EP0013114B1

EP0013114B1 - Inflatable boat

Info

Publication number: EP0013114B1
Application number: EP79302932A
Authority: EP
Inventors: Richard John Arthur Harding
Original assignee: Avon Inflatables Ltd
Current assignee: Avon Inflatables Ltd
Priority date: 1978-12-29
Filing date: 1979-12-17
Publication date: 1983-07-20
Also published as: NO150553C; DE2965967D1; EP0013114A1; CA1116477A; NO150553B; NO794213L

Description

This invention relates to an inflatable boat with a flexible skin defining the bottom of said boat; a reaction member having a rigid reaction surface overlying said skin; and inflatable members between said bottom and said reaction surface, each inflatable member when inflated deforming said skin into a keel.
Such a boat is known from the document DE-A-1964657, from which the present invention is distinguished, shows a boat with multiple keels formed by inflatable members. They are arranged so that the boat rises when at speed. They are orientated in such a way to tend to direct water flow towards the motor at the rear of the boat.
There have been other prior proposals relating to the underwater surface of inflatable boats, and it has also be suggested that for rigid-hull boats multi-keel underwater surfaces should be provided. Thus in GB-A-1,273,692 there is disclosed a boat hull provided in a forward section with a twin keel and in a rearward section with a single keel. The forward twin keels may each be lowerable or raisable to improve riding characteristics of the hull.
In GB-A-1,319,072 there is disclosed an inflatable boat in which the shape of the hull is a function of the hull construction itself of a number of infalatable tubes which cooperate to provide a generally U-shaped or V-shaped cross-section for the hull.
In GB-A-1,362,677 here is disclosed an inflatable boat having inflatable side walls serving as floatation members, a flexible underwater skin, a rigid deck and between said skin and deck an inflatable former member along the longitudinal centre-line of the boat shaping the flexible skin to form a central keel.
In none of these prior art proposals has it been appreciated or suggested that by having a boat with a flexible underwater skin and inflatable former members to cause the undersea surface of the boat to have a multi-keel construction, automatic adaptation of the planing characteristics of the boat to the load carried in the boat could be achieved.
The present invention overcomes these disadvantages by providing a boat having a keel on each side of the centre line of the boat with a constant-width channel between the mutually parallel keels centered on the centre line, the channel formed by said skin being continuous and water-contacting when the members are inflated and the boat is at rest, the channel also being continuous along the parallel keels when the boat is planing but variable in its depth in accordance with the loading experienced by the boat on water so as to adapt the shape of the water-contacting surface to load conditions.
The present invention is concerned to form, by inflation, a multi-keel underwater surface. The proposal uses the flexibility of a fabric skin, stretched over shaped inflated formers, to allow inherently the adaptation of the shape of the underwater surface to load conditions being experienced. This gives a self-compensating underwater surface which retains its good planing performance under all load conditions. The use of parallel twin inflated formers (preferably separate sacs or tubes) to give a generally W-section underwater surface is simplest and at the same time yields very good results. The spacing apart of the parallel formers may be approximately 50% of the deck width of the boat, when only two keels are present.
The floor will provide the reaction surface against which the formers act and will most conveniently be rigid panels extending the whole width of the boat and terminating under, and being supported by, the inflated buoyancy tubes of the boat.
Boats thus constructed may be of any appropriate size but especially suitable will be application of this invention to boats of larger sizes, e.g. 5 metres length upwards, whether with single or multiple engine installations.
A particular boat embodying the invention will now be described with reference to the accompanying drawings wherein:

Figure 1 is a plan view of the forward part of the boat;
Figure 2 is a perspective view of the forward part of the boat;
Figure 3 is a partial, diagrammatic, lateral section;
Figure 4 is a side view and
Figures 5 and 6 show front views of the boat in the water in heavily and lightly loaded condition respectively.

The boat 1 has the usual U-shaped inflated buoyancy tube 2 attached to a flexible fabric floor 3 and a rigid deck 4. The deck 4 is made up of rigid panels extending the whole width of the flexible fabric floor. A forward panel 5 is adpated to the shape of the bow of the boat, a removable panel 6 allows for the assembly of the floor and for access to inflatable keel-formers, and at least one rear panel 7 extends as far as a transom 8 (Figure 4) which closes off the after end of the boat and to which (a) power unit(s) can be attached.
The panel 6 has plates 9 fitting over the adjacent edges of panels 5 and 7 and has expansion braces 10 boltable to panel 5 and then expansible to tighten the floor in the boat. The edges of the panels are trapped under the overhang of the inflated buoyancy tube (Figure 3).
Between the deck 4 and the floor 3 there are fitted two parallel inflatable tubes 11. Respective inflation valves 12 are accessible through parts 13 in the panel 6. The tubes 11 are spaced apart by about 50% of the width of the deck 4.
When the buoyancy tube 2 and the keel-formers 11 are inflated the deck 4 provides a reaction surface from which the tubes 11 act to press the floor 3 downwardly to form a W or catamaran section with twin keels 14 separated by a channel 15, 15'. The panels of the deck 4 are supported by the overhang of the buoyancy tube 2.
As can be seen in Figures 5 and 6 the inherent characteristics of a flexible floor 3 supported by spaced inflated keel-formers is to adapt its conformation to the load being experienced. Greater load deepens the channel between the two keels 14 (15' as against 15). This gives good planing characteristics under any load conditions, something which is difficult to achieve for most flexible-bottom inflatable boats.

Claims

1. An inflatable boat with:

a flexible skin (3) defining the bottom of said boat;

a reaction member (4) having a rigid reaction surface overlying said skin (3); and

inflatable members (11) between said bottom and said reaction surface, each inflatable member (11) when inflated deforming said skin into a keel (14) characterised in that there is a said keel (14) on each side of the centre line of the boat with a constant-width channel (15, 15') between the mutually parallel keels centred on the centre line, the channel formed by said skin being continuous and water-contacting when the members are inflated and the boat is at rest, the channels also being continuous along the parallel keels when the boat is planing but variable in its depth in accordance with the loading experienced by the boat on water so as to adapt the shape of the water-contacting surface to load conditions.

2. An inflatable boat according to claim 1 wherein the reaction member (4) consists of a rigid deck (6) overlying the flexible skin (3).

3. An inflatable boat according to claim 1 or claim 2, wherein the inflatable members are two parallel tubes (11) which on inflation give a twin-keel boat with only one keel (14) on each side of the centreline of the boat.

4. An inflatable boat according to claim 3 wherein the parallel tubes (11) are spaced apart by a distance equal to about half the width of the reaction member ( 14).