"SAILING VESSELS" This invention relates to improvements to proas of the general type illustrated in PCT/AU 86/00159 and adapted to sail with either a light hull or heavy hull to windward. The proas illustrated in the abovementioned application utilised a sail supporting arrangement which imparted a high bending moment to the cross beams or deck assembly interconnecting the main hull to the float. While they have proved satisfactory and capable in use, the necessity of manufacturing such strong decks increases the weight of the vessel and their complexity of construction. It is also difficult to form effective end connections for such decks where they are to be dismantled or folded for trailing purposes. This invention aims to alleviate such disadvantages and to provide proa sailing vessels and construction methods which will be reliable and efficient in use. Other objects and advantages of this invention will become apparent from the following description. With the foregoing and other objects in view, this invention in one aspect resides broadly in a proa including:- decking supported by a pair of spaced hulls comprising a windward hull and a leeward hull, each of the latter having respective underwater sections which are substantially symmetrical about a transverse centreline; a mast assembly including a mast fixed to a base beam

having a sail outhaul whereby a sail supported by or attached to sail mast may be maintained in an selected tensioned configuration; upper supporting means for supporting the upper end portion of said mast substantially within a vertical projection of said windward hull; lower supporting means disposed substantially within a vertical projection of said leeward hull for supporting said base beam for pivotal movement about an inclined axis extending between said lower supporting means and said upper supporting means whereby said base beam may be pivoted about said inclined axis; elevated sail holding means associated with said upper end portion for holding the upper portion of a sail; lower sail holding means associated with said lower end portion for holding the lower portion of a sail; sail hoisting means for hoisting a sail to extend between said elevated and lower sail holding means, and control means for controlling the pivotal movement of said base beam about said inclined axis.

The sail assembly may be adjustably inclined and preferably between twenty and forty-five degrees to the vertical. Of course the masthead or the mast or sail base could be outside the extremities of the vessel if desired. The line or axis interconnecting the sail attachment

points preferably lies between the front and rear edges of the sail which may constitute an assembly of sails comprising a fore sail and a main sail. Suitably this axis lies in the front one third of the sail such that the latter in use is substantially balanced or balanced to a significant extent whereby loads on the control means are significantly reduced. This is particularly advantageous when pivoting the sail between windward tacks when the proa is substantially stationary, as the pivoting of the tensioned sail causes opposed pivoting of the proa from the old heading to the new heading.

The mast may be secured to a base beam which projects forwardly therefrom to support a headstay or sail and rearwardly to support the outhaul for the clew of the sail set from the mast. Back stays for tensioning the luff or headstay may also extend from the mast to the rear of the base beam. In this manner sail tension stresses are accommodated internally within the mast and base beam and as a consequence, the decking between the hulls may be relatively light.

Suitably the upper end portion of the mast is supported by prop means which connects pivotally to the front of the mast, and above the forestay connection if a forestay is used. The prop means may be stayed to enable controlled fore and aft movement of the upper end of the mast and it may be extendible or otherwise mounted to enable the inclination of

the mast to be varied.

In another aspect, this invention resides broadly in a method of building a boat hull, the method comprising forming hull side panels having mating end parts formed with a curve extending between the upper and lower edges of the hull side panels and having a longitudinally outermost point medially therebetween; arranging said panels congruently; securing the mating front end parts together, and moving the upper edges of the side panels apart so as to induce transverse bowing of the side panels.

The bottom edges of the side panels may be connected together or a bottom panel may be interposed therebetween. The hull side panels may be symmetrical about a transverse centreline or one end of the side panes may be interconnected through a transom panel. Preferably the side panels are formed of plywood, but of course the side panels may be formed of any suitable material such as fiberglass reinforced plastics material or the like.

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 perspective view of a typical proa according to this invention; FIG. 2 and 3 are front and plan views illustrating a further embodiment of this invention;

FIG 4 is a perspective view illustrating the configuration of each rudder of the proa illustrated in FIG 2; and FIG. 5 is a perspective view of the hull panels for the main hull illustrated in FIGS. 2 and 3; FIG 6 illustrates a typical building jig.

The proa 10 illustrated in Fig 10 utilises an internally stressed sail assembly 11 whereby mast stay tensions are reacted against the mast 12 and the base beam 13 and thus do not induce high bending moments in the cross beams or deck 14. A relatively light proa can therefore be given a relatively wide beam and a relatively large sail assembly 11. The mast 12 is supported by rigging which includes a prop 15 stayed by stays 16 which may be fixed or running to enable the prop 15 and the mast 12 to be pivoted fore and aft. The mast 12 is supported rotatably on the base beam 13 which is connected universally at 17 to the float deck 18. A forestay 19 and opposed side stays 20 secure the mast to the base beam 15. The prop 15 connects to the front of the mast 12 above the stays 19 and 20 by a universal mounting 22. The prop 15 is a telescopic strut which may be selectively extended or retracted to vary the inclination of the sails and thus maintain them at maximum driving inclination.

The float 23 is tubular and the end sections 24 are supported on central tubular stub axles 25 which pass through bearing tubes 26 fixed to the float 23 so that they may be

rotated about a longitudinal axis 28 to pivot the end sections 24 and thus the steerable foils 27 about the axis 26, as required. The rudders 27 are steered through right angle drive gearboxes 31 by steering controls 32 which pass through the hollow stub axles 25 and the cross beams 14 to the main hull 35. Further control cables pass around the exposed end portions 37 of the stub-axles 25 and through the cross arms 14 to the cockpit to enable rotation of the end portions 24 and thus the inclination of the rudders 27 and their projected vertical area to be selectively varied. In use, the centre of pressure of the sails will be behind the centreline of the vessel. Accordingly, the centre of lateral resistance can be varied fore and aft by varying the relative athwartship inclinations of the rudders. For example, the leading rudder can be inclined at 45 degrees while the trailing rudder remains vertical. The latter can be used for steering and the leading rudder trimmed to create lift to counteract sail forces which tend to depress the leading end of the proa 10. The sail assembly 11 can also be trimmed fore and aft so that both leading and trailing rudders are operated to provide lift to windward.

In this embodiment, the sail assembly 11 with the base beam 13 is pivoted about the axis extending between the deck mounting 17 and the prop mounting 22 to position the sail assembly 11 for use in either direction and to turn the proa from one windward heading to the other. Front and rear

control lines 41 and 42 are provided for this purpose. The sails 43 and 44 may be adjusted in conventional manner.

A solid wing can also provide such benefits. Preferably the latter is pivoted from a base point aft of its leading edge so that the sail will be partially balanced to reduce control forces. Furthermore the sail assemblies described above can be pivoted so as to be overbalanced if desired.

The proa 50 illustrated in Figs. 2 to 5 differs from the previous embodiment principally in that the deck assembly 51 includes folding cross beams 52 whereby the overall width of the proa 50 may be reduced and in that the mast 53 is mounted at the front of the base beam 54 whereby a single working sail 55 is utilized. This arrangement permits the mast to be swung to a position adjacent the vessels cockpit to provide ready access to the mast for sail hoisting or reefing purposes.

Off wind sails such as spinnakers and reachers may be set, preferably from a halyard 56 exiting the mast 53 below the connection 57 between the mast 53 and the supporting prop 58. This arrangement permits the off wind sails to remain hoisted during a jibe when the off wind sails may pass beneath the prop 58. A pole 59 for the off wind sails may be supported on the mast as illustrated.

As illustrated, the connection between the mast 53 and the base beam 54 includes a pair of struts 60 which extend from connections at opposite sides of the base beam 54 to

respective connections at opposite sides of the mast 53. If desired the mast may be rotatably connected to the front end of the base beam 54 and to the upper ends of the struts 60 to enable the mast to rotate about a longitudinal axis independent of the base beam 54. A compression strut 62 and associated stay 63 may be used to spread the strut loads along the mast.

The sail 55 is hoisted along a mast groove 61 by a halyard 63 and its tack is secured to the base mounting 64. Preferably the base beam 54 is hollow to form a receptacle for the lowered sail 55. In Figs. 2 and 3, the base beam is illustrated in its athwartship position. It can be pivoted by respective control lines 65 to a selected fore and aft attitude at either side of the position illustrated. The float 70 is connected to the main hull 71 by the cross beams 52. The latter are bolted at 73 to the side walls 74 of an integral pod 75 which extends centrally from the main hull 71. The outer ends of the beams 52 carry vertically disposed tubular sockets 76 which engage rotatably about posts 77. Guide frames 78 nest between the upper and lower members 79 of the beams 52. Their outer ends 80 connect pivotally to members 79 while their inner ends connect pivotally at 81 to the side walls 74. Thus the guide frames 78 may pivot about their respective side wall mountings 81 from a stowed position within the cross beams 52 when the latter are extended as shown, to a folded position

at which their outer ends 80 support the cross arms 52 in a retracted position as illustrated in dotted outline.

Lateral resistance and steerage is provided by a pair of identical dagger assemblies 80 as illustrated in Fig. 4 which are supported in cases at the ends of the float 70. Each dagger assembly 80 includes a symmetrical flat sided foil 81 supporting a rudder stock 82 which extends rotatably therethrough. The rudder stock supports a conventional spade rudder 83 and carries a steering wheel 84 at its upper end. The wheel 84 is connected by cables 85 to respective tillers 86 mounted pivotally at 87, intermediate the cable connections, to the pod 75. The arrangement is such that either or both the front and/or back rudder may be used. Each will automatically align itself in a trailing attitude. Normally with the front rudder trailing freely and the bach rudder held, the centre of lateral resistance will be biassed to the rear to balance sail forces. Preferably the cables 85 are adjusted so that the front tiller is pivoted away from the pod 75 when the front rudder is in a trailing position. The rudder profile is such that it may fit within the confines of a dagger case adapted to accommodate the dagger foil 81 and of course if desired only one foil may be fitted with a rudder if desired.

Referring to Fig 5 it will be seen that the ends of the main hull side panel 90 are curved form the bottom edge 91 to the top edge 92 and that the longitudinally outermost points

93 are intermediate these edges. The main hull 71 is constructed by forming the flat side panels 90, loosely connecting their lower edges 91 to the intermediate side edges of the bottom panel 95 (shown dotted) and their curved front edges 96 together. The top edges are then pulled apart to the desired extent such as is illustrated by the dashed lines 97 and the joins made fast in conventional manner such as by forming with glass tape.

The curved ends 96 induce significant lateral curvature in the side panels 90 which is otherwise difficult to achieve. This curvature forms a desirable underwater shape in the lower portion of the hull and greatly rigidifies the side panels. Thus a relatively lightweight structure can be formed. If desired the hull side panels 90 can be assembled to the bottom panel 95 in an inverted attitude with the bottom panel supported in an elevated position on a central jig and with the side panels supported on opposed pairs of arms pivotally connected to the jig. The side panels are pulled apart by pulling the arms apart. Fig. 6 illustrates a suitable jig for this purpose.

Of course the windward hull or the leeward hull may constitute the heavy hull or the accommodation hull, as desired, depending upon the desired application. 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.