AQUATIC CRAFT

Abstract: An aquatic craft comprises a boat hull (1) having longitudinally extending buoyancy chambers (8) integrally formed with the walls (3) of the boat hull to provide rigidity in construction and buoyancy in the event of a capsize. The floor (2) of the boat hull (1) is substantially flat or planar and ideally respective side portions of the hull floor slope upwardly and outwardly from a central keel at 7.5 degrees to a horizontal datum. The hull may also include a stabilising keel member (28) comprising a pair of substantially planar wing members (30) extending laterally from a downwardly depending support member (29).

Description: "AQUATIC CRAFT" THIS INVENTION is concerned with improvements in or relating to aquatic craft and in particular to a craft having integral bouyancy means. Most small dinghies and the like, whether manufactured from aluminium fibreglass or timber, have outwardly sloping sides and upwardly sloping floors on either side of the keel to provide a compromise between internal space for passengers and stability whilst in motion. While traditionally designed craft are reasonably safe in the hands of skilled operators they can be quite unsafe in the hands of unskilled persons. For example the cross-sectional shape of a traditionally designed craft approximates very loosely to a semi-circular shape. The seating of such craft conventionally extends athwartships and thus when a person sits immediately beside the gunwale of the craft, part of his weight is cantilevered over the region of the chine thus markedly reducing stability of the craft. Many small boat accidents have been attributed to capsizing where the weight of persons and other load being carried is poorly distributed. Generally speaking, with conventionally designed small craft the load being carried must be distributed along the central axis over the keel or distributed equally on either side thereof for maximum stability. In an endeavour to reduce costs, aluminium dinghies are being made from lighter gauge sheet. This usually necessitates the formation of longitundinal ribs pressed into the sheet to stiffen the hull. Built-in seats or thwarts are essential to the opposing gunwales together. Such craft are however prone to torsional deformation along a longitudinal axis. Another difficulty associated with small craft of the type generally referred to above is that there is insufficient space available within the hull to accomodate enough bouyancy for the weight of the craft and its load. If any bouyancy is provided it is usually in the form of foam filled or watertight compartments under the athwartships seating. In marked contrast to small boat hulls of traditional design inflatable craft provide excellent stability with a relatively flat hull floor and longitudinally extending bouyancy chambers down each side of the hull. Inflatable craft combine maximum stability with maximum space within the hull and at the same time permit shallow draught operation not otherwise possible with conventional dinghy hulls. Inflatable craft however do suffer a major disadvantage in that they are expensive to purchase and lack durability. The combined effects of weathering and abrasion severely limit the useful life of inflatable craft compared with traditional materials. A further disadvantage of inflatable craft is a phenomenon known as "porpoising" wherein the bow of the craft rises and falls quite alarmingly at relatively low speeds. "Porpoising" is caused by a combination of factors including low hull weight, a relatively flat bottom and the absence of a sharp vertical bow section. It is an aim of the present invention to provide a small craft which overcomes or alleviates the problems of prior art small craft. According to the invention there is provided a boat hull including bouyancy means associated with opposed side walls of said hull said bouyancy means being formed integrally with and extending longitudinally of said side walls, said side walls comprising watertight walled compartments. If required the compartments may be filled or partially filled with a cellular plastics foam material. Preferably the side walls of the hull are parallel to each other. The floor of the hull may be flat or slope downwardly from the outer side walls to a central keel portion. Preferably the floor includes side portions which slope at an angle of between two and a half degrees and thirty degrees relative to a horizontal datum, more preferably between five degrees and fifteen degrees, but most preferably at seven and a half degrees. The bow portion of the hull includes an upwardly directed taper from the hull floor and preferably includes an inwardly directed taper from the side walls of the hull. Suitably the bow portion is formed integrally with the hull floor and side walls. A preferred embodiment of the invention will now be described with reference to the accompanying drawings. Although the preferred embodiment is described with reference to a boat hull fabricated from aluminium sheet, it is to be understood that the invention may be made from any other suitable material such as sheet metal, sheet plastics material or moulded from glass fibre reinforced plastics resin or combinations thereof. In the drawings FIG 1 shows a plan view of a boat hull FIG 2 shows a rear elevation FIG 2a shows an enlarged view of part of FIG 2 FIG 3 shows a side elevation of a bow portion FIG 4 shows a plan view of a keel FIG 5 shows a front elevation of a keel In Fig 1 the boat hull 1 comprises a floor 2, side walls 3, a transom 4 and a bow portion 5. Carry handles 6 may be provided at any convenient location such as on the transom 4 and forward side walls 3 as shown. A mooring cleat 7 may also be provided. FIG 2 shows a rear elevation of the hull of FIG 1 from which it can be seen that side walls 3 comprise a closed chamber 8 bounded by an outer wall 9 a curved upper wall 10 and an inner wall 11. The chambers 8 extend along each side of the hull and if required may extend partially into the bow portion as shown in phantom at 12. Cavities 13 may be formed in inner side walls 11 for storage or the like. The chambers 8 are constructed so as to be watertight and if required may contain cellular plastics foam such .as a closed cell rigid polyurethane foam. A false internal floor or duckboards 14 may be provided for comfort and drain plugs 15 are fitted to the transom 4. For larger boats a frame of longitudinal and transverse members may be provided between the bottom skin of the hull and the floor to provide reinforcing against deformation. The boat hull is suitably manufactured from sheet aluminium welded at the joins. The floor 2 may be made from a single rectangular sheet of aluminium creased or folded to form a keel 16. Preferably however the floor is formed from two sheets 17, 18 as shown in FIG 1. The sheets 17, 18 are cut along the lines 19, 20 as shown in phantom to form part of the bow section. Side walls 3 are formed by shaping sheets of aluminium by rolling or the like into a channel section having a cross section in the form of an inverted "U" as shown in FIG 2. The hull floors 2 are joined at the keel by welding the edges in an appropriately shaped aluminium extrusion 21 (shown enlarged in FIG 2a) having receiving slots 21a for the edges of the aluminium sheets and a perpendicular stiffening flange 21b. The floors 2 are elevated at their outer edges to form angles of seven and a half degrees to the horizontal. The outer edge portions 22 of floors 2 are joined to the free edges of outer walls 9 by a joining extrusion 23 having a configuration similar to that of keel extrusion 21.. This provides an outwardly extending flange 23a which acts as a strake operative to provide stability in high speed turning manouvres and to reduce spray. The free edges 24 of inner wails 11 are welded to the inner surface of floors 2. An appropriately shaped transom 4 is then welded to the rear end of the hull. FIG 3 illustrates the bow section. As shown in FIG 1 the front or bow portions of sheets 17, 18 are cut to a predetermined shape. The pointed ends 25 are brought together by bending the bow portions upwardly and adjoining edges 20 are welded together. The bow is completed by welding in fillets 26 and a preshaped foredeck 27 with a transverse bulkhead 27a to form a watertight forward compartment. The upward taper of the bow may be modified in either or both of the longitudinal and transverse axes by appropriate shaping of edges 19 and 20. The completed craft is an extremely rigid construction owing to the longitudinally extending boxed side walls 3. This rigid construction prevents twisting and bending commonly found in both conventional small craft and in inflatable dinghies. It will be readily apparent that the invention enables the combination of conventional boat building techniques with the advantages of the design features of an inflatable craft but without the disadvantages of either conventional or inflatable craft. To assist in the stability of the craft whilst in motion, a small keel fitting 28 may be attached to the keel as shown in FIG 3. The keel fitting 28 comprises a downwardly depending portion 29 and transversely extending portions 30 shown in FIG 4. FIG 5 represents an enlarged front elevation of the view of the fitting 28 shown in FIG 3. Transversely extending portions 30 are inclined downwardly towards their outer extremities. The keel fitting 28 serves a dual function. Downwardly depending portion 29 serves to provide lateral stability to the craft for steering either in straight lines or during turns. The transverse portions 30 serve to provide a substantial degree of control over "porpoising", particularly in choppy or rough waters. The craft according to the invention is extremely stable and is considered to be unsinkable. The configuration of the craft enables the curved upper portions 10 of side walls 3 to be used safely as seats without the risk of capsizing and the inherent stability conferred by the relatively flat bottom and keel fitting 28 make the craft suitable for a wide variety of purposes for use by skilled and unskilled operators alike. It is not considered necessary to provide athwartships seating but if required one or more seats 31 could be provided. The flotation characteristics of the craft enable it to be self draining even when completely swamped with water. In addition there is not the tendency as with conventional craft to capsize when swamped with water. The very low draught and large flotation compartments enable the craft to be used without a transom or at least a substantial portion thereof. In this manner self draining would be virtually instantaneous in the event of swamping but to prevent the ingress of a stern wave a hinged or shuttered transom door could be fitted. The craft is suitable for propulsion by any suitable means such as oars, an outboard or inboard motor or even sails. The large uncluttered internal space makes the craft very suitable for use as a work boat for fishermen, divers, scientists etc. It will be readily apparent to a skilled addressee that many modifications and variations are possible with the invention without departing from the spirit and scope thereof.

Claims: - CLAIMS 1. A boat hull including bouyancy means associated with opposed side walls of said hull, said bouyancy means being formed integrally with and extending longitudinally of said side walls, said side walls comprising watertight walled compartments. 2. A boat hull as claimed in claim 1 wherein said watertight walled compartments are at least partially filled with a cellular plastics material. 3. A boat hull as claimed in claim 1 or claim 2 wherein a floor of the hull is substantially planar. 4. A boat hull as claimed in claim 1 or claim 2 wherein the hull floor includes side portions extending from each side of a longitudinally extending keel member to respective side walls of said hull, said side portions sloping upwardly away from said keel portion at an angle between 2.5 degrees and 30 degrees. 5. A boat hull as claimed in claim 4 wherein said side portions slope at an angle of between five degrees and 15 degrees. 6. A boat hull as claimed in claim 5 wherein said side portions slope at an angle of 7.5 degrees. 7. A boat hull as claimed in claim 6 wherein said bow portion is formed as a watertight compartment. 8. A boat hull as claimed in claim 2 wherein said watertight walled compartments include a convexly curved surface extending longitudinally of said hull. 9. A boat hull as claimed in claim 8 wherein said watertight walled compartments include one or more recessed compartments having an opening in an inner wall of one or more said compartments. 10. A boat hull as claimed in claim 1 including a stabilizing member associated with a keel member, said stabilizing member .comprising a support member depending downwardly from said keel member and laterally extending wing members spaced from the outer surface of said boat hull_. 11. A boat hull as claimed in claim 10 wherein said wing members slope downwardly and outwardly from said support member. 12. A boat hull as claimed in claim 11 wherein said stabilizing member is associated with said keel member adjacent a junction between a curved bow portion of said keel and a linear hull portion of said keel.

Inventors: CLARK KENNETH GEORGE, CLARK, KENNETH, GEORGE
Applicants: CRAFTEX PTY LTD, CRAFTEX PTY. LTD.
Application year: 1986
Main classification: B63B43
IPC codes: B63B43