consisting of three separated cambered planing surfaces 203 and 208. Each of the two forward vortex-generating cambered surfaces 203 mounted on the bottom of corresponding hull 1201 at its forward part and the aft separated dihedral cambered planing surface 208 positioned between the catamaran hulls 1201 in the aft part of the catamaran boat 201.

In this embodiment counter-rotating propulsion propellers 1301 mounted on the tips of the inner vortices-shedding edges and positioned downstream of forward planing surfaces 203, so that the axes of rotation of propellers 1301 are basically coaxial with the axes of the cords of shed vortices.

In high-speed operational mode, rotation of propellers 1301 leads to an additional upward component of the flow velocity vector in the gap between the forward planing surfaces 203, which upward component will increase the angle of slope of the ascending flow further downstream, resulting in the sections of the aft planing surface 208, to be conformal to the ascending flow, shifted vertically against the base lines of the forward planing surfaces 203 and tilted at a larger negative (nose-dive) angle, and thereby reduce drag and increase the hydrodynamic efficiency of the catamaran boat 201.

To facilitate take-off and the transitional mode of the catamaran boat 201 and enhance stability in the operational mode of motion, the bottom ends of the hulls 1201 provided with supplementary hydrofoils or additional take-off planing surfaces 1004, which supposed to be out of contact with water during high-speed operation under low and moderate Sea State conditions.

FIG. 15 depicts a schematic diagram illustrating the bottom plan view of the boat of catamaran configuration according to some embodiments, where the catamaran boat 201 has two hulls 1201 and equipped, in accordance with this invention, with the hydrodynamic system consisting of three separated cambered planing surfaces 203 and 208. Each of the two forward vortex-generating cambered surfaces 203 mounted on the bottom of corresponding hull 1201 at its forward part and the aft separated dihedral cambered planing surface 208 positioned between the catamaran hulls 1201 in the aft part of the catamaran boat 201.

In this embodiment counter-rotating propulsion propellers 1301 are supported by struts, brackets or propulsion drives 1501 and positioned between the forward vortex-generating surfaces 203 and aft planing surface 208 along the length of the boat in the wakes of tip vortices shedding from the edges 303 of forward surfaces 203, so that the axes of rotation of propulsion propellers 1301 basically coaxial the axes of the cords of shed tip vortices of the forward surfaces 203.

In high-speed operational mode, rotation of propellers 1301 leads to an additional upward component of the flow velocity vector in the gap between the forward planing surfaces 203, which upward component will increase the angle of slope of the ascending flow further downstream, resulting in the sections of the aft planing surface 208, to be conformal to the ascending flow, shifted vertically against the base lines of the forward planing surfaces 203 and arrange at a larger negative (nose-dive) angle, and thereby reduce drag and increase the hydrodynamic efficiency of the catamaran boat 201.

To facilitate take off and the transitional mode of the catamaran boat 201 and enhance stability in the operational mode of motion, the bottom ends of the hulls 1201 provided with supplementary hydrofoils or additional take-off planing surfaces 1004, which supposed to be out of contact with water during high-speed operation under low and moderate Sea State conditions.

FIG. 16 depicts a schematic diagram illustrating the front elevation view of a single-keel boat with foldable forward planes and propulsion drives according to some embodiments, where a boat 201 provided with a hydrodynamic system following this invention and comprising two forward vortex-generating cambered planing surfaces 203 separated from the bottom of the boat 201 and one center-plane-located aft cambered planing surface 208 integrated into the aft part of boat's bottom, so that the planing surfaces 203 and 208 arranged spatially and angularly, and the surface 208 configured in the way ensuring generation and use of the effect of the ascending flow in accordance with this invention, which embodiment results in low drag and high hydrodynamic efficiency of the boat 201.

The boat 201 provided with semi-submerged counter-rotating propulsion propellers 1301 with their directions of rotation 1302 supported by propulsion drives 1501 arranged similarly the configuration of the FIG. 15 along the length of the boat downstream the forward planing surfaces 203 and upstream the aft planing surface 208, so that the axes of rotation of propellers 1301 are basically coaxial with the axes of the cords of vortices shed from the forward planing surfaces 203.

As a result of this embodiment, in high-speed operational mode, rotation of propellers 1301 corresponding directions 1302 leads to an additional upward component of the flow velocity vector in the gap between the forward planing surfaces 203, which upward component will increase the angle of slope of the ascending flow further downstream, resulting in the sections of the aft planing surface 208, to be conformal to the ascending flow, shifted vertically against the base lines of the forward planing surfaces 203 and arrange at a larger negative (nose-dive) angle, and thereby reduce drag and increase the hydrodynamic efficiency of the boat 201.

In this embodiment each of the forward planing surfaces 203 is made foldable and connected structurally with the bottom not by fixed struts, but by means of double-rocker mechanism comprising rocking struts 1601 and hinges 1602 with longitudinal axes, which makes the forward planing surfaces 203 able to snuggle against the hull of the boat, while propulsion drives 1501 with propellers 1301 made capable of pivoting laterally upward around the longitudinal axes.

In this FIG. 16 both forward planing surfaces 203 and propulsion drives 1501 with propellers 1301 are shown in unfolded position corresponding principal high-speed operational mode of the boat 201.

Through separating the forward planing surfaces 203 from the bottom of the boat 201 the bottom surfaces of the boat at its bow part made with high angle of deadrise indicated by the dotted line 402 (much higher than the hydrodynamically optimum angle of deadrise of the plane 203), which ensure sharp entry considerably upgrading seaworthiness of the boat, but not sacrificing lift and hydrodynamic efficiency (provided by the hydrodynamically efficient design of this invention).

FIG. 17 depicts a schematic diagram illustrating the front elevation view of a single-keel boat according to some embodiments and basically corresponding to the embodiment of the FIG. 16, but with foldable forward planes and propulsion drives shown in the retracted position, where the boat 201 with its bow part made with large angle of deadrise indicated by the dotted line 402, provided with two forward cambered planing surfaces 203 separated from the bottom of the boat 201 and one center-plane-located aft cambered planing surface 208 integrated into the aft part of boat's bottom.

Like in the embodiment of the FIG. 16, in this embodiment each of the forward planing surfaces 203 made foldable and connected structurally with the bottom not by fixed struts, but by means of double-rocker mechanism comprising rocking struts 1601 and hinges 1602 with longitudinal axes, while in this figure the forward planing surfaces 203 shown snuggled against the hull of the boat and the propulsion drives 1501 with propellers 1301 pivoted laterally upward around the longitudinal axes, so that both the forward planing surfaces 203 and the propulsion drives 1501 with propellers 1301 do not protrude below the keel line and beyond the dimensions of the boat 201 as a whole, ensuring shallow draft in the displacement mode and trailerability.

As a variant of the shown embodiment, both the forward planing surfaces 203 and the drives 1501 with propellers 1301 in the folded position can be retracted into special recess niches on the bottom of the boat 201 to make them flush with the bottom surfaces.