GB2024732A - Planing hulls - Google Patents

Abstract

A planing hull 10 has a substantially planar bottom surface 22 located over the aft section on which the hull planes at high speeds, a substantially V-shaped bottom surface 16 extending from the bow along a major portion of the length of the hull and a smooth convexly shaped transitional bottom surface portion 20. The planar surface 22 extends substantially the full width of the hull 10 and may be provided with a step at its rear most portion to move the centre of gravity of the hull aft. The planing surface 22 may also be provided with a plurality of steps to reduce the amount of wetted surface. <IMAGE>

Description

SPECIFICATION Hull with convexly down-step plane BACKGROUND OF THE INVENTION This invention is directed to a hull for boats, ships and the like. More particularly, the present invention is directed to a hull for water craft which has a substantially V-shaped forward or bow section and a substantially planar aft section connected together by a smooth convexly shaped transition section.

SUMMARY OF THE INVENTION The present invention is directed to a hull for water craft which has a lower water engaging surface terminated at one end by a bow and at the other end by a stern. Starting at the bow and extending for a major portion of the hull in the direction of the stern, the hull is provided with a V-shaped cross-section, preferably with each side of the "V" having a concave side. The V-shaped section has an apex running longitudinally along the hull centered with respect to the width of the hull. The apex is of a substantially constant depth for a substantial portion of the length of the V-shaped section. A substantially planar surface is provided in the aft portion of the hull. The planar surface is down-stepped from the apex of the V-shaped section. By down-step, it is meant that the planar section would extend deeper into the water.The-V-shaped section and the planar section are connected by a smooth convexly shaped transition section. The transistion section is convex in both the longitudinal and transverse directions.

In a preferred embodiment, the planar section extends substantially the full width of the hull.

Where the hull is used in a boat or ship structure, a major portion of the weight of the load and equipment of the ship or boat would be positioned over the planar section.

The convexly down-stepped planar section enables an increase in the attainable speed of the water craft in an extremely simple manner. The convexly down-stepped planar section also reduces the amount of power required to drive the water craft through or over the water thereby reducing fuel consumption and allowing the reduction in the amount of fuel required to be stored in the water craft for a pre-determined range of travel. This enables a reduction in the amount of weight or load which has to be allocated for the carrying of fuel, more load or passenger space, and a reduction in the weight allocated for engines as less powerful and lighter engines may be used.

The forward V-section, the smooth convexly shaped transition section and the planar section enable the lifting of a large portion of the water craft out of the water, thereby reducing the water resist ance. Hulls built in accordance with the present invention will also handle water much better than a hydrofoil, the deep and modified "V" hulls, stepped hull, tunnel or pontoon and the hovercraft.

Hulls built in accordance with the present invention are faster, more stable, more economical to operate because of the reduced water resistance and provide more usable space above the planar section of the water craft. The additional stability is provided because of the planar aft section. At no -planing speeds, the down-stepped planar section will give great lateral resistance. The hull of the present invention will also provide a smoother ride due to the wave cutting action of the forward V-section and the substantially planar aft section. The convex transition surface tends to force the water into the section where the propeller would be located. This tends to reduce any cavitation effects.

The convexly down-stepped hull of the present invention provides additional stability because of the combination of the planing surface connected with the forward V-section by a smooth transition section.

This combination of structure provides an improved angle of attack on waves when planing as the bow section is raised. The hull in accordance with the present invention provides a significant advantage in travelling through large waves. This is especially the case where the length of the forward "V-shaped" section exceeds or is at least equal to the distance between the trough and the crest of the wave. This requirement is usually met where the hull of the present invention is used on larger ships and tankers. Large waves are not usually encountered when the hull is used on smaller speed craft used for sport, enjoyment and pleasure.

The hull in accordance with the present invention is extremely stable at rest due to the flat submerged surface. At high speeds, the hull will plane thereby reducing the resistance to movement through and over the water. The hull of the present invention has a large prismatic coefficient and therefore much less resistance when planing, but without the loss of interior space.

In one embodiment of the present invention, narrow longitudinally extending members project from the bottom of the planing section substantially parallel to the center line of the hull. In a preferred embodiment, one would extend along the right or starboard edge of the planing section and another would extend along the left or port side of the planing section. These members act as small keels to increase the turning stability of the hull with very little added resistance.

The rearmost portion of the planing surface may be provided with an upward step, which may be referred to as a balance step, to move the center of gravity of the hull aft. This is particularly important where the hull may be used for freight ships, tanker ships and the like carrying substantial loads. The balance step also produces a smaller wetter surface when the hull is planing.

The planing surface may be provided with steps with or without the use of a balance step. The steps on the planing surface reduce the amount of wetted surface and provide increased stability and economy of operation. The steps on the planing surface may be slanted upward towards the bow of the boat.

Alternatively, the steps of the planing surface may be progressive, that is, each succeeding step towards the rear of the boat rising by a pre-determined amount.

It is understood that the present invention may be used with hard or soft chines. Other features may be incorporated into the hull, such as a cavity or tunnel for the drive propeller. Furthermore, the planing surface of the hull need not be completely flat, but may be somewhat "V" shaped, and the planing strakes may be used to enhance the planing abilities of the hull.

BRIEF DESCRIPTION OF THE DRA WINGS For the purpose of illustrating the invention,-there are shown in the drawings forms which are present lypreferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

Figure 1 is a view in perspective of a hull in accordance with the present invention.

Figure 2 is a side elevation view of a hull in accordance with the present invention, and also shows in dotted outline a modification of the hull as shown in Figure 6.

Figure 3 is a bottom view of a hull in accordance with the present invention.

Figure 4 is a cross sectional view taken along line 4-4 of Figure 2.

Figure 5 is a cross sectional view taken along line 5-5 of Figure 2.

Figure 6 is a rear elevation view of a hull in accordance with the present invention showing a modification thereof in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, wherein like numerals indicate like elements, there is shown in Figure 1 a perspective view of a hull 10 in accordance with the present invention. The hull 10 may be used on any type of watercraft including speed craft, yachts and ocean going vessels such as tankers.

Hull 10 is provided with a bow 12 and a stern 14.

The inventive shape of the present invention may be best understood by considering Figures 1, 2, 3 4 and 5together.Theforward portion ofthe hull is provided with a substantially V-shape in cross section portion 16 as may be most clearly seen in Figure 4. As may be seen in Figure 4, the sides 17 and 19 ofthe V-shaped portion 16 are concave. The substantially V-shaped portion 16 hasa longitudinaly running apex 18 which is centered or substantially centered with respect to the width of the hull. In other words the apex 18 preferably is formed halfway between the left or port side 24 and the right or starboard side 26 of the hull. The substantially V-shaped portion extends from the bow 12 rearward for a major portion of the length of the hull.

Preferably, the length of the substantially V-shaped portion is from about approximately 50% to about 67% of the length of the hull, with a major portion of the V-shaped portion being of substantially constant depth.

The rearward end of the V-shaped portion 16 terminates in a smooth convexly shaped transition section 20. Transition section 20 extends from the rear end 28 of the V-shaped portion 16 to the forward end 30 of the planing surface 22. The transition section 20 near the forward end 30 ofthe planing surface 22 is convexiy downstepped. The transition surface 20 is smooth, or in other words, in mathematical terms, does not have any discontinuities. Expressed differently, the transition section does not have any angles or sharp edges, but forms a smooth continuous longitudinally and transversely convexly shaped transition section.

The bottom of the rearward portion of the hull is a substantially planar surface 22 extending substantially the full width of the hull, that is substantially from port side 24to starboard side 26, and extending from the stern 14 forward for a distance of from approximately one-third to one-half of the length of hull 10.

Another embodiment of the invention is shown in Figure 6 in which the planing surface 22 of the hull is provided with at least one, preferably a pair of longitudinally downwardly extending members 34 and 36. The longitudinally and downwardly extending members 34 and 36 may extend substantially the full length of the planing section 22 as shown in dotted lines in Figure 2. The members 34 and 36 may have a rearwardly downwardly extending forward edge to reduce resistance. The longitudinally and downwardly extending members 34 and 36 act as narrow keels providing very little added resistance while increasing the turning stability of the hull.

These keels 34 and 36 are preferably placed as shown in Figure 6 in substantial alignment with the sides of the hull along the port and starboard side.

In use, a major portion of the loading of the hull is placed above the planing section 22 whether the boat be used as a speed boat, pleasure craft, yacht or ocean going vessel. When a hull is stopped in the water or at very low speeds, the hull will sink for a substantial portion of the hull height into the water wherein at least a portion oftheV-shaped section 16 will ride down into the water. When the hull is operated at normal speeds, which are faster than conventional water craft in use today, the hull will rise up and ride on the planing surface 22. Except for wave contact, at the higher speeds, the forward portion or V-shaped section 16 of the hull will ride out of the water. The planing surface forms a desirable angle of attack with the water at these higher speeds.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.

Claims (10)

1. A hull having a lower water engaging surface terminated at one end by a bow and at the other end buy a stern, the forward portion of said hull being substantially V-shaped in cross-section with the apex of the V-shape centered with respect to the breadth of said hull extending from said bow along a major portion of the length of said hull, a substantial ly planar surface downstepped from said apex of said V-shaped portion being formed in the aft portion of said hull and a smooth convexly shaped transition section connecting said V-shaped section and said substantially planar section.

2.. A hull in accordance with claim 1 wherein said planar section extends substantially the full width of the lower section of said hull.

3. A hull in accordance with claims 1 wherein a major portion of the weight carried by said hull is positioned over said planar section.

4. A hull in accordance with claim 1 wherein said planar surface is provided with at least one longitudinally downwardly extending member, said downwardly extending member being substantially parallel to the center line of the hull and being narrow with respectto the width of said hull.

5. A hull in accordance with claim 4 including a second downwardly extending member, one of said downwardly extending members extending along the port edge of said planar surface and the other of said downwardly extending members extending along the starboard edge of said planar surface.

6. A hull in accordance with claim 1 wherein the sides of said V-shaped portion are concave.

7. A hull in accordance with claim 1 wherein the aft portion of said planing section is provided with at least one upward step on said planing section.

8. A hull in accordance with claim 1 wherein said planing section is provided with a single upward step on its rearmost portion.

9. A hull in accordance with claim 1 wherein said planing section is provided with a plurality of steps.

10. A hull substantially as hereinbefore described with reference to the accompanying drawings.