This invention relates to folding boats.

Folding dinghies and boats are well known craft which have been produced in order to enable a small boat to be reduced in size so that it can be more easily stored when not in use.

Most examples are constructed of flat panels which are then stressed by being bent and members are introduced to hold the stressed panels in position. Other examples use fabric and wood separating pieces which again hold the shape of the boat.

Current practice, however, produces folding boats that use heavy materials, making them awkward to carry, are rather flimsy when ready for use and usually have separate pieces that need introducing to hold the unfolded boat in shape. They are often at odds with the conventional idea of the look of a seaworthy craft.

According to the present invention, a specific geometry is used to enable all the parts needed to complete the craft to be permanently fixed to the assembly and that this assembly is built around a strong central spine from which the parts unfold. The assembly is constructed in lightweight materials that make it easy to carry and are relatively maintenance free. The shape of the boat when assembled is consistent with universally accepted ideas of what a seaworthy craft should be like.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 shows a longitudinal section through the centre line of the boat.

Figure 2 shows the plan view of the boat.

Figure 3 is a transverse section through the boat showing the boat folded.

Figure 4 is a transverse section showing the boat unfolded.

Figure 5 is a perspective view of the boat folded.

Figure 6 is a perspective view of the boat unfolded.

Referring to the drawings, the boat comprises a central spine made up of a keelband 1 constructed, for example, in a glassfibre and foam sandwich to which vertical members, the transom knee 2, the centreboard case 3 and the mast support 4 are connected. The top of these members are connected together and to the keelband by a tie member 5 made, for example, of aluminium tube. Other vertical members may be added or these omitted and the tie member only attached between the two ends of the keelband.

Stringers 6 made from aluminium tube and gunwale members 7 made in glassfibre are pivoted at the two ends of the spine on for example pins 8, arranged in such a manner that the stringers can lie side by side in the folded situation and be able to pivot outwards in the direction of arrow 9. Fabric 10 is connected to the keelband and to the gunwale members and stringers. The fabric is tensioned over the stringers when they are pivoted outwards and upwards.

Rib formers 11 which preferably are hollow and form seats and provide buoyancy, are attached to the vertical members on the spine by, for example hinges, which allow the rib formers to be pivoted outward in the direction of arrow 12 and to locate with the stringers and the gunwale members and lock the whole assembly in position.

The basis of the geometry is that the shape of stringers and gunwale members must approximate to the shape of the keelband profile so that the stringers and gunwale members can fold inside the keelband.

Stiffening members 13 can preferably be attached to the fabric near the keelband so as to provide a more rigid floor on which to stand.

A mast and sail can be secured into the mast support tube and a rudder and centreplate fitted and the boat can be converted for sailing.

A further embodiment is described by reference to the accompanying drawings in which: -

Figure 7 is a transverse section through the boat.

Figure 8 is a more detailed transverse section.

This embodiment enables an extremely rigid boat to be constructed without the use of fabric.

Referring to the drawings, the boat consists of a hollow central spine

14 on which rigid stringers 15 are pivoted as before described. In this embodiment the stringers are wide interlocking plates which also form the skin of the boat. The interlocking of the plates is achieved by shaping the edges of the plates or by adding, for example, aluminium extrusions specially designed to interlock accurately. A watertight joint can be achieved, for example by the introduction of a neoprene gasket

16. The rib formers 17 pivoted on the central spine as previousl described are designed to press the interlocking joints together at th same time as retaining the whole assembly in position as before.

In this embodiment it is more critical to position the pivot points fo the stringers and gunwale members correctly, so that they stack whe folded and properly interlock when unfolded.

Yet another embodiment is described with reference to Figures 9 t 13, of which:

Figure 9 is a perspective view of the boat in use;

Figure 10 is a side elevation corresponding to Figure 9; and

Figures 11 to 13 are sectional views of the boat showing successive stages from the fully collapsed position shown in Figure 11 to the fully extended configuration shown in Figure 13.

The boat comprises a keelband 90, for example formed as hereinbefore described with reference to Figure 1, extending from the transom 91 forward to a curved bow portion 92. Extending upwardly from the keelband 90 are a transom knee 93, a centreboard case 94 and mast support 95, and hinged on each side of each of these are rib formers 96 each in the form of a shaped frame and each pair carrying a seat 97.

Longitudinal stringers 98 are hingedly connected to the transom and the bow section of the keelband and a waterproof fabric 99 is extending over the stringers 98 when in their fanned out configuration as shown in Figure 13. A tubular gunwale member 100 extends along the uppermost stringer 98.

Figures 11 to 13 illustrate the stages in assembly of the boat from its folded configuration as shown in Figure 11. The first stage is to inflate the tubular gunwale members 100, as shown in Figure 12. The fabric 99 and the stringers 98 are then fanned outwardly and upwardly with the gunwale members 100 so as to stretch out the fabric. When the general configuration shown in Figure 13 is achieved, the rib formers 96 are then hinged outwardly to engage the stringers 98 and thereby lock the whole structure into its open position. The seats 97 are then positioned on top of the rib formers 96 and hinged floor panels 101 are swung outwardly and downwardly from the keelband 90, the floor members having shaped ends to clip on to the lower of the stringers 98, thus locking them in position.

The gunwale members 100 may be provided with fittings conventional for an inflatable boat. This embodiment of the invention provides the convenience of packing for an inflatable boat, with the rigidity and strength of a conventional boat.