WO2009051790A1

WO2009051790A1 - Water craft

Info

Publication number: WO2009051790A1
Application number: PCT/US2008/011864
Authority: WO
Inventors: Jayden David Harman
Original assignee: Pax Scientific, Inc.
Priority date: 2007-10-18
Filing date: 2008-10-17
Publication date: 2009-04-23
Also published as: WO2009051793A1

Abstract

A hull (12) of a water craft (11 ) adapted to float on a body of water for traversal thereof, the hull (12) having an external surface which in use contacts the body of water, wherein at least a substantial portion of the external surface has a curvature wherein the curvature substantially conforms to a logarithmic curve.

Description

"Water Craft"

Field of the Invention

The present invention relates to a water craft such as a boat and it is particularly applicable to small boats. Nevertheless the scope of the invention disclosed is not limited to the size or type of craft and thus may be applied far more generally than the embodiment described. In addition, the inventive concepts herein disclosed have application in fields wider than boats and the invention is not limited to such applications.

Background Art

It has long been appreciated that the shape of a water craft affects its performance in travelling thorough water. Conventionally, vessels have been provided with a relatively elongate hull having some form of tapered bow to reduce the resistance in attacking the water and maintain stability. To a significant extent, the shape of conventional vessels have evolved from need for the hull to be able to support the vessel and its load in the water whilst keeping the centre of gravity as low as possible for stability, in what is usually referred to as a displacement hull. This general shape of vessel has been used across the range of vessel sizes.

In more recent times, a range of vessels have been devised with the object of reducing the effect of drag on a hull. Examples include catamarans, trimarans, and hydrofoil craft. Nevertheless, while these are suitable for many purposes, they have limitations, especially for small powered craft.

Water craft such as small boats have generally been constructed from aluminium or fibreglass and before that from timber. These materials are used primarily as an external, waterproof skin and invariably require an internal frame to provide at least a substantial proportion of the hull strength. Craft made of these materials are relatively heavy and expensive and have other problems. Attempts have also been made to provide inflatable craft, but these also have had their own limitations. The present inventor has previously disclosed in US 5,517,939 (WO 9211179) a boat having a hull formed from polycarbonate, acrylic or similar material and side skirts fastened to the hull bottom in the form of tapered inflatable tubes which has not required an internal frame. While this craft provided a number of advantages, and in particular provided a very agile vessel, the inventor has now become aware of technological advances to provide a vessel with further improvements.

Disclosure of the Invention

Accordingly, the invention resides in a hull of a water craft adapted to float on a body of water for traversal thereof, at least a substantial proportion of the hull being formed from a material of substantially uniform thickness wherein the material has curvature which conforms to a logarithmic curve.

It is a preferred feature that the radius of the logarithmic curve unfolds at a constant order of growth when measured at equiangular radii, that is, that the curvature conforms to the Golden Section.

According to a preferred feature of the invention, the hull is formed without a frame for stiffening and/or strengthening the hull.

According to a further aspect, the invention resides in a hull of a water craft adapted to float on a body of water for traversal thereof, the hull having an external surface which in use contacts the body of water, wherein at least a substantial portion of the external surface has a curvature which conforms to a logarithmic curve.

It is a preferred feature that the radius of the logarithmic curve unfolds at a constant order of growth when measured at equiangular radii. According to a further aspect the invention resides in a water craft comprising a hull as previously described.

According to a preferred feature of the invention, the water craft is provided with stabilizing pontoons associated with the sides of the hull.

According to a preferred embodiment the pontoons are buoyant. According to a preferred embodiment the pontoons are formed from floatation material. According to a preferred embodiment, the pontoons are formed from a foamed thermoplastics material. According to a preferred embodiment, the pontoons are inflatable. According to a preferred embodiment, the pontoons are hollow. According to a preferred embodiment the pontoons take a streamlined shape. According to a preferred embodiment, the rear of the pontoons extend beyond the stern of the hull. According to a preferred embodiment, the pontoons take a bulbous form extending longitudinally from a reduced cross-section or apex at the rear to an enlarged lateral cross-sectional profile proximate the stern of the hull, and thereafter reducing in lateral cross-section to a position intermediate the stern and the bow of the hull. According to a preferred embodiment external outline of the longitudinal cross- sectional profile of the pontoons is curved, . According to a preferred embodiment the forward end of the pontoon extends into a formation providing a rim for the bow of the hull.

In accordance with a preferred embodiment, the pontoons are engaged with the sides of the hull in a manner to provide a continuously curved surface between the external surface of the hull and the external surfaces of the pontoons.

In accordance with a preferred embodiment, the hull is provided with stabilizing pontoon-like formations integrally formed with the sides of the hull. According to a preferred embodiment the pontoon-like formations take a streamlined shape. According to a preferred embodiment, the rear of the pontoon-like formations extend beyond the stern of the hull. According to a preferred embodiment, the pontoon-like formations take a bulbous form extending longitudinally from a reduced cross- section or apex at the rear to an enlarged lateral cross-sectional profile proximate the stern of the hull, and thereafter reducing in lateral cross-section to a position intermediate the stern and the bow of the hull. According to a preferred embodiment external outline of the longitudinal cross-sectional profile of the pontoon-like formations is curved. According to a preferred embodiment the forward end of the pontoon-like formations extends into a formation providing a rim for the bow of the hull.

According to a preferred feature of the invention, the water craft is provided with a cowling overlying the bow section of the hull, a substantial portion of the cowling taking the form of a compound curvature conforming with an equiangular spiral. According to a preferred embodiment, the curvature of the substantial portion of the cowling conforms with the Golden Section.

The invention will be more fully understood in the light of the following description of two embodiments.

Brief Description of the Drawings

The description is made with reference to the accompanying drawings, of which:

Figure 1 is an upper rear isometric of the first embodiment;

Figure 2 is an upper front isometric of the first embodiment;

Figure 3 is a lower front isometric of the first embodiment;

Figure 4 is a lower rear isometric of the first embodiment;

Figure 5 is a side elevation of the first embodiment; Figure 6 is a top plan view of the first embodiment;

Figure 7 is a bottom plan view of the first embodiment;

Figure 8 is a front elevation of the first embodiment;

Figure 9 is a rear elevation of the first embodiment;

Figure 10 is a longitudinal, sectional elevation of the first embodiment;

Figure 11 is a lateral cross-section of the first embodiment through section line A-A as indicated on Figure 6;

Figure 12 is a lateral cross-section of the first embodiment through section line B-B as indicated on Figure 6;

Figure 13 illustrates the form of the Golden Section; and

Figure 14 is an upper front isometric of the second embodiment.

Detailed Description of Preferred Embodiment

The first embodiment of the invention is directed to a boat constructed in accordance with the principles devised by the inventor. The embodiment is described with reference to Figures 1 to 13.

The first embodiment as shown in figures 1-13 comprises a boat 11. The boat 11 comprises a hull 12, a cowling covering the bow section 15 of the hull to provide a foredeck 14, and a pair of flotation pontoons 16 disposed towards the rear and at each side of the hull 12. A windscreen 17 is provided at the rear of the foredeck in conventional manner.

The hull 12 is formed from a suitable material as is discussed below, in the first embodiment, the material having a generally uniform thickness. The hull 11 has a bow section 15, a stern 18 and an intermediate portion 19 between the bow 15 and the stern 18. The hull 11 is formed to provide an upper peripheral edge and an external surface in contact with the water having a three dimensional, compound curvature. The bow section 15 extends forwardly and upwardly from the intermediate portion 19 in a compound curve that leads to a forward-most point 21 at the peripheral edge. As best shown in the bottom plan view, Figure 7, this forward-most point is merely a point on the curved peripheral edge and does not take a pointed form. Such a form could be taken if desired for aesthetic reasons but is not necessary, functionally.

As shown in the longitudinal cross-section, Figure 10, the intermediate portion 19 extends with a slight curvature towards the stern 18, and is also curved towards the sides. The stern 18 acts to terminate the intermediate portion 19 and provide a transom 22 upstanding from the hull 12 to provide a support for an outboard motor. Alternatively, a jet-type motor can be used.

It is a feature of the embodiments that at least a substantial proportion of the hull is formed from a material of substantially uniform thickness wherein the material has curvature which conforms to a logarithmic curve. It is a preferred feature that the radius of the logarithmic curve unfolds at a constant order of growth when measured at equiangular radii, that is, that the curvature conforms to the Golden Section. As a result of this feature, it is a characteristic of the hull that it does not have a central, vee-shaped keel line. As will be discussed below, this compound curve conforming generally to an equiangular logarithmic curve provides the craft with improved characteristics of strength and stiffness. It is also a feature of the embodiments that at least a substantial proportion of the external surface of the hull which contacts the water body has a curvature which conforms to a logarithmic curve. It is a preferred feature that the radius of the logarithmic curve unfolds at a constant order of growth when measured at equiangular radii, that is, that the curvature conforms to the Golden Section.

The flotation pontoons 16 are engaged with the sides 23 of the hull to form the sides of the boat. The flotation pontoons 16 have a bulbous or pod shaped appearance as may be appreciated from the drawings. The lateral cross-sectional form of each pontoon is approximately circular throughout the length of the pontoon but the diameter varies from an apex 24 at the rear to a maximum 25 a little forwardly of the transom and receding to a small diameter somewhat forwardly of the centre of the hull. In the first embodiment, the forward end 26 of each pontoon flows forward integrally to form a rim 27 for the peripheral edge of the bow, thereby providing the first embodiment with a smooth, curved, streamlined appearance from the bow to the rear ends 24 of the pontoons. The pontoons are buoyant to provide the boat with lateral and longitudinal stability and in the first embodiment are formed from a floatation material such as a foamed plastics material. In adaptations of the first embodiment, the pontoons may be hollow or even inflatable to provide the form described. As a large amount of buoyancy is positioned behind the engine, the boat will not tip over backwards and will not flood from waves approaching from behind.

The form of the pontoons is configured to be coordinated with the compound curve of the hull through the length of contact with the hull, as shown by cross-sections in Figures 11 and 12. This coordinated formation provides the hull with an extremely streamlined and efficient form throughout its length, which minimizes turbulence. Nevertheless, the pontoons provide the boat with very great lateral stability and also longitudinal stability because of their extension behind the stern of the hull. The channel between the hull and pontoons entrains air to create additional buoyancy and further reduce drag. The advantages of the hull arise due to three benefits of the form adopted for the hull, being a compound curve substantially conforming to an equiangular logarithmic curve, that curve preferably conforming to the Golden Section. The inventor has recognized that such forms provide a most advantageous structure. Firstly, that structures taking such a form have increased strength compared with other forms. Secondly, it is found that by providing the external surface of the hull with such a form, the turbulence caused as the boat traverses through the water is reduced. Thirdly, such structures facilitate the optimisation of the position of the centre of gravity.

The intention of the invention is to provide a boat structure which provides improved stress transfer by utilizing a structure that has full or partial adherence to equiangular, logarithmic form. In general, it has been found that the optimum characteristics are achieved for a particular structure where the equiangular logarithmic curve substantially conforms to the Golden Section. In addition, it has been found that, where a structure conforms to these characteristics of the invention, such a structure distributes load and is able to distribute an impact loading substantially uniformly thorough the structure in a manner better than that achieved by structures of alternative shapes. This is especially important for boats

■ when they impact waves or strike obstacles. The distribution of the load results in greater strength to weight or thickness ratios and greater impact strength than is achieved in alternative structures. In particular, as in the first embodiment, this strength is achieved without the need for an internal frame and without the need for excessive use of material. This reduces overall weight which in turn reduces the potentially destructive forces of impact.

The characteristics of the Golden Section are illustrated in Figure 13 which illustrates the unfolding of the spiral curve according to the Golden Section. As the spiral unfolds the order of growth of the radius of the curve which is measured at equiangular radii (eg E, F, G, H, I and J) is constant. This can be illustrated from the triangular representation of each radius between each sequence which corresponds to the formula of a:b = b:a+b which conforms to the Fibonacci ratio of approximately 1 :1.618 and which is consistent through out the curve.

It is a further preferred characteristic of the embodiments that not only do the X and Y axes conform to Golden Section geometry, but also the Z axis or depth of the member conforms, to the Golden Section in three dimensions.

Thus, the application of such shapes to a boat hull provides a means of optimizing the strength of the hull, without use of an internal frame but with minimum material usage and therefore weight. This strength of the boat can be enhanced if the foredeck 14 also is formed with a curvature conforming to an equiangular logarithmic spiral, preferably conforming to the Golden Section. In the embodiments this is done, thereby not only providing protection to the bow from water spray but also increasing the strength at the bow, the region requiring greatest impact strength. All this is achieved without the need of an internal frame, thereby reducing, weight and cost. Where point source load are to be experienced, such as at anchor rope tethers and mountings for engine and the like they are accommodated by providing rigidising or reinforcing materials within and enclosed by outer foam to thereby progressively distribute the loading into the hull.

In the first embodiment, the foredeck 14 is formed as a separate piece from the hull 12, for assembly after forming. This arrangement not only enables the hull to be manufactured more easily, but also allows a group of hulls to be stacked within each other for transportation, thereby substantially simplifying manufacture of the hull and reducing transportation costs. A group of foredecks can also be stacked together. Optionally, the windscreen 17 may be shipped independently from the foredeck for assembly at the delivery point. The foredeck 14 is secured to the hull 12 by one of a range of by one of a range of fixing means well known to those skilled in the art.

A second embodiment illustrates one adaptation of the boat of the first embodiment which includes the inventive features of the first embodiment. The second embodiment is described with reference to Figure 14. The second embodiment includes many features which are substantially the same as those of the first embodiment and therefore in the drawings, like numerals are used to depict like features. The drawings provided are directed to identifying features that differ from those of the first embodiment, and therefore not all views are shown.

As shown in the drawings, the second embodiment comprises a boat 111 having a hull 112. The boat 111 comprises a hull 112 having a hull floor 117 and a cowling covering the bow section 15 of the hull to provide a foredeck 14 in the same manner as the first embodiment. The chief difference between the second embodiment and the first embodiment is that, instead of being provided with pontoons 16, the hull 112 of the second embodiment is formed with pontoon-like formations 116 which are integral with the hull 112. Externally, the appearance of the hull 112 is almost identical to that of the first embodiment, but instead of having the inner wall of the pontoons extending within the cockpit area, these are removed. The hull floor is upturned at the sides to form the external wall of the pontoon-like formation 116. While there are no longer enclosed pontoons to provide floatation, the rear portion 132 of the pontoon formations 116 may be filled with floatation material as necessary. It can be seen that the second embodiment maintains all the inventive advantages of the first embodiment while providing additional space in the cockpit.

As mentioned above, the use of a hull having a configuration conforming to an equiangular logarithmic curve and preferably conforming to the Golden Section not only provides the vessel with increased strength, but also functions to provide an external surface which has a curvature which conforms to an equiangular logarithmic curve and preferably conforms to the Golden Section. It is found that such a surface is more effective at providing a streamlined form which reduces drag by decreasing turbulence. The embodiments serves to, in the greater part, enable water to move in its naturally preferred way. As the boat is propelled through the water, the water is disturbed to some degree. However, because the hull surface follows the form of an equiangular logarithmic curve, preferably conforming to the Golden Section, the water is caused to be displaced in a more natural manner because the surface of the hull acts upon the water in a manner to cause it to flow in its naturally preferred way. The inefficiencies created through turbulence and friction, and thus the drag, which are normally found in a boat hull are significantly reduced. Previously developed technologies have generally been less compliant with natural water flow tendencies. The means of attachment of the pontoons of the first embodiment to the sides of the hull to provide a continuously curved surface between the hull and the pontoons also facilitates efficient passage of the vessel through the water.

It can be seen that a boat constructed in accordance with the embodiments enables a hull to be provided that is lighter than is conventionally the case as well as having low drag. This will lead to a highly cost effective boat design when constructed from conventional materials such as wood, aluminium, fibreglass or polycarbonate.

Because of its light weight, a small propulsion plant provides exceptional performance at very low fuel consumption, yet the pontoons and optimized centre of gravity ensure high stability. Clearly, there are many aspects of the embodiments which may be modified while still maintaining the essential features of the invention. Such a lightweight craft could have a kite attached to it and operated in a way similar to kite surfing. The craft is stable so the operator can, if he so chooses, sit in it instead of standing. He can remain dry, i.e. does not have to fall into the water if the wind stops or he loses control of his kite. In this application, kite surfing can be an easier, safer, more comfortable and a more manageable sport. It is to be appreciated that all such adaptations and others not described are to be considered as being within the scope of the invention.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

I claim:

1. A hull of a water craft adapted to float on a body of water for traversal thereof, the hull having an external surface which in use contacts the body of water, wherein at least a substantial portion of the external surface has a curvature wherein the curvature substantially conforms to a logarithmic curve.

2. A hull claimed at Claim 1 wherein the radius of the logarithmic curve unfolds at a constant order of growth when measured at equiangular radii, that is, that the curvature conforms to the Golden Section.

3. A hull of a water craft adapted to float on a body of water for traversal thereof, at least a substantial portion of the hull being formed from material of substantially uniform thickness wherein the material has curvature which conforms to a logarithmic curve.

4. A hu|l as claimed at claim 3 wherein the radius of the logarithmic curve unfolds at a constant order of growth when measured at equiangular radii, that is, that the curvature conforms to the Golden Section.

5. A hull as claimed at claim 3 or 4 wherein the hull is formed without a frame for stiffening and/or strengthening the hull.

6. A water craft comprising a hull as claimed in claim 1 or claim 3.

7. A water craft as claimed in claim 6 wherein the boat is provided with stabilizing pontoons associated with the sides of the hull.

8. A water craft as claimed in claim 7 wherein the pontoons are buoyant.

9. A water craft as claimed in claim 8 wherein the pontoons are formed from floatation material.

10. A water craft as claimed in claim 9 wherein pontoons are formed from a foamed thermoplastics material.

11. A water craft as claimed in claim 7 wherein the pontoons are inflatable.

12. A water craft as claimed in claim 7 wherein the pontoons are hollow.

13. A water craft as claimed in claim 7 wherein the pontoons take a streamlined shape.

14. A water craft as claimed in claim 7 wherein the rear of the pontoons extend beyond the stern of the hull.

15. A water craft as claimed in claim 7 wherein the pontoons take a bulbous form extending longitudinally from a reduced cross-section or apex at the rear to an enlarged lateral cross-sectional profile proximate the stern of the hull, and thereafter reducing in lateral cross-section to a position intermediate the stern and the bow of the hull.

16. A water craft as claimed in claim 15 wherein external outline of the longitudinal cross-sectional profile of the pontoons is curved, .

17. A water craft as claimed in claim 15 wherein the forward end of the pontoon extends into a formation providing a rim for the bow of the hull.

18. A water craft as claimed in claim 7 wherein the pontoons are engaged with the sides of the hull in a manner to provide a continuously curved surface between the external surface of the hull and the external surfaces of the pontoons.

19. A water craft as claimed in claim 1 or claim 4 wherein the water craft is provided with a cowling overlying the bow section of the hull, a substantial portion of the cowling taking the form of a compound curvature which conforms to a logarithmic curve.

20. A water craft as claimed in claim 19 wherein, the curvature of the cowling conforms to the Golden Section.

21. A water craft as claimed in claim 6 wherein the hull is provided with stabilizing pontoon-like formations integrally formed with the sides of the hull.