This invention relates to a wind powered vehicle, for example a land yacht of the kind having a tricycle frame where two rear wheels support a driver and a single front wheel provides steering.

More specifically, although not exclusively, this invention relates to a land yacht which comprises a load carrying platform supported by ground engaging means operable to support the platform for translational movement over the ground. Usually the ground engaging means comprises wheels in a tricycle layout and a suspension by which the platform is supported by the wheels; but the ground engaging means may comprise skis, roller blades, large balloon tyres in a single front wheel tricycle layout whereby the platform is supported by ground engagement of the tyres over a large area, skate type blades for use on ice, or small floats for use on water. Thus in this specification the term single front wheel tricycle layout extends to use of ground engaging means other than wheels, but in that layout there are two widely spaced wheels or the like at the rear and one at the front. It does not extend to the unconventional alternative of one wheel at the rear and

two at the front.

Land yachts are sold in small numbers to enthusiasts. They are relatively expensive because demand is limited and any production is of low volume.

An object of this invention is to make such a vehicle available to the public at lower cost, and in an arrangement which is safe and easy to sail.

Broadly, by one aspect of this invention, this is achieved by taking components designed and made for a wind surfer and adapting them for use in a tricycle framed wind powered vehicle other than a wind surfer.

Generally a wind surfer consists of a planing hull having a dagger board and a rig comprising an unstayed main mast having a sail whose leading edge (the luff) is attached to the main mast usually via a sleeve, so that the peak and foot of the sail are located at or near the head and the foot of the main mast respectively, and a wishbone boom extends aft wards from a point on the main mast which is above the base of the main mast. Moreover the boom is of a height to enable the operator to stand when holding the boom. Thus, the sail extends a significant extent below the boom, and the boom is at about shoulder

height, that is approximately 1.5 - 1.7 metres above the foot of the mast.

Also, the main mast is normally of a light weight glass fibre reinforced plastic or carbon reinforced material which is highly flexible.

The wind surfer is normally sailed by the operator standing up while holding on to the boom, and the boat is steered by moving the centre of wind pressure on the sail forward or aft; and this is possible due to use of a universal joint at the base of the main mast. In most aspects of sailing, whether tacking, reaching or running the approach is the same as that for a conventional boat, however one exception is that when jibing the sail swings forward of the main mast rather than to its rear in order to transfer from one jibe tack to the other, and another is that the mast can pivot laterally with respect to the boat hull, whereas the mast stays virtually upright with respect to a conventional hull.

The present invention can make use of a windsurfer rig, that is a main mast, a sail having its leading edge (luff) extending from the main mast head to a position close to the foot of the main mast, and a wishbone boom which extends from a position a significant extent above

the foot of the main mast to a trailing corner (clew) of the sail, but is arranged to be sailed in a conventional manner, from a sitting down position at the rear of the vehicle or vessel and using a conventional method of jibing. The sail is controlled by a sheet attached to the boom, as in a conventional boat and is steered by a foot operated tiller or a wheel steering system.

This contrasts with a conventional wind surfer where the operator stands up, or with conventional land yachts where the operator is usually in a lying down position.

Now it is known from German Gebrauchsmuster G91 165377 to use a windsurfer rig with a sailing dinghy, and for this purpose rigid lateral stays extending from the gunwale of the boat support the wishbone at the point where it connects to the mast. However the presence of these rigid stays restricts movement of the sail, and makes it unsuitable for use on a front wheel tricycle layout vehicle which is very narrow at its front end.

The present invention solves this problem by providing a wind powered vehicle or vessel, for example a land yacht, comprising a front wheel tricycle layout base frame, a mounting to receive a main mast for a sail and a boom, and steering means, and further characterised

by a rigid stub mast located forward of the main mast to which the main mast and boom are arranged to be connected by a coupling means connected at the level of the boom.

The stub mast effectively takes the place of the standing operator of a wind surfer in helping to support the main mast and sail against lateral wind forces, while a seated operator at the rear of the vehicle can control steering of the vehicle via pedals or the like and location of the sail via a conventional main sheet force reduction arrangement attached between the vehicle and a rearward end of the boom.

Preferably the boom will be a wishbone boom so that the sail can pass therethrough to extend below the level of said boom.

The importance of the sail extending below the level of the boom is that a lower centre of pressure on the sail can be achieved, and this gives the vehicle a high degree of stability which in turn enables a light weight body to be used and high speeds to be achieved.

Preferably the main mast is a light weight mast of high flexibility.

With such an arrangement, which generally can use the components normally available for wind surfing, a very light body can be used since the system will be stable due to its low centre of pressure from the wind. In consequence a land yacht in accordance with the invention will have good performance in light winds. Moreover, use of a flexible main mast which is stayed at a point connected at the level of the boom, at say 1.5 - 1.7 metres above the mast mounting enables the main mast to stay upright in light winds and to flex in high winds. This means that in high winds a fail safe condition can be achieved where the main mast flexes to spill wind from its upper regions, which reduces the resultant centre of wind pressure and gives greater stability in consequence.

Preferably the main mast is mounted on an axial pivot. This means that it can readily rotate to any point of sailing required. Moreover it becomes very safe since - coupled with the use of the stub mast - it is possible to feather the sail to the direction of the wind at almost all orientations of the vehicle and so it can be easily stopped regardless of its direction simply by letting go of the main sheet.

Conveniently the boom is a wish-bone boom such as is used on a wind surfer and which extends around the main mast

and enables the sail to extend below the level of the boom, and preferably the main mast is very light and very flexible.

A particular advantage is that the vehicle can be sailed from a sitting, rather than standing or lying down, position. Accordingly a seat can be provided on a rear axle and the operator has suitable space beneath the high boom rig of a windsurfer sail.

A land yacht in which this invention is embodied is described now by way of example with reference to the accompanying drawings of which:-

Fig. 1 is a side elevation of the land yacht;

Fig. 2 is a view similar to Figure 1, but drawn to a larger scale with the sail, the boom and the upper portion of the main mast removed;

Fig. 3 is a plan view of Fig. 2;

Fig. 4 is an end elevation of Fig. 2 seen along arrow A in Fig. 2;

Fig. 5 is a fragmentary section of detail B in Fig. 2;

Fig. 6 is a modification of the detail shown in Fig. 5;

Figs. 7a and 7b are further modifications of the detail shown in Fig. 5; and

Fig. 8 and 8a show fragmentary sections of two forms of steering shaft support.

Figs. 1 to 4 show a land yacht comprising a front wheel tricycle chassis 10 on which a streamlined body 11 is mounted. The chassis 10 comprises a transverse rear beam 12 carrying a seat (not shown) on which an operator sits and a forwardly extending main beam 13 which are assembled together in the form of a T. The rear wheels 14 and 15 are journalled at either end of the transverse rear beam 12. The beams 12 and 13 are formed of box- section metal tubing, such as aluminium, which could be plastic coated, or stainless steel, or mild steel, which may be galvanised or plastic coated, titanium or similar materials. Conveniently each beam 12,13 is formed in separate lengths which are fitted together telescopically and bolted together when assembled. These beams can be cranked at their ends, if desired, to lower the centre of gravity of the whole unit.

Referring to Figures 3 and 8, a foot operated tiller

steering system will now be described. A stub shaft 16 is journalled in the main beam 13 at the front end. The stub shaft 16 slopes rearwardly with respect to the main beam 13, having its axis lying in the vertical plane of symmetry of the chassis 10, and has centrally located ball bearings which can be tightened or loosened by two adjustment screws 16a. Adjustment of the tightness of these bearings enables the steering unit to cope with differing conditions; however, referring to Figure 8a, alternatively as a means to reduce maintenance a single bolt with support bushings can be lock-nutted the whole way through a suitably drilled out stub shaft 16.

The upper end of the stub shaft 16 is rigidly joined to the centre of a shorter limb of a crank 17. The front wheel 18 is journalled on an axle 19 which is fixed to the front end of the longer limb of the crank 17 so that the axle 19 is substantially parallel to the shorter limb of the crank 17. A rod 20 is connected by a resilient bush 20A to the end of the shorter limb of the crank 17. The rod 20 runs rearwardly to a pedal tiller bar 20B which is mounted on the main beam 13 for pivotal movement about a vertical axis.

The operator seated on a seat on the rear beam 12 engages the pedal tiller bar 20B with his feet and causes it to

turn for steering. Clockwise motion of the pedal bar 20B, as seen in Figure 3, will cause the land yacht to turn to the right and anti-clockwise motion of the pedal bar 20B will effect a turn to the left. The stiffness of the steering system can then be adjusted by the screw 16a, to cope with different conditions (assuming this feature is employed) .

A main mast 21, which is a conventional wind surfer mast, is mounted on the main beam 13. For this purpose, there is a novel fitting 22 at the foot of the mast 21. The fitting 22 has an axial bore 23 with a domed blind end formed in it from its bottom. An upstanding pin 24 which is mounted on the main beam 13 is received in the bore 23. The interengagement of the pin 24 in the bore 23 comprises a swivel joint which allows limited angular movement of the main mast 21 from the vertical but also allows the mast 21 to be rotated through about 300 degrees, or more, about the pivot point of the swivel joint. This enables the main sail to be feathered so as to loose drive from a wide variety of points of sailing by simply releasing the main sheet - and so becomes an important safety feature.

The main mast 21 carries a wind surfer sail, that is a sail whose luff is sleeved around the main mast 21, whose

peak is attached near the head of the mast, whose lower part extends through and below a wishbone boom 27 and whose lower corner (tack) is attached near the foot of the mast. The sail has conventional cross battens.

An auxiliary stub mast 25 (about 1.6 metres high) is rigidly mounted on the main beam 13 forwards of the swivel joint by a rigid, strong mounting 26. The stub mast 25 is stiff but can flex. It may comprise a bar of an extruded plastics material (eg. nylon, PVC, or a composite such as glass fibre reinforced plastics material or a carbon fibre material) which may be a solid or a heavy gauge tube. If a plastics tube, the mast 25 may be reinforced by a stainless steel or an aluminium rod for either the whole or part of its length. The mounting 26 may be a welded fabrication, an investment casting or a forging. The material from which the mounting 26 is made may be titanium, stainless steel or aluminium or welded mould steel. A suitable arrangement for the mounting 26 is to use an upstanding reinforced mast step welded to the main beam 13 and having a bolt which holds the stub mast in place. The stub mast should be a sliding fit in the mast step which allows a very slight degree of movement but remains firmly held upright.

The conventional windsurfer wish-bone boom 27 is attached to the main mast 21 in a conventional manner as is shown in Figure 1, and has a 2:1 reduction main sheet 30.

A simplified version is shown in the drawings but other arrangements of main sheet may be preferred. For example the main sheet arrangement can go from a first mounting point relatively close to the aft end of the boom, to the boom at that point and then may be led forward towards the foot of the mast, to be re-directed back to the operator via a flexibly mounted standing block at the foot of the mast. This makes it easier for the operator to control the main sheet, since he will then be pulling it towards himself. The first mounting point may be at the rear of the seat (not shown) or may be on a separate extended inverted V-beam behind the seat.

In addition, the boom 27 is coupled to the stub mast 25. Figure 5 shows coupling of the boom 27 to the tubular stub mast 25 by a hook 28 which is a loose fit in a bush 29 in the top of the stub mast 25. A similar bush may also be provided to support the lower end of the shaft of hook 28. The hook 28 is hooked over the wish-bone boom 27 in front of the main mast 21 and just above the top of the stub mast 25. A cord 31, which is tied to a ring 32 at the exposed end of the hook 28 within the bush

29 whilst allowing limited movement of the hook 28 and which is held by a jamming cleat 33 on the stub mast 25, retains the hook 28 in position relative to the stub mast 25 and keeps the wishbone in place. Also in the case of a "capsize" the main mast is also kept in position.

Figure 6 shows the hook 28 may be similarly fitted into the bore of a tubular stub mast 25A of PVC or a composite such as carbon fibre.

As an alternative to the hook coupling shown in Figures 5 and 6, the boom 27 may be coupled to the stub mast 25 by a pin 34 which is fitted adjacent (Figure 7a) or through (Figure 7b) the wish-bone end 35 adjacent to the clamp 36 by which the boom 27 is clamped to the main mast 21, the pin 34 depending from the boom 27 into the bore of the bush 29 at the top of the tubular stub mast 25. A second bush may be provided to support the lower end of the pin 24.

In this arrangement the main mast is clamped to a coupling which also carries the pin 34 and enables the main mast to move in an arc round the stub mast 25 to a position dependent on the point of sailing operational at that time. The wishbone boom rotates correspondingly.

As a result of the coupling of the boom 27 to the stub mast 25, the wind loads on the sail are transferred to the stub mast 25 in a way similar to that of a wind surfer holding the boom 27 so that the main mast 21 is only subjected to stresses which are similar to those to which it would be subjected when used on a windsurfer for which it was designed.

As a result of fitting the land yacht with the windsurfer mast 21 and boom 27, and the stub mast 25, the land yacht has far greater stability and can be used on poorer terrain, such as grass, than is usually the case with conventional land yachts. Also it is easier and safer to use than conventional land yachts. This is because the windsurfer rig has a lower centre of pressure and can remain in an efficient setting as the sail is let out. Power can still be obtained efficiently on a broad reach as the main mast 21 rotates to maintain the best aerodynamic shape, unlike land yachts fitted with a conventional mast and boom. Also, as the sail is let out further, the main mast 21 can rotate until the sail becomes feathered, providing no power regardless of the orientation of the land yacht to the wind. Hence the land yacht is safe as it does not run out of control as power can be removed by simply letting go of the main sheet, or by luffing up via the steering arrangement.