This invention relates to sailing vessels. For many years attempts have been made to improve the sailing efficiency of yachts in order to increase their sailing speed while retaining safety and ease of handling. Catamarans have become extremely popular due to their stability and high speed sailing ability. This high speed potential is achieved by the use of narrow hulls which do not have a displacement speed limitation and by the relatively high power to weight, ratio which may be achieved because of the inherent stability of the catamaran configuration. The power to drive such vessels is derived from sails set fore and aft. It has been realised for many years that the force produced by the sails includes a driving component which moves the boat forward and a lateral component which normally causes the boat to heel and move sideways and that the efficiency of a yacht may be increased by inclining the sails so as to utilize -t e lateral component for producing lift and for reducing the sideways component.

To date however the only commercially successful yachts to utilize sails inclined to produce lift have been sailboards. Inclined sails have also been used on high speed craft such as proas which are reversible twin hulled boats which maintain their respective hulls always in a selected windward/leeward configuration. These arrangements have been used on specialised racing craft only and have not been suitable for general purpose yachts due to practical disadvantages.

Conventional proas have a main or heavy hull and an outrigger or light hull whereby the centre of gravity of the yacht is offset towards either the windward or leeward hull of the craft. In the first mentioned configuration the relatively heavy windward hull gives increased stability provided the vessel is maintained with its heavy hull to windward. If the light hull is positioned to windward the ability of the vessel to stand up to the sail force is greatly

reduced making a capsize probable. In the second mentioned type of proas the overturning moment created by the sail force is resisted by varying the weight of the windward hull, generally either by placing crew on the windward outrigger or by ballasting the latter with water. Such arrangements require an agile crew and are not inherently safe. Thus conventional proas require skilful handling and are not suitable for non-experts.

This invention aims to alleviate the above and other disadvantages and to provide sailing vessels which will be reliable in use. Other objects and advantages of this invention will hereinafter become apparent.

With the foregoing and other objects in view, this invention in one aspect resides broadly in a sailing vessel having a pair of spaced hulls, an inclined sail assembly having its lower part supported by or adjacent one hull and extending upwardly and across towards the other hull. The sail assembly may be a wing sail but preferably the sail assembly includes a ^' sail supported on a stay assembly or the like which extends from a lower attachment position on or adjacent said one hull to an elevated attachment position on a fixed mast above said other hull. The mast may be inclined such that the elevated sail assembly attachment position is either inboard or outboard of said other hull. The sail assembly may include a stay which may be constituted by or incorporated in the leading edge of a sail but preferably it is separate from the sail whereby the latter may be raised and lowered along or furled about the stay. Of course' more than one mast may be used and more than one sail may be set from each mast.

Preferably the mast which provides the elevated support for the sails has its base mounted between the hulls and its top positioned above the outerside of the vessel. This maintains maximum inclination of the sails or stays while enabling all or most of the rigging stays or members to be

maintained substantially within the outermost extremities of the vessel. The sail assembly may be inclined at between twenty to forty degrees to the vertical but preferably it is inclined at between twenty five and thirty five degrees. Of course the masthead could be outside the extremities of the vessel if desired. Suitably the mast is inclined in the athwart plane whereby the staying angles for lateral stays to both sides of the vessel are sufficiently large to eliminate the need for mast/stay spreaders. The stay extending from the outermost side of the vessel to the elevated attachment point may be substantially vertical. Of course a conventionally stayed mast system could be used and the uppermost attachment point could be inboard of the outer extremities of the vessel. In one form ther.e may be provided a central stay or member for supporting a central sail and longitudinally spaced stays or members for supporting respective headsails at opposite ends of the vessel. Either headsail may be employed as required and the central sail may pivot about the central stay for changing direction,. Alternatively a single headsail could be swapped from end to end to suit the direction of travel of the vessel. For this purpose the sail could be in the form of a triangular sail or a spinnaker like sail set flying and adapted to be moved towards either end, such as in a so called "Taylor Rig" . Preferably however the sail assembly includes one or more sails each of which in use is set between upper and lower attachment points about which the sail may pivot for reversal. Such arrangement has the advantage that movement of the sail about its pivot axis to an opposed- position causes the vessel to pivot towards its new heading so that as the sail is sheeted in, the vessel will move off in the desired direction. The line or axis interconnecting the sail attachment points preferably lies between the front and rear edges of the sail. Suitably this axis lies in the front one third of the sail such that the latter in use is substantially balanced.

In a further aspect of this invention there is provided a sail supporting configuration wherein the normal working sails are set as defined above and wherein a storm or strong wind sail assembly is set from a lower elevated position on the mast whereby its lateral inclination is greater than the inclination of the normal working sails such that the lateral force of a sail or sails set therefrom has a reduced or small overturning effect compared to the same force from the working sails. This overturning force is reduced

1 0 irrespective of which hull of the vessel is to windward.

The storm sail may be arranged so that athwartship component of the sail force vector acts through or adjacent the centre of gravity of the vessel so as to substantially reduce or eliminate the transverse overturning moment which

15 may be created thereby. Of course the sail force may be arranged to act through a point at either side of the centre of gravity of the vessel.

This invention in a further aspect includes a steering system for a vessel including longitudinally spaced

20 rudders each being ^" freely rotatable so as to align with the water flow there past and having control means such that they may be used to steer and/or trim the vessel. The operative leading rudder may be locked in a position in which it has a negative angle of attack with the water flow to counteract

" imbalance caused by the sails or asymmetrical hulls and the trailing rudder may be used to steer the vessel or vice versa. Alternatively both rudders may be used to steer the vessel and for this purpose they may be controlled by respective tillers or wheels supported adjacent one another. Preferably however

^J 0 both rudders are controlled for simultaneous actuation by a common steering wheel.

In a proa the rudders may be in either hull and a single rudder could be used, acting as a trailing rudder during motion in one direction and a leading rudder in the

35 opposite direction of motion. Alternatively the rudder or

rudders could be in the form of an adjustable trim board adapted to be raised or lowered or pivoted to achieve the desired balance on any selected heading.

Preferably in larger proas having accommodation, the windward hull is relatively large to provide the accommodation and the leeward hull is in the form of a stabilizing float or outrigger. The float may be assymetrical in plan view so as to create a lift to windward to counteract the drag effects of the float/hull configuration. The outer face of the float may be substantially flat and the inner side of the float may be of similar shape to the corresponding side of the main hull. Thus for fibreglass construction, a half mould may be made of one side of the main hull. Two sides may be moulded from this mould and joined together in side by side relationship to form a main hull and another side may be formed if desired for use as the innerside portion of the float, the outer side being enclosed by a substantially flat sheet or sheets of suitable material. Such a construction method can also be used for timber or any desired form of construction. ϊf desired the balancing forces created by the assymetrical hull could be provided by suitable foils which could be assymetrical if desired. The main hull could be in the form of a displacement or planing hull and the foils could be arranged to lift the outrigger from the water at a selected speed. The foils could be used to steer the vessel.

In order that" this invention may be more readily understood and put into practical effect, reference will now be made to a preferred embodiment of the invention illustrated in the accompanying drawings, wherein: - FIG 1 is a diagrammatic end view of a conventional proa;

FIG 2 is a diagrammatic end view of a proa made in accordance with one aspect of this invention; FIG 3 is a perspective view of a proa according to this invention;

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FIG is a perspective view of a proa corresponding to FIG 3 and illustrating basic rigging details, and FIG 5 illustrates the rudder configuration. Referring to FIG 1 it will be seen that in a conventional proa 10 the sideways force from the sails 11 is horizontal and acts at a distance La from the centre of gravity of the vessel. Thus an overturning moment equal to F.La is produced in use. When acting clockwise this can be counteracted by the leverage exerted by the main hull 12. 0 When acting anticlockwise this can be counteracted only by the leverage exerted by the float 13. Since the main hull 12 may be four or more times the weight of the float 13 it will be seen that it is important that the main hull 12 is maintained to windward for maximum stability. 5 in the proa 14 illustrated in FIG 2 the same force F from the sails 15 acts in a direction inclined to the horizontal so that the overturning moment created thereby is reduced by the smaller leverage distance L from the centre of gravity. The ratio of L:La in this instance, for similar 0 sails is approximately 2.5:1. Since the stability provided by the hulls is unchanged it will be seen that the force F necessary to capsize the proa 14 in either direction will be 2.5 times that necessary to capsize the conventional proa 10. This is particularly significant for a capsizing moment in the 5 anticlockwise direction whereby the risk of capsizing the proa 14 in the anticlockwise direction is greatly reduced.

If high winds are encountered a storm sail (shown in dotted outline at 16) may be set on a lower stay 17, or free if desired, such that the sail inclination is increased ° whereby its force Fs acts through the centre of gravity thereby producing no overturning moment due to wind pressure. If desired the storm sail 16 could be set with the outer sails which could be lowered during periods of strong winds or when sailing with the vessel unattended. ⁵ In the vessel 20 illustrated in FIGS 3 and 4, the

working sails are inclined at thirty degrees to the vertical and comprise a pair of identical balanced triangular sails 22 each having their upper ends supported pivotally by a mast 23 and their respective lower corners 24 and 25 supported adjustably in spaced apart relationship by a boom or batten 26 which is anchored pivotally to the outrigger 27 at positions 28 approximately one third back from the leading edge of each sail 22. The trailing ends 29 of the booms 26 are interconnected by a strut 30 and control ropes 31 lead from the strut 30 about blocks 32 at the respective opposite ends of the outrigger 27 to the cockpit 36 so that the sails may be trimmed and rotated through 180 degrees to enable the vessel 20 to sail in opposite directions of travel. For this purpose the aft line 31 is adjusted to pivot the sails to their operative positions.

Trim lines 33 may be connected between the leading ends of the booms 26 and the bridgedeck 34 (which connects the outrigger 27 to the mainhull 35) to prevent over rotation of the sails beyond their close hauled positions. These trim lines 33 may be adjusted from the cockpit 36. The luff of each sail 22 is hanked to its respective forestay 37 both of which extend from the masthead 38 to the leading end 39 of a boom 26 while, in use, the leech extends freely from the boom 26 to the masthead. Howe-ver, in use the leech will at all times be tensioned so that the sail is maintained in a selected airfoil shape irrespective of its pivotal location. The sails 22 may be raised, lowered and stowed in conventional manner as shown _, in FIG 4. The sails may be set on roller furling gear if desired. The lower part of the sails 22 may extend downwardly from the boom 26 to the anchor positions 28 on the outriggger. Such sails may be set loose from the boom with the leading sail set outside the boom and the trailing sail set inside the boom. This will have the effect of producing a leading sail which will be fuller than the trailing sail.

As shown in FIG 4, each boom 26 is permanently suspended from the masthead 38 by the forestay 37 and a rear stay 40, both of which are pivotally attached to the masthead 38 and each boom 26 is connected pivotally to the outrigger 27 at 28 by a bridle or brace. In this embodiment the bridle has a short leading bar 41 and a longer trailing bar 42 whereby the boom may pivot about the respective axis 43 passing from the masthead through the anchor points 28. Each axis 43 is disposed intermediate the forestay and backstay and the luff and leech of the sails 22 and in the leading part of each sail 22. The booms 26 are interconnected by the strut 30 for simultaneous pivotal movement. The strut 30 may be length adjustable if desired to enable the relative settings of the sails to be varied. The trim lines 33 may also be used for this purpose.

The control ropes 31 may pass to a common winch rotatable in either direction to pivot the sails in a corresponding direction. This winch may include a wheel activated rope drum which may be supported co-axially with a steering wheel 40 for ease Of control of the vessel 8. ^■ > Alternatively the rope 31 may pass to separate winches. The clew 25 of one of the sails 22 may be attached to its boom 26 by a trip mechanism adapted to release when the sail is caught aback. In such situations release of one sail will halve the sail force. Wind force on the other sail will force the vessel back around to its correct alignment.

In the embodiment illustrated there are provided two rudders 46 and 47 disposed one at each end of the outrigger 27. Each rudder is a freely rotatable balanced rudder which rotates through 180 degrees when the vessel 20 reverses.

These rudders 46 and 47 are steered from a common wheel. Each is provided with a foil 49 at its base. The rudders 46 and 47 are pivotable about inclined axes 50 as illustrated in FIG 5, and the blade of each foil 49 is inclined to its axis of rotation so that the angle of attack of the leading rudder is

always greater than the trailing rudder. In use this lifts the bow of the outrigger 27 and stabilizes the stern. The stern rudder remains submerged for steering. The foils 49 also form end plates on the rudders whereby relatively shallow rudders can be used to effectively control the vessel.

The outrigger 27 and the mainhull may be provided with a keel which may be assymetrical in plan view if desired. Preferably however the main hull is of shallow form so that it will slide sideways through the water should the vessel be caught in strong winds with the outrigger 27 to windward. In such event, if the vessel begins to overturn, the sail will quickly approach a horizontal attitude and spill the wind therefrom. A lee-board or daggerboard 51 or the like may be positioned centrally on the outrigger 27.

In lieu of the two sails illustrated a single balanced sail of the type described above could be used. This could be an assymetrical sail which would be rotated about a cen-tral pivot point on the outrigger for reversing or it could be a symmetrical sail having a boom mounted track connected by a traveller car to a central position of the float 14 whereby the pivot axis of the sail could be varied as desired, suitably by tensioning respective sheets connected to the lower corners of the sail at opposite ends of the boom.

Other vessels provided with a centrally, disposed mast could also utilize the sails of this invention. For example on a catamaran a storm sail could be set between a float and a suitable position on the central mast. Alternatively the vessel could be provided with respective sets of sails set on inclined stays or spars at each side for use on respective tacks. Furthermore the balanced sail assemblies described herein could be used advantageously on a conventional proa or other sailing vessel with upright sails by utilizing a bipod mast assembly with the balanced sail set between the legs of the mast assembly and such configurations are embraced by this invention.

Of course it will be realised that the above has been given only by way of illustrative examples of the present invention and that all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is defined in the appended claims.