HK1178862B - Watercraft with stepped hull and outboard fins - Google Patents

Description

Watercraft with stepped hull and outboard fins

Cross reference to related patent applications

This application claims priority to provisional application No.61/187644 filed on day 16, 6/2009, the entire disclosure of which is incorporated herein by reference.

Background

Such asAs properly described in U.S. patent No.6,666,160, "because one prefers to trade on water with a boat, he has attempted to design a hull with increased speed without unduly sacrificing stability. ' reducing ship bodyOne way of providing hydrodynamic drag thereon and thereby increasing the efficiency of the hull of a high performance watercraft is to provide a stepped hull in which the lower surface of the hull is not a smooth surface but includes a transverse step. By improving the performance characteristics above water, the graded hull can be used to improve the performance of the hull, thereby reducing the wetted surface of the hull. Stepped hulls have been known for many years, including, for example, U.S. patent No.1,121,006 to Fauber, U.S. patent No.1,858,030 to Batty, and U.S. patent No.6,250,246 to Hubley, each of which is incorporated herein by reference.

Fauber discloses a hull or "water ski section" having a plurality of stepped portions and an internal air duct system for conveying air under pressure to the stepped portions of the hull, for example using a drive IC engine as a pump to force air into the internal air duct system. Hubley discloses an internal air duct system having an inlet near the bow of the hull and an outlet in the surface of a step on the hull. These forced air systems help to avoid the creation of a vacuum in the stepped hull section and help to lift the hull out of the water, thereby reducing the wetted area.

However, the integration of the internal piping into the hull is complicated. In addition, a common problem with stepped hulls is that during turning, the watercraft may tend to rotate generally about a step on the hull, especially when the air system is being forced to lift the stern portion of the hull off of the water.

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

A high performance planing watercraft having a stepped hull is disclosed. A pair of outboard fins are secured to the hull sidewalls. The wing portions extend outwardly and downwardly toward the water surface. Preferably the fins extend at least down to the height of the stepped hull section. Each outboard wing defines a channel and is configured such that during planing operation the channel is inclined relative to the incoming air such that the air is compressed in the channel and thereby at least partially forced towards the stepped hull portion, thereby reducing wetted surface area. In horizontal operation, the outboard fins are relatively horizontal and flow through the channels will create a vacuum that helps maintain good contact of the graded hull portion with water.

In an embodiment of the watercraft, the wing is generally L-shaped having a first leg extending outwardly from the hull and a second leg extending downwardly from the first leg.

In an embodiment of the watercraft, a pair of oppositely disposed outboard strakes is attached to the stepped hull portion. The strakes may be tapered near the forward end to provide ports or flow paths to facilitate air flow to or from the stepped hull portions.

In an embodiment of the watercraft, the leading edge of the flap is in front of the stepped hull portion and extends to the transverse plate, for example, along 30% to 50% of the length of the hull.

In an embodiment of the watercraft, a second stepped hull portion is provided which is upwardly offset from the first stepped hull portion and may further include a second set of strakes along the outboard edge thereof.

Drawings

The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of a watercraft having a stepped hull with performance fins in accordance with the present invention;

FIG. 2 is a perspective view of the hull of the watercraft shown in FIG. 1 from the front, left side, and below;

FIG. 3 is a perspective view of the hull of FIG. 2 from the rear, left side, and below;

FIG. 4 is a front view of the hull of FIG. 2;

FIG. 5 is a left side view of the hull shown in FIG. 2; and

fig. 6 is a rear view of the hull shown in fig. 2.

Detailed Description

In fig. 1 a high performance watercraft 99 according to the present invention is shown operating at planing speed. The watercraft 99 includes a stepped planing hull 100 having oppositely disposed ports and outboard performance fins, referred to herein as ram air fins 120, located on the aft end portion of the hull 100, 100. Ram air fins 120 extend longitudinally along the stepped portion of the hull 100. The exemplary embodiment generally corresponds to apostle (tm) series high performance watercraft manufactured by safe assets International l.l.c. (www.safeboats.com), although one skilled in the art can apply the present invention to a variety of watercraft.

In the current embodiment, the hull 100 is formed primarily of aluminum and may be, for example, from 29 feet to 42 feet in length. Other hull sizes are also contemplated. Optional foam sponsons 98 are shown disposed around the upper perimeter of the hull 100. A console 96 with operator controls is provided substantially in the middle of the boat and a plurality of outboard motors 95 (four shown) provide propulsion. It will be apparent to those skilled in the art that other lengths, materials of construction, numbers and types of motors, etc. may be used without departing from the invention.

The stepped hull 100 of the watercraft 99 is shown in fig. 2-6. Fig. 2 shows a perspective view of the hull 100 from a perspective view point of substantially anterior-left-inferior, and fig. 3 shows a perspective view from a perspective view point of substantially posterior-left-inferior. The hull 100 is a planing V-hull having a central keel 101, a first step 102 and a second step 104. The hull may be, for example, a half V, a modified V, a large depth V, etc. Although the hull 100 includes two steps, those skilled in the art will appreciate that a single step or more than two steps may alternatively be provided without departing from the invention.

The hull comprises a forward hull portion 103 located forward of the first step 102. The first step 102 delimits a first stepped hull portion 106 and the second step 104 delimits a second stepped hull portion 108. Although not required by the present invention, the hull 100 includes an upper flange 90 and a lower flange 92 for mounting a foam sponson 98 (see FIG. 1), such as the foam stabilized watercraft disclosed in the inventor's U.S. Pat. No.5,282,436, which is incorporated herein by reference in its entirety. Although the present embodiment of the invention is applied to the foam-stabilized watercraft 99, the invention can be adapted to a hull without such a sponson.

The first stepped hull portion 106 includes oppositely disposed first outboard strakes 110, one on the port side of the first stepped hull portion 106 and the other on the starboard side of the first stepped hull portion 106. Similarly, the second stage hull portion 108 includes oppositely disposed second outboard strakes 112 (one visible), one on the port side of the second stage hull portion 108 and the other on the starboard side of the second stage hull portion 108. In this embodiment, the outboard strakes 110, 112 are located at the hull bilge line 109 (or define a portion of the hull bilge line 109), such as where the sidewalls 114 meet the stepped hull portions 106 or 108.

In a presently preferred embodiment, the forward end or forward end portion 111 of the first outboard strake 110 and the forward end or forward end portion 113 of the second outboard strake 112 are tapered. The tapered leading ends 111, 113 may optionally be spaced apart from the associated first and second steps 102, 104. The tapered nose portions 111, 113 define ports that provide a flow path or ports for air to enter beneath the hull 100 near the steps 102, 104.

Referring now also to fig. 4, 5 and 6, fig. 4 shows a front view of the hull 100, fig. 5 shows a left side view of the hull 100, and fig. 6 shows a rear view of the hull 100. Oppositely disposed and outwardly extending ram air fins 120 are attached to the port and starboard side walls 114 of the hull 100 generally along the stepped hull portions 106, 108. The ram air wing 120 is a generally L-shaped or arcuate elongated structure that extends outwardly and downwardly from the side wall 114. For convenience, the ram air wing 120 may be fixed to the lower flange 92 or integrally formed with the lower flange 92. For example, the ram air wing 120 may be welded to the watercraft 99. As best shown in fig. 4, the ram air fins 120 cooperate with the hull sidewalls 114 to define downwardly open channels 130. The ram air wings 120 are preferably dimensioned such that the distal edges 122 of the ram air wings 120 extend at least down to a level defined by the lower edges of the outboard strakes 110, 112. In the present hull 100, the ram air fins 120 extend down slightly beyond the height of the strakes 110, 112.

The leading edge 124 (fig. 5) of each ram air wing 120 is preferably located forward of the first step 102 and optionally extends substantially to the diaphragm or trailing end 116 of the hull 100. For example, the ram air wing 120 may extend up to 30% to 50% of the length of the hull 100 along the aft end.

The function of the watercraft 99, and in particular the ram air wing 120, will now be described. As the hull 100 moves forward through the water, air enters the channel 130 defined by the ram air fins 120. The incoming air is directed at least partially underneath the hull 100, particularly underneath the first and second hull sections 106, 108.

The planing hull 100 is configured to lift the bow of the watercraft out of the water as the watercraft 99 is operated at higher speeds (e.g., in a substantially straight line). The hydrodynamic forces lift the bow of the planing hull 100 off the water surface so that the angle of inclination of the hull relative to the water surface increases, i.e. the angle of attack increases as the hull 100 pivots about a horizontal transverse axis. It will be appreciated from fig. 1 that the angle of the ram air wing 120 fixed to the hull 100 relative to the direction of travel also increases. The increased angle of attack causes the air entering the channel 130 to be diverted downwards by the inclined surface of the ram air wing 120, so that the air pressure in the channel 130 increases.

The higher air pressure in the passage 130 increases the airflow through the ports defined by the outboard strakes 110, 112 at the first and second steps 102, 104, so that air is forced under the first and second stepped hull portions 106, 108. The increased airflow under the stepped hull portions 106, 108 helps to reduce the surface area that is effectively wetted, thereby reducing hydrodynamic drag on the hull 100, improving performance. Furthermore, it is believed that the hydrodynamic force of the inclined ram air wing 120 will create an upward force on the ram air wing 120, which will further assist in lifting the hull 100 out of the water and reduce the wetted area when the hull 100 is in planing mode.

The reason for the tapered and spaced apart front ends 111, 113 of the first and second strakes 110, 112 will now be understood. In the present embodiment, the ports defined by the tapered first and second strakes 110, 112 provide a means for preferentially directing air under the hull 100, compressed by the ram air fins 120 as described above, near the first and second steps 102, 104.

In addition to improving the performance of the hull 100 during planing operation, the ram air fins 120 also improve control of the watercraft 99 during turning. As mentioned above, a common problem with prior art stepped hull watercraft is that when an operator turns the watercraft hull, the hull will undesirably pivot generally about the step of the hull in some situations. It is believed that the reason for this is that the stepped portion of the hull only partially contacts the water surface, causing the hull to hydrodynamically react as if the step were the aft end of the hull or the diaphragm. This undesirable effect occurs even when the watercraft is balanced (trim) for substantially horizontal operation.

However, in the hull 100 disclosed herein, when the hull 100 is balanced to a level at which turning begins, the inclination or angle of attack of the hull decreases. When the angle of inclination of the hull 100 is reduced, the ram air fins 120 move towards a horizontal orientation, so that no inclined surface with respect to the local air flow is present anymore. The air flowing through the passages 130 is no longer compressed and thus the tendency for air to flow into the stepped hull portions 106, 108 is reduced or eliminated. Furthermore, in horizontal operation, the channel 130, now located near the waterline, will allow water to flow through. Due to Bernoulli's principle, water flowing through the channel 130 will create a vacuum at the port defined by the outboard strakes 110, 112. The vacuum assist provided by the bernoulli principle advantageously ensures that the stepped hull portions 106, 108 are in good contact with the water, reducing or eliminating any tendency of the watercraft to pivot or turn about one of the steps 102, 104. Thus, the ram air fins 120 disclosed herein have the highly desirable effect of forcing air into the stepped portions 106, 108 of the hull during planing operation, and drawing air out from under the stepped portions 106, 108 of the hull when the watercraft 99 is in relatively horizontal operation.

In addition, during turning of the watercraft 99, the tendency of the hull to yaw is offset by the ram air fins 120. Specifically, the ram air wing 120 located inboard of the turning radius will hydrodynamically resist the tendency to submerge into the water. Ram air wing 120, which is located outward from the turning radius, may generate a downward force as outboard wing 120 moves out of the water. As a result, the hull 100 will remain relatively level with respect to the water surface. Thus, the first and second hull sections 106, 108 will serve to remain in contact with the water and the hulls will turn in a very stable and predictable manner even at higher speeds.

While the illustrated embodiments have been shown and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.

Claims (13)

1. A high performance watercraft, comprising:

a V-shaped planing hull having a port side, a starboard side, a forward hull portion, and a first step defined at a trailing end of the forward hull portion, the first step defining a first stepped hull portion offset from the forward hull portion, the port and starboard sides and the first stepped hull portion together forming a hull bilge margin line;

a port outboard strake at said hull bilge line and a starboard outboard strake at said hull bilge line, wherein a forward end of said port outboard strake and a forward end of said starboard outboard strake are tapered, said tapered forward ends each defining a flow path between the outboard strake and said first step for air to enter or exit said hull near said first step;

a first ram air wing secured to the port side of the hull, the first ram air wing having a leading edge disposed forward of the first step, wherein the first ram air wing extends from above the first step to at least the first stepped hull portion; and

a second ram air wing fixed to the starboard side of the hull, the second ram air wing having a leading edge disposed forward of the first step, wherein the second ram air wing extends from above the first step to at least the first stepped hull portion;

wherein each of the first and second ram air wings define an outboard channel, and further wherein during planing operation of the watercraft the first and second ram air wings are inclined with respect to horizontal such that air entering the outboard channel is aerodynamically pressurized, and further wherein during horizontal operation of the watercraft the first and second ram air wings are not inclined with respect to horizontal such that water entering the outboard channel generates a vacuum pressure to draw air out from under the hull through the flow path; and is

Wherein the first and second ram air fins each comprise a first leg extending outwardly from the hull and a second leg extending downwardly from the first leg.

2. The high performance watercraft of claim 1 wherein the first ram air wing and the second ram air wing are secured along a trailing end of the watercraft.

3. The high performance watercraft of claim 2 wherein the first and second ram air wings extend to a cross plate of the watercraft.

4. The high performance watercraft of claim 3 wherein the first and second ram air fins extend along 30% -50% of the length of the hull.

5. The high performance watercraft of claim 1 further comprising a second step defined at a trailing end of the first stepped hull portion, the second step delimiting a second stepped hull portion that diverges upwardly from the first stepped hull portion.

6. The high performance watercraft of claim 5 further comprising a second pair of oppositely disposed outboard strakes secured to the second stepped hull portion.

7. A watercraft, comprising:

an aluminum hull having port and starboard side walls, said hull further including a forward hull portion and a first stepped hull portion offset upwardly from said forward hull portion, said port and starboard side walls forming a hull bilge edge line with said first stepped hull portion;

a port outboard strake at said hull bilge line and a starboard outboard strake at said hull bilge line, wherein a forward end of said port outboard strake and a forward end of said starboard outboard strake are tapered, said tapered forward ends each defining a flow path between the outboard strake and said first stepped hull portion for air to enter or exit said hull proximate said first stepped hull portion;

a port arcuate wing portion extending outwardly from the port side wall and at least downwardly to the first hull section; and

a starboard arcuate wing portion extending outwardly from the starboard side wall and at least downwardly to the first hull section;

wherein the port arcuate wing portion defines a downwardly open elongate channel extending along a portion of the port side wall adjacent the first hull portion and the starboard arcuate wing portion defines a downwardly open elongate channel extending along a portion of the starboard side wall adjacent the first hull portion;

wherein the port and starboard arcuate wing portions are configured to compress air during planing operation of the watercraft such that air entering the elongate channel is urged below the first stepped hull portion, and wherein further, during horizontal operation of the watercraft, the port and starboard arcuate wing portions are not inclined relative to horizontal such that water entering the elongate channel creates a vacuum pressure to draw air from below the hull through the flow path; and is

The port and starboard arcuate wing portions are generally L-shaped including a first leg extending outwardly from the hull and a second leg extending downwardly from the first leg.

8. The watercraft of claim 7 wherein the port and starboard arcuate wing portions are angled such that the arcuate wing portions are substantially horizontal when the watercraft is in an equilibrium horizontal configuration.

9. The watercraft of claim 7 wherein the port and starboard arcuate wing portions are secured along a trailing end of the watercraft.

10. The watercraft of claim 9 wherein the port and starboard arcuate wing portions extend to a transverse plate of the watercraft.

11. The watercraft of claim 7 wherein the watercraft further comprises a foam sponson disposed along the upper perimeter of the port side wall and the starboard side wall.

12. The watercraft of claim 7 wherein the hull further comprises a second stepped hull portion offset upwardly from the first stepped hull portion.

13. The watercraft of claim 12 further comprising a third strake secured to an outboard port edge of the second stepped hull portion and a fourth strake secured to an outboard starboard edge of the second stepped hull portion.