EP0438488A1

EP0438488A1 - Sailing vessel

Info

Publication number: EP0438488A1
Application number: EP89911835A
Authority: EP
Inventors: Keith Stewart
Original assignee: STEWKIE SYSTEMS Ltd
Current assignee: STEWKIE SYSTEMS Ltd
Priority date: 1988-10-15
Filing date: 1989-10-13
Publication date: 1991-07-31
Also published as: GB8824210D0; AU4422789A; WO1990003912A3; WO1990003912A2

Abstract

Voilier (10) comprenant deux coques (11, 12) qui sont reliées par des éléments (tels que des tubes gonflables (13)) capables de modifier la position longitudinale d'une coque par rapport à l'autre (11, 12) en cours d'utilisation, et, éventuellement, de varier la distance séparant les deux coques (11, 12). Le voilier (10) est muni d'un ensemble mât se composant d'un mât proprement dit et d'un volet (15), le mât (14) pouvant pivoter et ou se déplacer vers les côtés et/ou d'avant en arrière pendant son utilisation pour modifier ses caractéristiques de navigation. Les différents éléments du bateau (10) comme les coques (11, 12), les tubes (13) et le mât (14) se composent de chambres à air indépendantes ou de groupes de chambres gonflables.Sailboat (10) comprising two hulls (11, 12) which are connected by elements (such as inflatable tubes (13)) capable of modifying the longitudinal position of one hull relative to the other (11, 12) in during use, and possibly to vary the distance separating the two shells (11, 12). The sailboat (10) is provided with a mast assembly consisting of a mast itself and of a flap (15), the mast (14) being able to pivot and / or move to the sides and / or from before. backward during use to modify its navigation characteristics. The various elements of the boat (10) such as the hulls (11, 12), the tubes (13) and the mast (14) consist of independent air chambers or groups of inflatable chambers.

Description

SAILING VESSEL This invention relates to a sailing vessel and it is an object of the invention to provide an improved sailing vessel.

The invention provides a sailing vessel including a pair of elongate hulls connected together, a sail, and means for effecting relative forward/aft movement between the hulls. The invention also provides a vessel having an upstanding sail, wherein the sail consists of an inflatable mast body and a flap of flexible material. The invention also provides a vessel having a sail including a mast portion and a flap portion, the mast portion being mounted and/or constructed so that its upper end can be moved relative to its lower end.

Preferred embodiments of the invention may incorporate one or more of the following features.

1. A sail can upstand from one of the hulls. ²- ^A sail can upstand from structure connecting the two hulls.

3. Relative movement between the hulls can be such as to move the centre of pressure of the sail forward and aft of the centre of gravity of vessel. 4. The hulls can be connected by arms.

5. The arms can be flexible. 6. The arms can be in form of rigid links pivoted to allow movement in a horizontal plane.

7. The arms can be additionally constructed or arranged to allow bending in the vertical plane to allow the separation between the two hulls to be varied.

8. Interconnecting arms can be in the form of pivoted levers or can be in the form of a lazy tongues mechanism. 9. The means interconnecting the hulls can be in the form of inflatable tubes.

10. One or more guy ropes can be connected to the tubes and the hulls and arranged to be tensioned and/or slackened to control bending of the tubes to fix a longitudinal relative movement between the hulls.

11. The tubes can be arched transversely of the hulls to give sea clearance to the tubes.

12. Winches can control the guy ropes.

13. The hulls can consist of a main hull and an outrigger hull.

14. The sail can be on the main hull.

15. The sail can be on the outrigger hull.

16. The main or outrigger hull can have a cross-section which presents a flat or concave submerged face to leeward of the vessel.

17. Each hull can be of inflatable construction.

18. Each hull can consist of a plurality of adjacent inflatable tubes. 19. The tubes can be surrounded by an outer envelope. Individual tubes can be connected by sewing together or by touch-and-close fasteners such as those sold under the Registered Trade Mark VELCRO or CRIC-CRAC. 20. Each tube assembly can consist of an air impermeable inflatable inner bag in conjunction with an outer layer of tough non-extensible wear resistant material. 21. The tough inextensible outer covering can be covered by a further resilient expansible covering of, e.g. polyurethane to enhance the appearance and to aid deflation by exerting an inward deflating force. 22. The inner air-impermeable material can be laminated to the external reinforcing tough material by means of a flexible and extensible connecting adhesive, for example an extensible epoxy resin.

23. The various tubes and components of the vessel can be constructed in accordance with the general method described in British Patent No. 8727166 ( ) . 24. The sail can consist of a body and said flap.

25. The flap can be continuously attached to the body or can be connected at spaced intervals to create a slot effect between the flap and the mast body.

26. The mast body can consist of a plurality of adjacent inflatable tubes.

27. The tubes can be disposed within a surrounding envelope.

28. One or each tube of the mast body can have its arranged to be variable in use so as to alter aerodynamic characteristics of the mast portion to suit different conditions.

29. The shape of the mast portion can in this way be alterable from a profile which suits a port tack to a configuration which supports a starboard tack.

30. The mast is arranged to be rotatable in order that the vessel can sail in each direction.

31. Each hull can be symmetrical in order that the vessel can sail in either direction in the manner of a proa.

32. The mast structure can contain port and starboard laterally extending tubes, and such tubes can themselves be pressure variable in order to allow bending of the mast from port to starboard to take up a curved configuration under certain conditions.

33. Comparable variations can be made in fore/aft tubes within the mast body to allow the mast to curve forwardly or rearwardly. 34. Alternatively, and/or in a combined manner movement of the mast head can be controlled both by bending the mast and by tilting the whole axis of the mast relative to a mounting.

35. The mast body can have a leading edge and a trailing edge, the trailing edge merging towards said flap and the leading edge being stumpier than the trailing edge.

36. The flap can be in the form of a simple sheet of inextensible flexible material, or can itself be in the form of an inflatable flexible thin wedge.

37. Flexing and/or tilting of the mast can be effected by guys connecting the mast to its mounting hull or to other structure of the vessel.

38. The guys can be operated by winches.

39. Each hull can have a selected one or ones of its tubes separately and independently inflatable and/or deflatable at the will of a sailor to alter characteristics of that hull to suit certain conditions. Deflation of any particular tube, or other shaped inflatable component, can be effected by operation of an appropriate valve.

40. Re-inflation of a deflated section, which may be necessary for some purposes, can be effected by allowing air to enter from a reservoir.

41. The reservoir can be a container of compressed gas carried on the vessel.

42. Preferably the container of compressed gas can be one of the tubes.

43. Said one tube can be a major component of the main hull and is inflated to a pressure of 100-200 psi

(other units) to give enhanced rigidity to the main hull. 44. As a further invention there is provided a vessel including a plurality of hulls, each hull consisting of a plurality of inflatable chambers, at least some of those chambers being interconnected at line of _Λ ,_„_.«•,_.», O 90/03912

-6-

central means of touch-and-close fasteners such as those sold under the Trade Marks VELCRO and CRIC-CRAC or by an adhesive. The containers can be tubes arranged to lie side by side and be connected by such 5 touch-and-close fasteners at their meeting lines.

The invention will be described further, by way of example, with reference to the accompanying drawings wherein:-

Fig. 1 is a schematic plan view of a preferred 10 vessel of the invention;

Fig. 2 is a side elevation of the vessel;

Figs. 2a and 2b are cross-sectional views illustrating a body portion of a mast of the vessel;

Fig. 3 is a plan view of the vessel with its mast 15 tilted;

Fig. 4 is a plan view of the vessel with its mast tilted and its beams warped;

Fig. 5 is a front view of the vessel:

Fig. 6 is a schematic cross-sectional view on line 20 6-6 of Fig. 5;

Fig. 7 is a view similar to that of Fig. 5 with warped beams;

Fig. 8 is a cross-section on line 8-8 of Fig. 7;

Fig. 9 is a view comparable to that of Fig. 5 but 25 taken from the stern;

Fig. 10 is a cross-section on line 10-10 of Fig. 9;

Fig. 11 is a view comparable to that of Fig. 9 but with the beams having been warped in the horizontal plane;

Fig. 12 is a cross-section on the line 12-12 of Fig.11; Fig. 13 is a side elevation of the vessel from windward;

Fig. 14 is a view comparable to that of Fig. 13 but with the mast canted forwardly.

Fig. 15 is a bow view with the mast warped and with the sail in a reaching position;

Fig. 16 is an illustration of the vessel in its running condition with the beams and the mast both warped;

Fig. 17 is a view comparable to that of Fig. 13 but with the sail canted to windward by the mast being warped; and the centre of pressure moved forward by beam warping

Fig. 18 is a view comparable to that of Fig. 14 but seen from windward; Fig. 19 is a front view of the vessel with the beams warped in the vertical plane to increase sea clearance between the beams and the sea surface; Fig. 20 is a view similar to Fig. 19: Fig. 21 is a view comparable to Fig.15 but showing a HAPA deployed;

Fig. 22 is a side schematic elevation showing the main hull;

Fig. 23 is a side elevation showing the main hull; Fig. 24 is an enlarged cross-sectional view illustrating the outrigger hull;

Fig. 24a is a schematic cross-sectional view through the main hull 12; Fig. 24b illustrates internal construction of the outrigger hull 12;

Fig. 25 is _.an enlarged schematic cross-sectional view illustrating the mast and sail construction;

Fig. 25a and 25b illustrate modification of the mast structure to suit different tacks;

Fig. 26 illustrates the vessel with an attached HAPA;

Fig. 27 is a side elevation with a cutaway showing the HAPA in use; Fig. 28 is a front perspective view of the HAPA; Fig. 29 is an end elevation showing the HAPA in use;

Fig. 30 is a side elevation of the HAPA; Fig. 31 is a plan view of the HAPA; and Fig. 32 illustrates the relationship of the HAPA to the outrigger hull 12.

A preferred vessel 10 of the invention has several inventive features and these will be discussed individually under the following headings. General Layout

The vessel 10 comprises a main hull 11 and an outrigger hull 12 interconnected by beams in the form of transversely extending inflatable tubes 13. A leading edge mast part 14 upstands from the hull 12 and supports a flap portion 15 of a sail assembly constituted by items 14 and 15.

As is shown throughout the drawings, but as is best seen in Figs. 3 and 4, the hull 12 and the hull

11 are arranged so that there can be relative longitudinal movement between them. In Figs. 3 and 4 such movement is shown in the form of movement of hull

12 relative to hull 11, but it will be appreciated that it could equally well be considered in the opposite way. The beams 13 are in the form of inflated tubes and therefore have a degree of flexibility. The hull 12 and the hull 11 are interconnected by means of cables 16 and 17 which connect with respective winches 18, 19 which can be operated in unison to effect relative fore and aft movement between the two hulls. If necessary, one or more of beams 13 can be reinforced by or substituted for by longitudinally extending incompressible members, for example flexible rods or tubes, which would allow the beam 13 to flex in the horizontal and in the vertical plane, but will not allow them to be longitudinally compressed by tension of the cables 16, 17. As has been mentioned, the sail arrangement consists of the mast portion 14 and the flap portion

15. The mast portion has a central core tube 40 which is secured to the outrigger hull 12 at its lower end and to whose upper end are attached mast control guys 21, 22. The guys 21, 22 are controlled at winches 23, 24. The trailing edge of the sail flap 15 has connected thereto twin sheets 25 and 26 which are again controlled by different sections of the winches 23 and 24.

The Main Hull

Referring now to Figs. 22, 23 and 24, it will be seen that the main hull is some 400 mm deep at its deepest and about 6.5 m in length. The hull 11 is composed of six longitudinally extending and parallel lying inflatable assemblies 27, 28, 29, 30, 31 and 32. Each of the tube assemblies is of the same construction and this construction is not shown in detail. However, each tube consists of an inner layer of gas impermeable expansible material surrounded by a flexible envelope of reinforcing tear and scratch-resistant high tensile material which in itself does not need to be gas impermeable but can be if desired. When particular strength is required, (for example portions of the inflatable assemblies which might be subjected to chafing or friction such as the top of the assembly 27, exposed lateral portions of the assemblies 28 and 29) . The inflatable inner and the reinforcing outer can be laminated together using an adhesive such as an expansible resin such as expansible epoxy resin.

The upper assembly 27 is a main tube assembly of the main hull and is some eight inches (200 mm) in diameter. This assembly 27 can be inflated to a particularly high pressure, for example at least 100 psi, or up to 200 psi or mo're and can serve as a reservoir for inflating and/or reinflating others of the tubes as will be later described.

Assemblies 28 and 29 could be described as the beam tubes of the main hull 11 and give it stability. Assemblies 30, 31, 32 are of progressively diminishing size from six inches (150 mm) diameter down to three inches (75 mm) diameter and can be considered as keel tube assemblies. As will be apparent from Fig. 24 and also from comparable other Figures such as Fig. 5, keel tube assemblies 30, 31, 32 are arranged to be angled towards the outrigger hull 12. This arrangement creates on the rearward facing side of the main hull 11 a cavity indicated at 33 which tends to reduce leeway.

The tube assemblies 27, 28, 29, 30, 31 and 32 are preferably (but not essentially) enclosed within a surrounding envelope 34 of high tensile flexible wear-resistant material. If desired, the envelope 34 can be of a resilient expansible material. An expansible material can serve as an aid when deflating the hull as it tends to urge the air out of the assemblies 27-32.

The individual tube assemblies 27-32 are attached to each other using touch-and-close fasteners at their lines of contact and the envelope 34 can be sewn to the outer shell of assembly 30 at the positions illustrated at 35. The envelope 34 can be of a high tensile material such as SPECTRA. A second envelope of attractive, resilient material can surround the envelope 34 to improve appearance and aid deflation. As seen in Fig. 24a the outrigger hull 12 is generally circular in cross-section and consists of a core assembly 35 and eight surrounding inflatable assemblies 36. The assemblies 35 and 36 are of construction comparable to the assemblies described in relation to the main hull and will not be described further. However, an envelope 37 of hard-wearing high tensile material surrounds the assemblies 35 and 36. As is schematically illustrated in Fig. 24b the tapered bow-like profile of both the main hull and the outrigger hull is achieved by progressive termination of the various tubes to give the general overall profile which is shaped by the overlaid envelopes 34 and 37. If necessary voids formed within the envelopes at these areas could be filled, for example by expansible foam or the like to present a smooth streamlined bow surface to the water. Bow surfaces are necessary at each end of each hull in order that the structure can act as a proa. It will be noted that the vessel as a whole has neither rudder nor centre boards or lee boards and is steered entirely by altering its geometry. The Sail As will be best seen in Fig. 2, (but also as appears in the cross-sectional views of Figures, for example, 8 and 12) , the sail (as previously mentioned) has a mast portion 14 and a flap portion 15. The flap portion is continuous with a rear edge of the mast part 14 although it could be mounted parallel thereto to take advantage of the slot effect. The mast portion 14 in itself resembles an aerofoil (see Fig. 25) . The mast portion 14 of the said arrangement 14, 15 is shown in schematic cross-section in Fig. 25. In a manner comparable to the hulls 11 and 12 the portion 14 consists of several tube assemblies 38, 39, 40, 41, 42, 43, 44 and 45. Tube assemblies 38 and 39 can be said to define a leading edge portion 46 and assemblies 41, 42 and 43 can be said to define a trailing edge portion 47. Assemblies 38 and 39 are of different sizes to give the leading edge portion 46 a stubbier, less tapered profile than has the trailing edge portion 47. Laterally and between assemblies 39 and 40 are provided narrower stiffening tube assemblies 44 and 45, one to port and one to starboard. The assemblies 44 and 45 can be arranged to be alternately inflated and deflated depending on whether a port or starboard tack is to be sailed.

Considering Fig. 25 as a plan cross-sectional view, if it is desired to sail on a starboard tack tube assembly 45 would be inflated to increase the leeward chord length whereas 44 would be deflated to shorten the windward chord length thereby creating an asymetrical section which increases the speed of airflow on the leeward side thereby further decreasing the leeward pressure and increasing the aerodynamic force and speed of vessel. Conversely when it is desired to sail to port as shown in Fig. 25a tube 44 would be inflated and tube 45 would be deflated. During the going about manoeuvre air could be transferred from one tube 44 to the other 45 or vice versa until as shown in Fig. 25b they equalise each other, whereupon spine assembly 40 could top up to full pressure. The outside cover 48 can assist in the transfer of air from one tube 44 to the other if it is an ostensible material such as polyurethane which contracts and expands according to the pressure exerted on it.

An arrangement of valves (not shown) can be provided to ensure that such exchange of air occurs automatically upon operation of control apparatus under the infuence of the crew.

Inflatable tube assembly 40 can be referred to as a spine assembly and can possibly be inflated at a higher pressure than the rest to give rigidity to the assembly. Fig. 25 a, b indicates some of the pressure variations which can be effected within the mast. Spine assembly 40 connects with the hull 12 by means of a mechanical pivot or the like which is not shown in any detail. The mechanical pivot allows the sail to turn about a vertical axis and, if necessary, to pivot about a horizontal axis. However, in view of the fact that the sail portion 14 is normally intended to be warped in use, it is to be expected that the connection between the lower end of the boom and the hull 12 will only allow for rotation of the sail about a vertical axis (considering the outrigger to lie horizontally) . The tube assemblies 44 and 45 can also be alternately inflated and deflated in order to help to warp the mast when sailing on the port or starboard tack.

As has been previously mentioned in relation to the construction of the hulls 11 and 12, the mast part 14 can be surrounded by an outer envelope 14 of reinforcing material. The component tube assemblies of the mast can be adhered to each other or can be fastened to each other with a touch-and-close fastener as previously described.Each inflatable assembly can comprise an inner gas impermeable tube surrounded by an outer reinforcing member, the tube and the reinforcing member being laminated together at places where reinforcement is desired. The laminating material can be an adhesive such as expandable epoxy resin.

The flap part of the sail is triangular and generally conventional in operation. Along its vertical leading edge it is secured to the extremity of the mast portion 14 adjacent tube assembly 43. Operation of the Vessel

Referring firstly to Fig. 3, the central relative positions of the main hull 11 and outrigger hull 12 are shown, that is the condition wherein the cables 16 and 17 are of equal length and the hull 12 lies parallel to the main hull 11. The transverse beams 13 lie at right angles to both hulls. In this condition under the influence of a wind W, the vessel proceeds on the port tack in the direction of the arrow P and the vessel will sail close-hauled. Alteration of the respective length of the sheets 25, 26 determines the angle which the vessel axis adopts in relation to the wind direction as in a conventional vessel. Fig. 4 illustrates how the cables 16, 17 have been adjusted to draw the outrigger hull 12 towards the bow of the main hull 11. This places the centre of pressure (C/P) of the sail more forwardly of the line of the boat's centre of gravity (marked C of G) than shown in Fig. 3,and this causes the vessel to travel further down wind, e.g. on a broad reach.

Figs. 5, 7, 9 and 11 show the vessel in operation with the beams alternatively straight and curved to cause alteration of direction. Conversely to the above described action, if the cable 17 is shortened whilst the cable 16 is relaxed the centre of pressure moves to the right of the centre of gravity in Fig. 4 and the vessel turns to port. The above-mentioned Figures also illustrate how the asymmetric shape of the main hull prevents (or discourages) the vessel from making leeway. Figures 13 and 14 show how the mast can be warped forward. The mast/sail will usually curve to be concave although it is shown simply bent to still remain in a straight line. This can assist the angle of attack of the wind on the sail and improve sailing characteristics. The angle of tilt of the mast is controlled by the mast guys 21,22.

Fig. 16 shows how the vessel looks when sailing from its bow in the running condition. With the wind blowing in the direction of the arrow W and the weight of the sailor over the main hull 11, the outrigger hull 12 can be lifted from the water. The necessary force to lift this can be generated by tilting the mast forward and canting it sideways to port. This generates an upward component ofAift which raises the outrigger hull 12 from the water. This, clearly, reduces the drag on the vessel.

Fig. 19 illustrates a variation wherein the inflatable tubular beams 13 are caused to be upwardly convex by means of interlinking cables 49 which can be tensioned before inflation of the beam 13. This arrangement lifts the beam 13 clear of the water and facilitates performance in rougher water.

Fig. 20 again shows the vessel wherein the beams are arched as in Fig. 19 and the vessel is otherwise operating as described in relation to Fig. 16, that is to say only the main hull 11 is immersed and its concave cavity 33 is resisting travel to leeward. It will be appreciated that with a light vessel of this type the position of the crew, be it an individual sailor or two or more persons, will greatly affect the performance of the vessel. Appropriate seats/decks and/or attachment points for persons can be provided on the main hull 11 and also on the outrigger hull 12 should they be needed. It is expected that a sailor will normally sail the vessel by standing or sitting on the main hull. To assist him in this, a member upstanding from the main hull can be provided with a rail or the like which the user can hold.An outrigger adjacent the main hull can enable the user or users to extend their weight on the side of the main hull remote from the outrigger in an effort to lift the outrigger hull from the water to decrease drag and increase performance. It will be appreciated that in order to change tack it is simply necessary to alter the tension in the cables 16 and 17 in the desired direction. As the boat loses way the sheets 26, 25 are respectively slackened or tightened which transfers the sail from the right of the mast to the left as seen in Fig. 4. Of course, the other characteristics of the vessel must be altered to suit the new course and wind conditions encountered on the alternative tack. 0/03912

-19- Miscellaneous

The vessel has several characteristics which have not been discussed in detail in relation to the above and these will be discussed in the following. _ς The centre of pressure of the sail in relation to the centre of gravity of the main hull can be changed by either warping the cross beams to change the longitudinal position of the two hulls or by warping the mast to place the centre of pressure of the sail . _n forward or aft of the centre of gravity. The centre of pressure in relation to the beamwise centre of gravity of the vessel can be changed by canting the wing sail as described above.

The profiles of the main hull and the wing mast ₁₅ canbe changed to suit particular conditions, that is to say selected ones of the tubes or other containers can be deflated or inflated, wholly or partially or simply varied in pressure to increase or decrease leeward resistance of the main hull's lower tube _?n assemblies.

Inflation and deflation of the various components of the hulls can be effected by manually operated valves at a control position of the vessel. A supply of air for reinflating a deflated tube can be -₅ constituted by the main tube assembly of the main hull, or a separate gas cylinder can be carried. The beams 13 and the remaining member tubes of the hulls 11 and 12 can be connected together to be mutually inflated to the same pressure. This facilitates initial inflation of the vessel.

The tube 39 in the sail wing 14 can be pressurised more than is necessary to be so as to give it enhanced rigidity to act as a spine, or to act as a source of air for tubes 44 and 45 which can be inflated or deflated according to conditions and the amount of mast warping which is required. If and when the outrigger hull 11 is lifted clear from the water the main hull, having its highly inflated lower tubes 30, 31, 32 can act as a planing hull rather than a profile hull and this can give much reduced drag on a broad reach or when running. This ability to act as a planing hull is enhanced by the high pressure within the main hull which can be 200 psi ( ) or more. This would cause the hull to keep its shape even when travelling fast unlike conventional inflatables which distort. Fig. 20 shows the main hull 11 "digging into" the water and resisting leeward drift because of the cavity 33 when used with the warp mast giving a degree of lift. It will be appreciated that the vessel will only achieve this configuration when the crew leans to windward or more aerodynamic forces are applied by the sail to counterbalance the weight of the outrigger boom and sail.

Figs. 26 to 32 illustrate the use of a device known as a HAPA ( HAPA (a type of sea anchor) . The HAPA 50 is attached to the top of the outrigger hull 12 at position 51 and is attached thereto by a line 52 which connects with a twin line harness 53 which connects with top and bottom extremities of a part-cylindrical or comparably curved body 54. The body 54 has an integral or connected vertical vane 55, a horizontal boom 56 and a horizontal tail vane 57. The HAPA acts in many ways like a sea anchor in that the natural leeway of the vessel draws the line 52 tight and exerts a force on the outrigger hull 12 whose direction and effect depends on the position of the attachment point 51. This position can be movable by the user if desired. The two vanes and the boom serve to hold the HAPA in position extending at right angles to the direction of the leeway and the tension on the line 52 exerts a turning force on the hull 12 helping to steer the boat. Under certain circumstances the HAPA can serve to steady the vessel and cause it to keep to a course. Instead of having its position of attachment movable, the attachment point 51 can be fixed and the HAPA itself can be moved relative to its fixing position to vary its position of action and the degree of influence its position has on the centre of pressure relative to the centre of gravity of the vessel. This can be done automatically by providing stop 53a_ one on each side of a swivel 51a so that the angle of attack of the HAPA changes in response to speed, and thence the HAPA changes its position in relation to the main hull. It will be appreciated that as the mast is canted forward or sternwards of its normal position this also will alter the centre of pressure of the sail relative to the centre of gravity, these changes can be used to alter the direction of sailing of the vessel or its sailing characteristics.

The profiles of the main hull, the outrigger hull and the wing mast can be changed to suit particular conditions, that is selected ones of the component tube assemblies can be wholly or partially deflated or increasingly inflated to increase or decrease leewards resistance of the main hull on the lower three tubes, or the tubes of the outrigger hull.

Although the cross tubes 13 have been shown separate from and lying above the various tubes of the hulls, it is possible for them to be integrally joined at T-junctions and be wholly connected to form a single inflatable chamber, or to be connected via valves which allow inflation from a common point, but in the event of puncturing of a single chamber prevent draining of the remaining chambers into that chamber. In the sail part 44 the tube 39 can be over-inflated, for example up to 100 or 200 psi so that it can serve as a reservoir. When tubes 44 and 45 are cyclically deflated and inflated, deflation of each can be effected by opening a valve to atmosphere, and inflation can be effected by opening a valve to the tubes 39. Because tubes 45 and 44 are small and at low pressure repelling thereof from the tube 39 can be effected many times without significant reduction of pressure in 39.

At the trailing edge of the portion 14, where two ends of the outer envelope 48 meet, these two ends can be used to attach the flap sail part 15. Two edge portions of the envelope 48 can be provided with touch- and-close fastener and a leading edge of the flap can have comparable material on both sides and be sandwiched between the two edge portions of the envelope 48. This facility can enable sails of different sizes to be attached quickly and easily to suit different wind conditions.

Being of inflatable construction the entire vessel can be packed, when deflated, into a very small space. The vessel can, in fact, be packed small enough to fit into the boot of a car or a large holdall for transportation to sailing locations. The only bulky and incompressible items are the mast swivel (not shown in detail) and the necessary winches, pulleys, cleats, ropes etc. Here it should be noted that the actual structure of the necessary winches has not been shown in the drawings in order to improve clarity. However, it will be understood by those skilled in the trade that many appropriate winches are currently used on vessels of all kinds.

Of course, the invention is not limited to the precise details of the foregoing, and variations can be made thereto. The idea of altering the pressure of a sail by altering the relative longitudinal positions of a pair of hulls is applicable not only to an inflatable vessel but also to vessels having a pair of rigid hulls or perhaps one rigid hull and one inflatable hull. In comparable manner, the inflatable sail and its two-part construction can also be applied to vessels which are not entirely of an inflatable construction. The outrigger hull can be only a single tube of the diameter of envelope 37. When any component of the vessel is in the form of a plurality of inflatable chambers within an embracing envelope, it is desirable that the internal structure is fully connected together, and that outer parts of the structure is connected to the envelope, as by laminating. This helps to reduce the possibility of creases within the port defining pockets which, during inflation, can be over-pressurised with the attendent risk of damage. Many other variations are possible within the scope of the invention.

Claims

1. A sailing vessel including a pair of elongate hulls connected together, a sail and means for effecting relative forward/aft movement between the hulls.

2. A vessel having an upstanding sail, wherein the sail includes an inflatable mast body and a sail portion.

3. A vessel wherein the sail portion is a flap. 4. A vessel wherein the sail portion is an inflatable structure.

5. A vessel having a sail including a mast portion,the mast portion being mounted and/or constructed so that its upper end can be moved relative to its lower end.

6. A vessel as claimed in any of claims 1 to 5 wherein the sail upstands from one of the hulls.

7. A vessel as claimed in any of claims 1 to 6, wherein the sail upstands from structure connecting (the) two hulls.

8. A vessel as claimed in any of claims 1 to 7, wherein relative movement between the hulls can be such as to move the centre of pressure of the sail forward and aft relative to a centre of gravity of the vessel. 9. A vessel as claimed in any of claims 1 to 8, wherein the hulls are connected by arms.

10. A vessel as claimed in claim 9 wherein the arms are flexible. il. A vessel as claimed in claim 10, wherein the arms are in the form of rigid links pivoted to allow movement in a horizontal plane.

12. A vessel as claimed in claim 10, wherein the arms are additionally constructed or arranged to allow bending in the vertical plane to allow the separation between the two hulls to be varied.

13. A vessel as claimed in claim 10, wherein the interconnecting arms are in the form of pivoted levers or in the form of a lazy tong mechanism. 14. A vessel as claimed in any of claims 1 to 8, wherein the means interconnecting the hulls is in the form of inflatable tubes.

15. A vessel as claimed in any of claims 1 to 8, or 9, wherein one or more guys are connected to the tubes and the hulls and arranged to be tensioned and/or slackened to control bending of the tubes to determine longitudinal relative movement between the hulls.

16. A vessel as claimed in claim 14, wherein the tubes are capable of being arched transversely of the hulls to give sea clearance to the tubes.

17. A vessel as claimed in claim 15, wherein winches control the guys.

18. A vessel as claimed in claim 1, wherein the_ hulls consist of a main hull and an outrigger hull.

19. A vessel as claimed in claim 18, wherein the ail is on the main hull.

20. A vessel as claimed in claim 18, wherein the sail is on the outrigger hull.

21. A vessel as claimed in any of claims 18, 19 or 20, wherein the main or outrigger hull has a cross-section which presents a flat or concave submerged face to leeward of the vessel. 22. A vessel as claimed in any of claims 18 to .21, wherein each hull is of inflatable construction. 23. A vessel as claimed in claim 22, wherein each hull consists of a plurality of adjacent inflatable tubes. 24. A vessel as claimed in claim 23, wherein the tubes are surrounded by an outer envelope.

25. A vessel as claimed in claim 23 or 24, wherein selected tubes are connected, at lines of contact, as by adhesion sewing together or by touch-and-close fasteners such as those sold under the Registered Trade Mark VELCRO or CRIC-CRAC.

26. A vessel as claimed in any of claims 23 to 25 wherein each tube assembly consists of an air impermeable inflatable inner bag in conjunction with an outer layer of tough non-extensible wear resistant material .

27. A vessel as claimed in claim 24, wherein the outer covering is covered by a further resilient expansible covering.

28. A vessel as claimed in claim 26 or 27, wherein the inner air-impermeable material is laminated to the external reinforcing material by means of a flexible and extensible connecting adhesive.

29. A vessel as claimed in claim 2,3 or 4 wherein the sail consists of a body and said flap.

30. A vessel as claimed in claim 29, wherein the flap is continuously attached to the body. 31. A vessel as claimed in claim 29, wherein the flap is connected at spaced intervals to create a slot effect between the flap and the mast body.

32. A vessel as claimed in any of claims 29, 30 or

31. wherein the mast body consists of a plurality of adjacent inflatable tubes.

33. A vessel as claimed in claim 32, wherein the tubes are disposed within a surrounding envelope.

34. A vessel as claimed in claim 32 or 33, wherein one or each tube of the mast body can have its pressure arranged to be variable in use so as to alter aerodynamic characteristics of the mast portion to suit different conditions.

35 A vessel as claimed in claim 34, wherein the structure of the mast portion is such that it is alterable from a profile which suits a port tack to a configuration which supports a starboard tack, or other condition.

36. A vessel as claimed in any of claims 29 to 35, wherein the mast is arranged to be rotatable in order that the vessel can sail in each direction.

37. A vessel as claimed in any of claims 29 to 36, wherein each hull is symmetrical in plan in order that the vessel can sail in either direction in the manner of a proa.

38. A vessel as claimed in claim 34, wherein the mast structure contains port and starboard laterally extending tubes, such tubes themselves being pressure variable in order to allow bending of the mast from port to starboard to take up a curved configuration under certain conditions.

39. A vessel as claimed any of claims 34 to 38, wherein variations can be made in fore/aft tubes within the mast body to allow the mast to curve forwardly or rearwardly.

40. A vessel as claimed in any of claims 34, 38 or 39, wherein movement of the mast head can be controlled both by bending the mast and by tilting the whole axis of the mast relative to a mounting.

41. A vessel as claimed in any of claims 29 to 40, wherein the mast body has a leading edge and a tailing edge, the trailing edge merging towards said flap and the leading edge being bulbous in cross-section. 42. A vessel as claimed in any of claims 29 to 41, wherein the flap is in the form of a simple sheet of inextensible flexible material. 43. A vessel as claimed in any of claims 29 to 41 wherein the flap is in the form of an inflatable flexible thin wedge.

44. A vessel as claimed in any of claims 32,33 or 34, wherein flexing and/or tilting of the mast can be effected by guys connecting the mast to its mounting hull or to other structure of the vessel.

45. A vessel as claimed in claim 44, wherein the guys can be operated by winches.

46. A vessel as claimed in claim 23, wherein each hull has a selected one or ones of its tubes separately and independently increased or decreased in its internal pressure at the will of a sailor to alter characteristics of that hull to suit certain conditions. 47. A vessel as claimed in claim 46, wherein pressure reduction can be effected by operation of a valve.

48. A vessel as claimed in claim 46 or 47, wherein increased pressurisation can be effected by allowing air to enter from a reservoir, or by use of a pump.

49. A vessel as claimed in claim 48, wherein the reservoir is a container of compressed gas carried on the vessel.

50. A vessel as claimed in claim 49, wherein the container of compressed gas is one of the tubes.

51. A vessel as claimed in claim 50, wherein said one tube is a major component of the main hull and is inflated to higher pressure than other tubes to serve both as a reservoir and to give enhanced rigidity to the main hull.

52. A vessel as claimed in claim 51, wherein said pressure is from 100 to 200 psi (6895 to 13790 Nm^" ) . 53. A vessel including a plurality of hulls, each hull consisting of a plurality of inflatable chambers, at least some of those chambers being interconnected by means of touch-and-close fasteners.

54. A vessel as claimed in claim 53, wherein the fasteners are those sold under the Trade Marks VELCRO or CRIC-CRAC.

55. A vessel as claimed in claim 53 or 54, wherein the chambers include tubes arranged to lie side-by-side and be connected as contact by adhesive and or said touch-and-close fasteners where they meet.

56. A sailing vessel substantially as hereinbefore described with reference to the accompanying drawings.