GB2251583A - Water craft - Google Patents

Abstract

A water craft having a central hull located between two outrigged floats wherein each float is joined by a bridge member to the hull at a root position extending parallel to the longitudinal axis of the hull the centre of the root position lying behind the longitudinal mid-point of the hull; and each float is located relative to the hull so that its centre of buoyancy is forward of the root position. Each float contributes less than 20 % of the buyonacy of the combined floats and hull. Each float or an extension thereof is equipped with a separate hydrofoil surface which is located on the float at a position behind the centre of buoyancy of the float. Preferably the craft is equipped with at least one sail to provide propulsion such that the, or at least one, sail is supported by way of a luff spar mounted on the upper end of a bipod mast whose lower end is supported on the hull. The lower end of the bipod is pivotably mounted on the hull to enable the bipod, luff spar and the sail to be lowered and raised between an erected working position and a lowered stowed position on or adjacent the hull.

Description

WATER CRAFT This invention relates to a water craft. In particular it is concerned with a light multi-hulled water craft which term is taken to include craft having a major hull with outrigged floats.

Multi-hulled craft driven by sails are used for a wide range of recreational activities. Multi-hulled craft offer a number of advantages over single hulled ones. In designing a single hulled craft a balance has to be struck between various requirements which have to be met by the hull such as offering minimal resistance to propulsion, the ability to carry a load and the provision of lateral stability. These requirements are not necessarily readily compatible. Thus while increasing beam provides for increased lateral stability and increased load carrying capacity it also increases frontal resistance and power consumption for a given speed. In designing a multi-hulled craft the compatibility problem is not necessarily so complex. Typically the load carrying requirement can be treated substantially independently of the stability requirement.

According to a first aspect of the present invention there is provided a water craft having a central hull located between two outrigged floats characterised in that: 1 each float is joined by a bridge member to the hull over a root length which either itself extends, or has a component extending, parallel to the longitudinal axis of the hull, the centre of the root length lying behind the longitudinal mid-point of the hull; 2 each float is located relative to the hull so that its centre of buoyancy is forward of the centre of the root length. Preferably each float contributes less than 20% of the buoyancy of the combined floats and hull.

According to a second aspect of the present invention in a water craft according to the first aspect each float or an extension thereof is equipped with a hydrofoil surface which is located to act on the float at a position behind the centre of buoyancy of the float in relation to the normal forward direction of the craft.

According to a third aspect of the present invention a water craft according to the first or second aspect thereof is equipped with at least one sail to provide propulsion. Preferably the, or at least one, sail is supported by way of a luff spar mounted on the upper end of a mast in the form of a bipod whose lower end is supported on the hull. Typically the lower end of the bipod is pivotably mounted on the hull to enable the bipod, luff spar and the sail to be lowered and raised between an erected working position and a lowered stowed position on or adjacent the hull.

An exemplary embodiment of the invention will now be described with reference to the accompanying drawings of two embodiments of a canoe of which Figures 1 to 3 relate to the first embodiment and Figures 4 to 9 relate to a second. Of the drawings: Figure 1 is a perspective view Figure 2 is a plan view; Figure 3 is a front elevation in the direction of arrow III in Figure 2; Figure 4 is a side elevation in the direction of arrow IV in Figure 2; Figure 5 is a perspective view of the canoe when equipped with a sail; and Figure 6 is of means for raising and lowering the sail shown in Figure 5; Figure 7 is a view from the underside of a component whose form and function is considered in described in more detail in relation to Figures 8 and 9; and Figures 8 and 9 are partial side elevations of a canoe in different speed conditions.

Items appearing in more than one figure are given the same. reference in all figures in which they appear.

FIGURES 1 TO 4 Canoe 11 has a main hull 12 with longitudinal axis L. Apart from a cockpit 13 the hull 12 is substantially closed by fore deck 14 and after deck 15. The canoe is fabricated from glass fibre reinforced material which provides for a light but extremely strong structure. A watertight panel 16 closes aperture 17 giving access to a stowage space in the hull 12 behind the cockpit 13 for camping and/or other gear.

Wings 19A, 19B are removably but rigidly secured to the hull 12 behind the aperture 17 to provide a bridge member 19 extending across the hull to provide for the location of floats 20, 21 symmetrically on either side of axis L. By having the bridge in two parts the canoe can be readily dis-assembled into reasonable size parts for readily handling and transportation for example on and in a passenger car. Wing 19A is secured by bolts to hull 12 at a location defining a root L2 parallel to axis L. Likewise wing 19B is secured to the hull 12 at a location defining a root L3 parallel to axis L. The roots L2, L3 are located in the rear part of the canoe 11 that is to say aft of the midpoint of the canoe length on axis L.

The bridge 19. has at its outer ends 20, 21 floats (respectively floats 22, 23).

Leading edges 24, 25 of the bridge 19 are shaped to provide sufficient clearance so that a paddler seated in cockpit 13 can readily ply a single or double ended paddle to propel the canoe 11 without the paddle striking the bridge 19.

The canoe is about eighteen feet long and has an overall beam of about nine feet. As shown in Figures 1 to 3 the canoe 11 is a readily paddled vessel for recreational purposes. Stowage space 18 allows for the conveyance of a substantial amount of material for camping or other use. The floats 22, 23 provide lateral stability for the canoe 11 while not detracting from is fast performance. This is advantageous for generating confidence in a novice userparticularly a physically handicapped person. The volume of the floats 22, 23 relative to the hull 12 is such as to ensure that the buoyancy provided by the floats os not so great as to impose excessive loadings on the junction between wing 19 and the hull 12.Typically the buoyancy contributed by float 22 or 23 is 20% or less of the total buoyancy of the combine hull and both floats, FIGURE 5 AND 6 Figure 5 shows the forward part of a canoe 11 identical to that described in connection with Figures 1 to 4 saving that it is equipped for sailing. Steering is carried out by way of a rudder mounted at the rear end of the hull and operated by way of lines coupled to a pedal arrangement in the cockpit for actuation by the feet of a user. Alternatively the lines can be secured at their front end to grips for operation by the hands of a user.

Sail 40 is of triangular shape with two full width battens 41A, B extending from leech 43 of the sail to luff 42. Luff 42 of the sail is in the form of a pocket retaining spar 44. Foot 45 of the sail is secured to a boom 46 by lashing (typically lashing 46A, Figure 6). The after part of the boom 46 is controlled in a known manner by sheet S.

The spar 44, and so sail 40 and boom 46, is supported by a universal joint 47 at top 48 of a mast 49 made up of bipod legs 50, 51. Lower ends 52, 53 of, respectively legs 50, 51 are pivotably mounted on, respectively, mountings 50A, 50B located on either side of foredeck 14 so as to allow the legs 50, 51 to pivot about lateral axis 54. By locating the sail 40 and its associated spar 44 and boom 46 on the mast by way of a single universal joint 47 the sail and mast combination can be readily raised, lowered and the sail sheeted while the craft is underway as will be described in more detail hereafter.

Once mast 49 is erected rearward movement of the top 48 of mast 49 is limited by a line 55 which runs from an attachment 55' (on the mast 49 in the region of the joint 47) to a block 56 mounted in the bow of the canoe through which the line 55 runs to pass rearwardly to a cleat 60 (shown diagrammatically) mounted on the front end of cockpit 13. The line 55 also serves to lower the mast 49 in a controlled manner forwardly onto the fore deck 14 when the sail 40 is no longer to be used.

Reference is now made to Figure 6. Forward end 61 of line 62 (shown single chain dotted) is secured to anchorage 56A of the block 56. Line 62 extends aft through a ring 57, up to a block 58 on the underside of the boom 46, down to a deck mounted block 59 and aft to the cockpit 13 which has mounted in or near its front end a jamming cleat 63 for the rear end of line 62.

Ring 57 is secured to one end of a line 64 (shown continuously chain dotted) which passes downwardly through deck mounted block 65 and from thence aft to a third jamming cleat 66 mounted near to cleats 60, 63 to provide for ready manipulation from the cockpit 13.

By leading the line 62 in this way and securing it in cleat 63 it provides for the erection of the mast 49 from a stowed position lying on the fore deck 14 to the position shown in Figure 4. With the mast 49 secured erect and the sail 40 drawing a line 64 functions by way of ring 57 on line 62 as a boom vang to keep the boom 45 down and so sail 40 relatively flat. The sail rotates about an axis A defined at one end by universal joint 47 and at a lower end by block 58. In this way tack 40A of the sail can move freely past the mast 49 when tacking.

The mast 49 can be lowered from the raised position shown in Figures 4 and 5 by releasing forestay 55 from the cleat 60 and drawing it so as to pull the top of the mast 49 forwardly. Thereafter the mast pivots forwardly about axis 54. The universal joint 47 enables the sail together with the lower part of the spar 44 and boom to readily pass through the space between the legs 51, 51 so that the sail 40 mast spar, boom and sail readily bundle up to lie on the foredeck 14. In this way the sail can be readily raised, lowered and trimmed from the cockpit while underway.

FIGURES 7, 8 AND 9 When sailing it has been found possible to substantially increase the speed of the canoe 11 by making use of a hydrofoiling surface or surfaces on each float.

Figure 7 shows from beneath a float 22 with hydrofoil 71 secured to it extending on either side of the float 22 as wings 72, 73.

Figures 8 and 9 shows float 22 located on end 20 of bridge 19 whose inboard end is secured to the hull 11 (shown only in broad outline) to give a root L2 as described earlier.

Figure 8 represents a still condition with the canoe 11 normally loaded and trimmed and stopped or travelling slowly at a low displacement speed the float 22 is partially immersed to a water line 73. Centre of buoyancy 74 of the float 22 is located forwardly of hydrofoil 71 on longitudinal axis 74 which under these conditions is effectively horizontal with lower surface 75 lying on plane H1. The Upper and lower surface of the wings 72, 72 of the hydrofoil 71 have aerofoil shapes which in this situation has a neutral angle of attack relative to water flowing past it.

Figure 9 shows the situation when the canoe speed has risen to the extent that the float is completely immersed and the longitudinal axis H1 is now inclined upwardly relative to the direction of travel and angle of attack A between the underside of hydrofoil 71 and the horizontal has increased to about 30 at which point the surface 75 causes hydrodynamic forces to act with a upward resultant increasing the lift provide by the float 22 to the canoe 11 as a whole. The bridge 19 is designed to provide for a degree of twisting about axis T The consequent improvement in windward and downwind performance arising from the effect of the hydrofoil wings is substantial as against that arising from purely displacement performance of the canoe.

It will be apparent that the sailing version of the canoe provides a versatile craft. The overall stability of the craft facilitates its use by a learner particularly one who is physically handicapped. In particular the simple controls are readily adapted to meet the needs of a person lacking one or more limbs or with back trouble. The second embodiment has a sail of 35 square feet area with a 10' spar and a boom of 8'. The performance with this amount of sail has been found comparable with that of a sail board downwind and considerably better going upwind. It will be appreciated that this performance could be improved on given a larger sail area and consequential strengthening of the bridge member and its attachment to the hull.

Claims (7)

CLAIMS 1 A water craft having a central hull located between two outrigged floats characterised in that:

1 each float is joined by a bridge member to the hull over a root length which either itself extends, or has a component extending, parallel to the longitudinal axis of the hull, the centre of the root length lying behind the longitudinal mid-point of the hull;

2 each float is located relative to the hull so that its centre of buoyancy is forward of the centre of the root length.

2 A water craft as claimed in Claim 1 characterised in that each float contributes less than 20% of the buoyancy of the combined floats and hull.

3 A water craft as claimed in Claim 1 or Claim 2 characterised in that aspect each float or an extension thereof is equipped with a hydrofoil surface which is located to act on the float at a position behind the centre of buoyancy of the float in relation to the normal forward direction of the craft.

4 A water craft as claimed in any preceding claim characterised by the provision of at least one sail to provide propulsion.

5 A water craft as claimed in Claim 4 characterised in that the, or at least one, sail is supported by way of a luff spar mounted on the upper end of a bipod whose lower end is supported on the hull.

6 A water craft as claimed in Claim 5 characterised in that the lower end of the bipod is pivotably mounted on the hull to enable the bipod, luff spar and the sail to be lowered and raised between an erected working position and a lowered stowed position on or adjacent the hull.

7 A water craft as hereinbefore described with reference to and as illustrated in the accompanying drawings.