HULL FOR A WATER CRAFT

Abstract

The present invention relates to a hull for a water craft. More particularly it relates to an inflatable hull with flexible tension members acting in tension, and extending between the gunnels to aid in maintaining the hull shape in operation.

Claims

1. A hull for a water craft, the hull comprising; a. an inflatable body comprising two flanks configured to be inflated, each flank forming port and starboard sides meeting together to form a vee shaped hull; the flanks when inflated extending away from each other to terminate at gunnels; and b. at least one flexible member extending directly between the gunnels, the flexible member being in tension in a beam direction between the gunnels when the body is inflated.

2. The hull as claimed in claim 1, wherein the flexible member is of a size so as to be in tension when the body is inflated.

3. The hull as claimed in claim 1, wherein the flexible member is a strap, cable or planar sheet.

4. The hull as claimed in claim 1, wherein the flexible member cannot act in compression between the port and starboard sides.

5. The hull as claimed in claim 3, wherein the flexible member is a strap.

6. The hull as claimed in claim 5, wherein there are multiple straps spaced apart along the length of the body.

7. The hull as claimed in claim 1, wherein there is an inflatable tube along the length of the gunnels.

8. The hull as claimed in claim 1, wherein the body is relatively stiff when inflated.

9. The hull as claimed in claim 1, wherein the two flanks meet together to form a, or part of a, keel.

10. The hull as claimed in claim 9, wherein the flanks form a depth between the uppers surfaces and where the flanks meet.

11. The hull as claimed in claim 10, wherein the straps extend over the depth.

12. The hull as claimed in claim 1, wherein the hull comprises rigid floor boards configured to be laid upon the straps, when the body is inflated.

13. The hull as claimed in claim 12, wherein the rigid flow boards act in compression, when the straps act in tension.

14. The hull as claimed in claim 13, wherein the straps indirectly compress the floor boards.

15. The hull as claimed in claim 9, wherein the distance between gunnels with the straps in tension is less than the distance between gunnels without the straps.

16. The hull as claimed in claim 9, wherein the straps extend between the port and starboard sides to pull in the flanks of the vee shaped body towards each other.

17. The hull as claimed in claim 9, wherein the vee shaped body flanks are always pushing outwards, or resisting the force of the strap.

18. The hull as claimed in claim 1, wherein the hull is configured to plane.

19. The hull as claimed in claim 1, wherein tension in the flexible member is increased as vertical load on the body and/or keel increases during operation.

20. A water craft comprising the hull as claimed in claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0079] The invention will now be described by way of example only and with reference to the drawings in which:

[0080] FIG. 1: shows a top perspective view of a hull of the present invention.

[0081] FIG. 2A: shows a cross section through the longitudinal length view of a hull of the present invention.

[0082] FIG. 2B: shows the forces apparent in a schematic view of a cross section through the longitudinal length of a hull.

[0083] FIG. 3: shows a side schematic view of a hull.

[0084] FIG. 4: shows a cross sectional view of a hull strapped and unstrapped (shown in dashed lines).

[0085] FIG. 5: shows a cross sectional view of a hull with floor panels and tubes attached.

[0086] FIG. 6: shows a top perspective view of a hull with wider flexible members.

[0087] FIG. 7: shows a top perspective view of a hull with cables as flexible members.

[0088] FIG. 8: shows a top perspective view of a hull with tubes attached, and a cut away view of the floorboard showing the flexible members.

[0089] FIG. 9A: shows a schematic cross section view of a dual layer drop stitch material to be used for the hull body.

[0090] FIG. 9B: shows a schematic cross section view of a dual layer material to be used for the hull body.

[0091] FIG. 9C: shows a schematic cross section view of a dual layer material to be used for the hull body.

[0092] FIG. 10: shows a top perspective view of a hull with flexible members extending between the flanks.

[0093] FIG. 11: shows a top perspective view of a hull with a round bottom.

[0094] FIG. 12A: shows a top perspective view of a hull with support members.

[0095] FIG. 12B: shows a top perspective close up view of support members.

[0096] FIG. 12C: shows a side view of a hull with support members.

DETAILED DESCRIPTION

[0097] With reference to the above drawings, in which similar features are generally indicated by similar numerals, a hull according to a first aspect of the invention is generally indicated by the numeral 1 and as shown in FIG. 1. The hull 1 is to be used in a watercraft 100, as shown in FIG. 8 The hull of the present invention has two main components comprising a body 2 and one or more flexible members 3. The body 2 forms a Vee shaped hull as known in the art. Preferably the vee body is configured and shaped to plane on water. The body 2 is inflatable so as to be able to be deflated and packed down into a transportable state. An inflation and deflation point 14 will be located on the hull body 2, one location is shown in FIG. 1. In the inflated condition, the body 2 is relatively stiff so as to form the shape of a Vee. The body 2 has the typical features of a hull, such as; flanks 4, gunnels 6 at the upper periphery of each flank 4, a keel 5 intermediate the two flanks 4, a bow 7, a stern 8, a stem 9, and a transom 10. In a deflated condition, the hull body 2 is able to be collapsed/deflated to be packed into a smaller footprint and/or volume. The deflated condition can be used for storage and/or transit.

[0098] In one embodiment the body 2 also comprises a one or more tubes 11 that run around the gunnels or upper periphery of the body 2 as shown in FIG. 5. The tubes can be inflated to form an inflatable tubed boat as known in the art, and deflated like the hull body 2.

[0099] The hull 1 of the present invention also comprises one or more flexible members 3 that extend between the gunnels 6 on either flank 4 of the body 2, to act as thwarts in tension only (not in compression). The one or more flexible members 3 are configured to in operation, i.e. the body as inflated, be in tension as shown in FIGS. 2A and 2B. The flexible members 3 are able to collapse, and pack down, when the body 2 is deflated. The flexible members 3 do not prohibit collapse/deflation of the body 2, nor packing down or away.

[0100] Preferably the flexible members 3 are in tension during attachment. The flexible members 3 having a length between the gunnels 6 less than the inflated beam width of the body 2 without the flexible members 3 attached, as shown in FIG. 4. As such, when the body 2 is inflated to its rigid or semi-rigid condition, the one or more flexible members 3 can deform the body 2 gunnels 6 towards each other so they are not able to separate as much as their unconstrained inflated configuration.

[0101] In an alternative embodiment, the body 2 is not deformed in from the gunnels, instead the one or more flexible members 3 are elasticated so as to always be in tension. However it likely that there will always be a degree of give in the hull body 2, so the gunnels 6 always draw together a little. There may be many ways in the art a skilled person is able to provide the one or more flexible members 3 to be in tension.

[0102] The purpose of the one or more flexible members 3 is to provide rigidity to the body 2. Typical boats of this nature often have a rigid hull, i.e. a rigid inflatable boat (RIB). These boats often have an inflatable tube as seen in the present invention, however their body or hull is rigid not inflatable. This is because the prior art technology is not able to provide a rigid enough hull that is both a vee shape and inflatable. The current invention has a vee shaped inflatable hull, which is typically only possible with a few known inflatable hullsyet more rigidity is desired. To provide a more rigid inflatable vee shaped hull, the one or more flexible members 3 are used to draw the hull into a strained condition, increase it resistance to spreading between the gunnels 6, and/or increase its torsional strength.

[0103] The flanks 4 of the body 2 are suitably stiff so when inflated they resist crumpling, buckling or substantial bowing. During operational loads, such as the hull 1 travelling through a body of water, normal force loads X onto the keel 5 push the keel 5 upwards towards the flexible members 3 as shown in FIG. 2B. This upwards force X wants to displace the keel 5 vertically towards the gunnel 6. This displacement wants to spread the gunnels 6 apart from one another, i.e. to open up the Vee. The one or more flexible members 3 resist this spreading apart of the gunnels 6 by acting in the tension in the tension direction Z. The spreading apart of the gunnels 6, is a particular feature of the shape of the hull 1.

[0104] The vee shape of the hull allows the water craft 100 to plane in operation. The planing of the watercraft 100 means that the majority of the displacement pressure (from the water) on the hull 1 is located at or towards the keel 5. This displacement pressure on the keel 5 has the effect of pushing apart the gunnels 6 from each other. Whereas displacement hulls have a water line towards the gunnels or towards the outer chines. This displacement pressure of the water wants to force the gunnels 6 towards each other

[0105] In a preferred embodiment the flexible members 3 are straps 3. There can be one or more straps 3 along the longitudinal length (aft to bow) of the hull 1. In one embodiment for example, on a hull less than 4 metres there are between three and four straps 3. In one embodiment for example, the straps are 150 mm wide. However it is envisioned that a person skilled in the art will realise that the straps can depend on the characteristics of stiffness required or operational tension present, taking into account hull size, shape and material characteristics of the flexible members 3.

[0106] A skilled person in the art will realise that any substantially flexible material may be used to provide tension between the gunnels 6. The two requirements for the flexible members 3 are that they; are flexible, i.e. can be packed down for deflation of the hull 1; and the second requirement is that they are able to withstand tension between the gunnels 6, i.e. they are not significantly stretchable.

[0107] As such other flexible member 3, other such configurations such as cables 3A may also be used instead of, or in combination with, straps 3. The cables 3A may extend directly across the beam between gunnels 6. Alternatively, the cables may be laid diagonally between the gunnels 6. The cables may be criss-crossed along the length of the body 2. The cables 3A may be formed of a number of materials, such as fibreglass, carbon fibre, fabric, plastic, or metal. In other embodiments, instead of cables or straps the flexible members 3 may be a planar sheet. The sheet may cover the entire top surface between the starboard and port gunnels 6. The sheet is then able to take tension between the starboard and port gunnels 6. A further embodiment is shown in FIG. 10 where flexible members 3 are affixed to, or integral with, the flanks 4 of the hull body 2. The flexible members 3 may be located at numerous positions on the flanks. However the flexible members 3 offer the most degree of hull rigidity when attached to the gunnels 6.

[0108] The applicant has found that using straps 3 less than 200 mm wide appears to be optimum for a length of boat less than 4 metres.

[0109] Preferably the hull body is formed between a dual layer material. We had the area intermediate the 2 layers may have a compressed gas within it. Some examples of a dual layer material are a drop stitch material. The layers themselves may comprise a synthetic elastomersuch as chlorosulfonated polyethylene (CSPE) synthetic rubber (CSM)also known as HYPALON, polyurethane or PVC. Suitably stiff inflatable materials are known in the art for inflatable boats and stand-up paddle boards. A dual layer material is shown in FIG. 9A however other substantially stiff yet inflatable materials are shown in 9B & 9C. Where FIG. 9B shows an inflatable tube type system that extends between an inner surface 2A and an outer surface 2C. Wherein the inner material 2B is column. FIG. 9C shows a foam type material 2B intermediate the inner surface 2A and the outer surface 2C. FIG. 9A shows a HYPALON material 2A and inner surface 2A and outer surface 2C with the drop stitch material 2B interspersed there between.

[0110] The hull body 2, in particular the flanks 4, needs to be substantially stiff to transmit the loads upwards from the keel 5 or flanks 4 to the gunnels 6 without substantial bowing, crumpling or buckling of the flanks 4. The keel 5 may be stiffened further by a stiffening member 13 as shown in FIG. 2A.

[0111] Supporting members 20 may be used intermediate the straps 3 and the upwards facing surfaces of the flanks 4 and/or keel. The supporting members 20 may be adhered to straps 3 by Velcro, adhesive means, sit snuggle in-between, or by other engagement means suitable. The supporting members 20 may be stitched or non-removably attached to the straps 3. Preferably the supporting members 20 are composed of EVA foam or other suitably rigid material. Ideally the supporting members 20 are able to be easily removed from the hull, so the they can be packed/compressed down into a transportable state.

[0112] The purpose of the supporting members 20 is to add additional resistance for the keel to prevent it from being pushed up, or from collapsing or bucking upwards towards the straps. The support members 20 act as spacers intermediate the straps 3 and the top surface of the keel. Preferably the support members are rigid enough to keep the spacing intermediate the straps 3 and the top surface of the keel, but are still able to be compressed so it they can be packed down into a transportable state, along with hull.

[0113] The support members may assist in the hull having rigid hull performance, but still be able to be packed down into a transportable state. Support members 20 may only be required in some boat configurations, where particularly large loads are induced on the hull. For example; with heavy or numerous crew, heavy sea conditions, and/or with higher horsepower engines.

[0114] In alternative embodiments the support members are inflatable. There may be one or more support members 20, i.e. under all straps, or under one or more straps. The support members 20 may be a number of different of shapes, and located at different areas between the flanks and straps, but preferably they are located between the keel (meeting point of the flanks) and straps.

[0115] In one embodiment, the EVA foam of the supporting members 20 can be any density, for example between 28 kg/m3 to 420 kg/m3. As long as the foam is able to compressed down into a compact form, and is able to support the straps. The higher density foams will support higher loadings however, i.e. rougher seas, faster planing etc.

[0116] In one embodiment, a 3.8 m boat, can be packed down in to a 1 m0.5 m0.5 m box, i.e. 0.5 of a cubic metre.

[0117] Any grade of foam hardness will likely be sufficient for hull stability, some example hardness characteristics are between 10 and 90 Asker C.

[0118] Floorboards 12 may be laid upon the straps 3, or gunnels, in between the starboard and port gunnels 6. Preferably the floorboards 12 lie intermediate the gunnels 6 and the tubes 11. In one embodiment, the tension of the straps 3 intermediate between the starboard gunnel 6 and port gunnel 6 puts the rigid floorboards 12 into compression. This is achieved by having the floorboards 12 wedged in between the gunnels 5 or tubes 11, or other like member at or towards each opposing gunnel 6, and the flexible members 3 drawing in opposing gunnels 6 towards each other so as to simultaneously squeeze the opposing edges of the floorboards together. The combination of the floorboards 12 in compression, and the straps 3 in tension, provide a substantially stiff upper assembly that will add rigidity and torsional strength to the hull 1. The floorboards 12 are as known in the art, for example in rigid inflatable boats. The floorboards may be one piece, or more preferably may be two or three pieces that can be laid inwards and easily removed during deflation of the hull 1.

[0119] As discussed previously preferably the inner surface 2A and outer surface 2C are of a HYPALON material. However other materials are envisaged by a person skilled in the art. The straps 3 or flexible members 3 may be integral or attached with the inner surface 2A or outer surface 2C. In one embodiment the straps 3 are integral with the outer surface 2C such that the straps extend around the perimeter, through an elongate cross section, of the hull body 2. However in a preferred embodiment, the straps 3 are separate straps that are attached to the hull body 2. In a preferred embodiment the ends of the straps are glued and/or mechanically attached to the gunnels 6. Preferably the straps extend over the gunnel and also the outwale 16. The straps are preferably glued and/or stitched to the hull body 2.

[0120] In a preferred embodiment the straps 3 comprise a HYPALON material. The straps 3 are preferably thin, fabric like, and not inflatable or stiff. The straps may be composed of numerous materials as known in the art that are not significantly stretchy, and are able to withstand tension, be flexible, and be durable and long lasting in a marine environment.

[0121] Where a vee shaped hull is mentioned and described, a similar concave shaped hull may also suffice. For example a U shaped hull (FIG. 11 shows an example of a round bottom/U shaped hull), double ended hull, deep or shallow or changing deadrise, multiple chine, hard or soft chine, etc. As long as the flanks, between the keel 5 (described herein as the bottom most part of the hull body 2, running between the bow and stern) and the gunnels 6, are suitably stiff to prevent buckling, and the flexible members 3 can extend across and above a portion of the hull body to draw the flanks 4 into each other to enhance rigidity, and prevent spreading of the gunnels 6 i.e. shallowing of the hull body 2. Furthermore, the hull is preferably a planing hull so the displacement forces are located at or towards the keel 5 and not towards the gunnels 6. Where a round bottom or similar hull is described, or used, it is assumed it can be separated into two flanks 4, which are defined as being port and starboard of the hull body 2 midline, even though the flanks 4 are not well defined. The flanks may be integral with each other, or formed from different sections. Preferably the body 2, is one inflatable section.

[0122] Preferably the flexible members 3 are not deflected between their attachment points (at the gunnels or flanks). I.e. the flexible members 3 run straight, or uninterfered/unhindered, between their attachment points 15/meeting points 15 with the body 2 on each flank 4.

[0123] Where gunnels 6 have been described, the gunnels 6 are in relation to location for the hull body, i.e. at the port and starboard upper and outermost edges of the flanks 4 of the body 2. Further additions to the hull, such as tubes located at a portion of the perimeter, may also be defined as gunnels in nautical terminology, but not in this specification.

[0124] Where in the foregoing description reference has been made to elements or integers having known equivalents, then such equivalents are included as if they were individually set forth.

[0125] Although the invention has been described by way of example and with reference to particular embodiments, it is to be understood that modifications and/or improvements may be made without departing from the scope or spirit of the invention.