EP0312129A2

EP0312129A2 - Sailing vessel

Info

Publication number: EP0312129A2
Application number: EP88201328A
Authority: EP
Inventors: Jelle Fake Berghoef
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-09-24
Filing date: 1988-06-27
Publication date: 1989-04-19
Also published as: AU1855988A; NL8702287A; EP0312129A3

Abstract

Detachable sailing vessel for high speed and performance comprising a horizontal triangular frame having its apex forward, which is carried by one central frontfloat under the apex and two rear-sidefloats, one under each side corner at the sternbeam.

Stearing is done with a helm at the stern acting on either the frontfloat or on both rear-side floats.

In the latter steering mode, the frontfloat may have automatic course compensation by being able to pivot over about ± 10° while being urged by elastic means into the central position.

The mast is positioned near to the frame-apex and leans back at about 30°. Its both side stays run upwards from the sidebeams at a slight rearward angle of 5°-10° with regard to the vertical to the frame. Said side stays may consist of buckle-stiffened shores.

The vessel has one (main)sail with free (loose) underside.

Description

The invention relates to a sailing vessel with three hull-shaped floats, of which at least two are adjacent and positioned at a distance from and essentially parallel to each other, and comprising in addition a rigid connecting structure between the floats, steering gear connected to a tiller at the stern, a mast with stays, a sail with an adjustable clew connection in the rear underside region to a fixed part of the connecting structure, and a taut net stretched between the connecting structure in the stern area and serving as a working surface for the yachtsmen.
Sailing vessels of the type described above are known from trimarans. These are sailing vessels that are specially designed to be able to reach high speeds. The hulls are slim and there is little or no accommodation for the crew members, they mostly have only a mainsail and the whole structure and shape is designed for high speed and as low a resistance as possible in the water and through the wind. On the smaller vessels the yachtsmen are carried on a taut net serving as a working surface that is fixed between the connecting structure of floats. A comparable type of ship which is intended to reach the greatest possible speed are the catamarans, which have two essentially parallel slim hulls as floats. They also have mostly only one mainsail. One similarity between trimarans and catamarans is the fact that they have to remain purposely as upright as possible during sailing and that the maximum sideways tilt or list remains very small and is determined by the windward float just coming out of the water and the leeward float being pushed deeper into the water, so that the mast has a maximum possible list of about 20° from the vertical.
A disadvantage of the known trimarans and catamarans as far as they fall into the smaller category that can be taken apart and transported by road on a car is the fact that the floats or hulls are relatively large and heavy. In addition, tacking or giving way is difficult and sometimes impossible because of the very slim shape of the long hulls. These vessels have rudders that are placed immediately behind the hulls and are operated simultaneously.
The object of the invention is therefore to provide a sailing vessel of the type mentioned above that does not have the said disadvantages and that is, in particular, easy to disassemble and transport. To this end the sailing vessel is characterized according to the invention in that the third float is positioned as a front float at a fair distance in front of the two adjacent rear floats and on the longitudinal centre line, and in that the plan view of the connecting structure takes the form of an isosceles triangle or isosceles trapezium of which the base forms the stern beam and the equal sides the starboard and the port beams, and the apex or short parallel side forms the junction at the bow, and there being, in the region of the corner joint between the starboard beam and the stern beam, means of attachment to the rear starboard float and similarly on the port side, and in the region of the bow junction for attachment to the front float, and the frame being - when the vessel is ready for sailing - essentially horizontal.
Whereas in trimarans the third float is placed between the two outside floats, according to the invention the third float is positioned on the centre line of the vessel at an appreciable distance in front of the two rear floats and the plan view of the connecting structure forms an isosceles triangle or isosceles trapezium. The longitudinal stability of the vessel according to the invention is thereby considerably greater than that of catamarans while the lateral stability, for comparable width, is roughly similar to that of catamarans. According to a preferred embodiment, the front float is pivotably attached to the frame and is connected to the tiller so that the vessel can be steered by pivoting the front float. Compared with the known trimarans and catamarans with a similar area of sail, the vessel according to the invention has much shorter floats. As a result, inter alia, of this and because of steerability of the front float, giving way in the vessel can be carried out much more easily.
Because the vessel is designed for high speeds, the hulls are shaped in a manner known per se so that they will plane at high speed. Consequently lateral friction with the water is slight, such that a preferred embodiment provides each float with a cutwater or keel beam over essentially the whole underwater length of the float. Per se the leeward rear float will be pushed deep into the water during sailing so that the shape of this hull will also contribute inter alia to the directional stability. The planing front float will, however, get its directional primarily stability from the cutwater or keel beam.
Since the crew take their places at the stern and because the force of the wind in a preferred embodiment of the sail also strikes more to aft, the vertical load on the front float during sailing can be relatively small, for which purpose the front float can be provided with a retractable centreboard. Although it is clear that there is a great freedom of design with regard to the length-to-width ratio of the vessel and hence the frame, it seems to be attractive that in a preferred embodiment the floats have between about 1/3 to 1/4 the length of the connecting frame.
With an eye to simple manufacture, all three floats are essentially alike. The only difference relates to the attachment to the frame, which is of pivotable construction for the front float and rigid and directionally fixed for the rear floats. In addition, as mentioned above, the front float can be provided with a retractable centreboard.
Trials have shown that the controllability, particularly in rough water, can be further improved in that, according to a preferred embodiment, the two rear floats are attached to the frame so that they can pivot around a vertical axis through the attachment point and are connected by linking means, such as steel wires and guide rollers, to the tiller such that they remain essentially parallel to each other at all positions of the rudder.
In addition the directional stability of the vessel when heeling over to a great extent is found to be improved if, according to a further embodiment, the front float is similarly attached to the frame so that it can pivot around a vertical axis through the attachment point and that, for automatic course compenstation when the vessel is heeled over to a great extent, a prestressed elastic component, such as a spring, is positioned between the rear of the front float and both the starboard beam and the port beam, which components always urge the front float into a central position with respect to the vessel, all this such that the front float can make an angle of up to about±10° with respect to the centre line of the frame. In this way the course will be automatically compensated when, if the vessel is heeling over to a great extent, the front float were to have an increasing tendency to plunge itself deeper into the water.
In the embodiment with steerable rear floats, it is advantageous to use longer floats about 0.5 times the length of the frame. Giving way is greatly improved with rear steering as opposed to front steering, such that slimmer and longer floats can be used which have a hull shape which cuts through the water rather than its planes Because inter alia the floats are relatively small compared with the hulls of catamarans and trimarans and have to be able to sail over rough water, they have a completely closed construction and, for reinforcement and for safety, can be completely foam-filled in a known manner with, for example, hard closed-cell polyurethane foam. The same also applies to the aluminium tubes or profiles from which the frame can be constructed, all of which can be similarly foam-filled to achieve additional buoyancy when capsized and through which safety is also improved.
Whereas in the case of similar fast sailing vessels, such as catamarans and trimarans, the mast is mostly positioned near the centre of the vessel's length in order to achieve a favourable pressure point for the forces of the wind with respect to the movement of the hulls through the water, according to a preferred embodiment of the invention the same is achieved in that the foot of the mast is placed in the frame in the region of the bow junction and the mast leans back at an angle of between about 25° and 35° from the vertical, preferably at an angle of about 30°. Consequently the pressure point of the sail lies approximately in the area occupied by the yachtsmen. In addition, this prevents the front float being subject to too great lateral forces so that it can keep well on course and does not tend to veer excessively or uncontrollably to leeward. Although there are vessels which have masts with no stays, it is advantageous and improves the safety to provide the mast with stays. In the vessel according to the invention, this can be achieved extremely well by attaching the usual fore stay to a rigid bowsprit-shaped extension to the frame, while the side stays rise upwards towards the stern from the port and starboard beams of the frame at a slight angle of about 5° to 10° with respect to the frame - seen in side view of the vessel. Consequently the mast is stayed stably in all directions. The advantage of the unusual angle of inclination of the side stays lies in the fact that when running free the sail has enough room to fill out because of the greater backwards inclination of the mast. The usual known steel cables with tensioners can be used for the stays described above.
The bowsprit-shaped extension to the frame described above for the fore stay can, if desired, be avoided if both side stays are replaced by buckle stiffened shores which rise upwards towards the stern at the same slight angle. High demands regarding buckle resistance are placed on these shores. The reason is that both of them are mostly under pressure because the taut clew pulls the sail and the mast backwards. The leeward shore will obviously be most under pressure during sailing. In order to prevent buckling outwards under all conditions it is advantageous to make the shores barrel-shaped, whereby their weight is kept to a minimum. However, in many cases the cost price will be appreciably higher than the classical staying with steel cables as fore and side stays
Just as it is usual to stiffen a mast over its length and especially over the portion not supported by stays, stays run over are used. A similar stiffening can be necessary in certain circumstances in the region of the starboard and port beams at the point where the side stays, either as pulling steel cable or thrusting shore, act. Many constructions will be feasible for this as will be clear to those skilled in the art.
In order to achieve a relatively large sail area for high speed while not using a very high mast and hence achieving a more favourable stability, it is advantageous to place the underside of the sail immediately above the frame. In order to avoid accidents to the crew, which latter cannot duck into a tub or suchlike, the sail is characterized according to the invention by lacking of a rigid boom and by having a free or loose underside. For this purpose the clew is attached to the rear bottom corner of the sail, which point lies nearly in a vertical plane through the stern beam of the frame when the sail is spanned amidships. Consequently the sail is stretched backwards as well as downwards. Because, inter alia, there is no rigid boom, in a preferred embodiment a rail or passage for a guide eye or guide block for the clew is provided and this extends over the whole length (or width) of the stern beam of the frame. As a result the rear underside corner of the sail can be pulled backwards and downwards in the desired direction for all sail positions so that the sail can assume an optimum position with respect to the wind and sailing direction.
In addition, it may be further mentioned that all means of attachment between the frame and the floats are provided with easily detachable structures and that the frame itself is constructed of essentially straight beams and small corner connectors, which are similarly linked together with easily detachable attachment devices, such as mortise and tenon constructions and/or retaining clamps. The vessel can therefore be completely disassembled or assembled in a short space of time. To illustrate the low weight and the dimensions of a suchlike vessel, the following values for a vessel of the model and type as discussed hereafter can be given on the basis of the attached drawings:
- sail area about 22.5 m²
- total length 6.9 m
- total width 3.5 m
- weight of each float 20 kg, for a length of 2.0 m and a width of 0.6 m
- completely submerged with a water displacement of 300 litre.
The total weight including the mast, sail, stays etc. is about 100 kg, the heaviest components weighing 20 kg.
This will be explained as an example on the basis of the following description of the attached drawings of a preferred embodiment of a vessel according to the invention.

Fig. 1 shows a side view of a sailing vessel according to the invention with front steering.
Fig. 2 shows a plan view of the vessel in Fig. 1.
Fig. 3 shows an alternative embodiment of the vessel according to Fig. 1, in which rigid side stays are used and a butterfly sail is hoisted to give a greater sail area for use when there is less wind.
Fig. 4 shows a detail of the pivoting structure of the front float with respect to the frame.
Fig. 5 is a schematic drawing of the one of the possible steering systems.
Fig. 6 shows the vessel according to the invention provided with steering using both rear floats.

1 depicts the complete sailing vessel. The major components are a starboard rear float 2, a port rear float 3, a central front float 4, an connecting frame 5, which is triangular in plan view, a mast with stays 7, a sail 8 and a steering mechanism 9.
The three floats 2,3, and 4 are essentially identical to each other. They have the shape of small ship's hulls of the type that plane at higher speed, so that the hulls consequently have a somewhat V-shaped flat bottom 21, 31, 41. To achieve sufficient displacement of water when submerged to a greater extent, the sides of the hull 22, etc. are virtually vertical, so that the vessel is of the split rib type. To increase directional stability, particularly when the sailing vessel planes at high speeds, all the floats are fitted with a cutwater or keel beam 23 etc. The floats have a closed deck and, for safety and strengthening, are completely foam filled with a hard polyurethane foam with closed cells. Not shown are the ribs known to the person skilled in the art to which two vertical tubular stubs are attached that protrude from above the centre line of the deck. The front tubular stub 24 serves in the front float 4, where it takes the form of the tubular stub 44, as the only means of attachment to the frame 5. This will be elaborated later. The two rear floats 2 and 3 each have a second tubular stub 25, 35 which serves as a second point of attachment to the frame 5. All the floats are therefore completely closed.
Because the front float 4 will easily plane and, as will be described later, serves to steer the sailing vessel, it may be advantageous to provide the front float 4 with a retractable centreboard known per se which is pivotable on a schematically shown hinge pin 47 and can be retracted into a per se known centreboard case (not shown) completely within the hull of the float and on the other hand thrust straight down to improve appreciably the directional stability, particularly during planing, and as a result to prevent veering to leeward.
The three floats 2, 3 and 4 are connected to each other by a single connecting frame 5 which lies approximately in the horizontal plane. This frame 5 is carried above the surface of the water by the floats and is the carrier for the mast with sail as well as the crew or yachtsmen. It is composed, as shown in Fig. 2 in particular, of a starboard beam 51 and a port beam 52 and a stern beam 53. In plane view the frame forms an isosceles triangle or an isosceles trapezium of which the short parallel side near the bow of the vessel is very short. With an eye to easy transportability when dissassembled, the frame 5 is constructed of separate parts. For this purpose the frame 5 is built up of two straight beams 51, 52 which form the starboard and port beams respectively and a separate straight stern beam 53. They are linked together at both corners at the base of the triangle, that is, at the stern beam 53, by separate corner pieces 54. These are attached to the beams in a known manner with, for example, the schematically shown mortise and tenon joints and are secured with clamping bolts. The starboard and port beams 51 and 52 are attached to each other at the bow by two clamping plates which will be described later with Fig 4. In a manner which is not further specified, there is a connecting beam 55 positioned at about 1/3 of the length in front of the stern beam 53 and parallel to it, the means of attachment to the side beams 51 and 52 not being further specified. The connecting beam 55 stiffens on the one hand the frame to a considerable extent because the long starboard and port beams 51 and 52 are strutted against each other, and the connecting beam 55 furthermore forms, together with the stern beam 53 and the rear portions of the side beams 51 and 52, the trapezium-shaped portion of the frame in which the net 56 is strung which serves as a working surface for the yachtsmen in a known manner. As can be seen clearly in Fig. 2, the front attachment stubs 24 and 34 of the rear floats 2 and 3 are attached to the starboard and port beams 51 and 52 respectively by clamps 57 shown schematically, while the rear tubular stubs 25 and 35 are attached close to the ends of the stern beam 53. Consequently it is possible that, despite the triangular form of the frame 5, the two rear floats are nevertheless directed parallel to each other in the direction of sailing and cannot turn with respect to the frame as a result of each being doubly attached. The clamps 57 are also made easily detachable using parts known per se.
The mast 7 is attached at its bottom by means of a bolt joint to the front end of the frame 5 at location 59. The staying of the mast, to be discussed later, obviously has its supporting points on the frame. The rear stays of the mast are attached to the starboard beam 51 at location 57 in a not further specified known manner and similarly at location 58 to the port beam. Since the rear or side stays can exert large forces at locations 57 and 58, which forces are directed essentially perpendicularly to the frame 5 and hence to the frame beams 51 and 52, it may be advantageous to stay the beams at these points with an unspecified means of staying such as, for example, is used for a mast with the aid of a steel cable which is held at a distance by a spreader. In this way a triangle is formed such that the steel cable used is always under tension. Consequently, when upward pulling side stays made of steel cable are used, the strenghtening stays of the side beams 51 and 52 will be constructed with stretchers pointing upwards. If downward pushing side stays are used then the strengthening stretcher of the side beams obviously has to point downwards in a manner known per se. Depending on the stays used, and certainly in the case of stays made of steel cables, a forestay will be used which must be able to be attached in front of the abutment of the mast 7 at location 59 on the frame 5. In the latter case the frame is extended forwards with a bowsprit-shaped extension beam 60. This is also detachably mounted in the front end of the frame 5.
The mast 7 of the vessel according to the invention leans backwards in an unusually steep fashion at an angle of about 30°. This achieves the result that with a reasonably short length of mast, which promotes stability, a relatively large sail area can nevertheless be accommodated for the benefit of the fast speed of the vessel. The mast is provided with an integral mast rail 71 in the usual manner in which the leading edge of the sail can be taken up. The mast can be split at 72 in a manner known per se and not specified further in order to facilitate transport. In a similarly known manner, and in particular when it is split at 72, the mast can be stiffened with the aid of a stretcher 73 and a stay 74. The forestay 75 grips close to the split 72 when the traditional stay construction is chosen with steel cables which hold up the mast in three directions in a statically determined manner. In addition to this both side stays 76 and 77 are then required which stays grip the starboard and port beams 51 and 52 at the locations 57 and 58 respectively already mentioned. In this way the mast is stayed in the usual manner with only one characteristic difference from the masts of known fast sailing vessels, namely the large angle of inclination α to the rear. In order to prevent the billowed out sail from coming into contact with the stays when running free, these stays run upwards in an unusual manner from the points of attachment 57, 58 on the side beams 51, 52 and lean backwards at an angle of 5° to 10°. In this fashion the mast can on the one hand be supported with sufficient safety because the angle between the mast and the various stays remains normal, and on the other hand the necessary room for billowing out of the sail, particularly on the underside, is provided. In order to prevent the vessel from turning completely upside down when capsizing, a float 78 is attached to the top of the mast in the usual manner. Because the sailing vessel according to the invention must be able to sail rapidly and an appreciable to strong wind force is, in general, required for this, sailing will mostly have to be done with one or more of the crew hanging in a trapeze in order to keep the vessel as upright as possible. A suchlike trapeze is attached to the mast with a steel wire 79, shown schematically, at the same point close to the split 72. Trapeze cables are obviously situated in a known manner both on the starboard and on the port side and they can be doubled up if both the helmsman and a crew member use a trapeze.
8 is a schematic representation of the sail through the form of which the pressure point of the wind force will lie roughly above the cross member 55 of the frame 5 so that the the load from the wind and of the crew will be well distributed over both the rear floats and the single front float. In order to keep the centre of gravity as low as possible, the foot 81 of the sail is positioned very low and in fact immediately above the net 56. In order to prevent accidents to the crew with such a low positioning of the foot 81, the foot hangs like so called baggy trousers so that there is no rigid boom. For the desired fast sailing the sail needs to be as flat as possible and for this purpose sail battens 86 are used in a known manner in the sail which battens run with the direction of the wind. In addition the clew 83 has to consequently grip at the rearmost lowest corner 82 of the sail and is shown schematically in the drawing as being triply anchored through the blocks 84 and 85. In Fig. 1 the sail is drawn in the centre position in which obviously no sailing is done. If the sail is positioned some way out to port or starboard when sailing close to the wind, then the corner of the sail 82 deviates not only across but also forwards, so that the direction in which the clew 83 acts on the sail is directed more to the rear, so that the lower part 81 can be pulled appreciably straight. Because of the lacking of inter alia a boom, the block 85 will have to be able to slide with the aid of a guide eye or guide block, which is shown schematically, along a guide rail or run-over 62 which extends over the whole length or width of the stern beam 53. Per se known structures can be used for this, although for the vessel according to the invention the length of the guide rail or run-over is appreciably greater than for known vessels.
As a result of the lower part 81 of the sail being pulled very far down, the latter is provided with windows 87 in a known manner so that the view of the yachtsmen is hampered as little as possible.
Fig. 3 shows schematically a similar vessel to that in Fig. 1 and 2. This diagram, however, illustrates in which way the sail can be enlarged by about one quarter or one third of the area so that sufficiently fast sailing is possible even in less strong wind. For this purpose a butterfly sail known per se is used, of which the curved upper part of the trailing edge is held in the correct position by one or more additional sail battens 88, of which one is shown. In addition in Fig. 3 an alternative embodiment of the staying is shown, in this case an embodiment in which the side stays 76, 77 made of steel wire are replaced by supports 89 stiffened against buckling. Although these will in many cases be expensive because of the special form, they have the advantage that the bowsprit 60 and the forestay 75 can be dispensed with. In order to give the supports 89 an a large as possible buckling stiffness with as low a weight as possible, they are shown barrel-shaped in Fig. 3.
Fig. 4 is a schematic diagram of the attachment of the front float to the starboard and port frame beams 51 and 52 near the point at which they join at the bow of the vessel. As mentioned before, the tubular stub 44 is anchored in the float. In the case of the front float, which for steering is pivotable around a vertical centre line with respect to the frame 5, there is no rear tubular stub 25 in the front float 4 such as is used in the rear floats 2 and 3. Because the front float 4 is connected to the vessel only by the tubular stub 44, this tubular stub should be sufficiently robust. Its position with respect to the length of the float is determined such that while sailing no great torque will be required to pivot the float for the purpose of steering. This applies for a fully lowered centreboard 46 as well as for the centreboard being in other positions. The position of the tubular stub 44 is therfore determined by the steering characteristics of the front float 4. It will be clear that the position determined thus can also be applied without difficulty to both the rear floats 2 and 3 in the form of the tubular stubs 24 and 34. As shown in Fig. 4, the tubular stub 44 extends upwards for some distance and is surrounded by a plastic bearing liner 64, made for example from nylon. The tubular stub 44 is closed off at its top end with a robust plate 65 in which a bolt can be screwed which is rotatably placed in a cap 66 that closes off the bearing bush 67 on the upper side, which bearing bush surrounds the bearing liner. The bearing bush 67 is welded to a top plate 68 and a bottom plate 69 which extend sideways and can be fixed with schematically shown bolts to the starboard and port side beams 51 and 52. In order to prevent shifting schematically shown retaining pins can be pushed through the clamping positions on the side beams 51 and 52. The axial locking is achieved with a nylon disc 64a, which is retained with a little play between the end of the tubular stub 44 and the bearing liner 64 on the one side and the cap 66. There is also a nylon disc between the head of the bolt and the top hand of the cap 66. It will be clear to a person skilled in the art, however, that the pivotable means of attachment shown in Fig. 4 can be replaced by many other embodiments.
A steering structure 9 is shown schematically in Fig. 5. In the figure the frame 5 is shown schematically in thin lines and the front float 4. The tiller 91 is shown pivotable around a vertical axis 92 and is drawn with a deflection to the left, which for the usual ships means that the vessel is making a turn to starboard. This means that the front float 4 must change the course to starboard. The pivoting axis 92 of the tiller 91 is pivotably attached in an unspecified manner in the middle of the stern beam 53. In a manner comparable to a normal rudder arm 93 extends backwards to which a starboard steel cable 94 and a port steel cable 95 are connected. These run over schematically shown guide rollers 96 at the corners 54 of the frame in order to run forwards along or possibly through the side beams 51 and 52 and approximately at the points 57 and 58 to run round guide rollers 96 again and then to be connected to the rear of the front float 4. The starboard steering cable 94 is, according to Fig. 5, connected to the port end of the float 4 at location 97 while the port steering cable 95 is attached to the starboard rear end 98 of the float 4. This overlapping means of attachment for both the steering cables 94 and95 has the advantage that the steering movement of the front float can be much greater than would be the case if the crossed means of attachment were not be used. It will be clear that many other means of transferring the steering command from the tiller 91 to the front float 4 are possible. In this respect it may be mentioned that, in contrast to normal vessels, where the rudder is placed at the rear and consequently the stern is pushed sideways during manoevres, the vessel according to the invention is steered at the front and consequently sails a course which is comparable to that of a car on land. Nevertheless it seems to be worthwhile to use the means of transferring the steering command outlined in Fig. 5 because this resembles that with which the average yachtsman is familiar.
Fig. 5 shows a plan view of a vessel according to the invention with rear steering by means of the two pivotable rear floats 2 and 2. They are pivotably attached to the frame at the locations 24 and 34 with a structure which is in principle similar to that according to Fig. 4. longer and slimmer floats are used. With the aid of a steel cable 94, 95, run over pulleys 96 attached to the rear of the floats, and attached to the stern beam 53 at the locations 97, 98 respectively, the floats are steered essentially parallel to each other by the tiller 91, 93. In order that the steel cables 94, 95 remain tensioned, the floats are connected to each other at their fronts with a steel cable 99.
In order to prevent the tendency of the front float 4 to dip too far into the water when the vessel lists strongly, the front float can similarly pivot around a vertical axis 44 and is connected via springs 100 from its rear with the starboard beam 51 and the port beam 52 respectively at the locations 102. The springs are attached to the float at the locations 101. The springs try to bring back or keep the float at the centre position with respect to frame. Automatic course correction is achieved with said construction. An additional advantage is that all the floats are thus completely identical.

Claims

1. Sailing vessel with three hull-shaped floats, of which at least two are adjacent and positioned at a distance from and essentially parallel to each other, and comprising in addition a rigid connecting structure between the floats, steering gear connected to a tiller at the stern, a mast with stays, a sail with an adjustable clew connection in the rear underside region to a fixed part of the connecting structure, and a taut net stretched between the connecting structure in the stern area and serving as a working surface for the yachtsmen, characterized in that the third float (4) is positioned as a front float at a fair distance in front of the two adjacent rear floats (2, 3) and on the longitudinal centre line, and in that the plan view of the connecting structure (5) takes the form of an isosceles triangle or isosceles trapezium of which the base forms the stern beam (53) and the equal sides the starboard (51) and the port (52) beams, and the apex or short parallel side forms the junction at the bow (59), and there being, in the region of the corner joint (54) between the starboard beam (51) and the stern beam (53), means of attachment (24, 25, 57) to the rear starboard float (2) and similarly on the port side (3; 34, 35, 57), and in the region of the bow junction for attachment (44; 64-69) to the front float (4), and the frame (5) being - when the vessel is ready for sailing - essentially horizontal.

2. Sailing vessel according to Claim 1, characterized in that the attachment means of the front float (4) to the frame in the region of the junction at the bow is constructed pivotably about an axis (44) which is vertical with respect to the frame and is connected by connecting means such as steel wires (94, 95) and guide rollers to the tiller (91, 92, 93) at the stern for the purpose of steering the vessel.

3. Vessel according to Claim 2, characterized in that the floats are constructed as a completely closed ship's hull having a length between about 1/3 to 1/4 of the length of the connecting frame (5).

4. Vessel according to Claim 1, characterized in that the two rear floats (2; 3) are attached to the frame so that they can pivot around a vertical axis through the attachment point (24; 34) and are connected by linking means, such as steel wires and guide rollers, to the tiller (91, 92, 93) such that they remain essentially parallel to each other at all positions of the rudder.

5. Vessel according to Claim 4, characterized in that the front float (4) is similarly attached to the frame so that it can pivot around a vertical axis through the attachment point (44) and in that, for automatic course compensation when the vessel is heeled over to a great extent, a prestressed elastic component (100), such as a spring, is positioned between the rear of the front float and both the starboard beam (51) and the port beam (52), which components always attempt to keep the front float (4) in a central position with respect to the vessel, all this such that the front float can make an angle of up to about±10° with respect to the centre line of the frame.

6. Vessel according to Claim 4 or 5, characterized in that each float (2, 3, 4) has a length equal to about 0.5 times the length of the frame (5).

7. Vessel according to one or more of the preceding Claims, characterized in that each float (2, 3, 4) is provided with a cutwater (23, 33, 43) or keel beam which extends essentially over the whole underwater length of the float.

8. Vessel according to one or more of the preceding Claims, characterized in that all three floats (2, 3, 4) are essentially identical to each other.

9. Vessel according to one or more of the preceding Claims, characterized in that the foot of the mast (7) is placed in the frame (5) in the region of the bow junction (59), and in that the mast leans back at an angle of between about 25° and 35° from the vertical, preferably at an angle of about 30°.

10. Sailing vessel according to Claim 9, characterized in that a rigid bowsprit-shaped extension (60) is attached to the frame (5) for attaching the fore stay (75) of the mast (7) thereto and in that the side stays (76, 77) rise upwards towards the stern from the port (52) and starboard beams (51) of the frame (5) at a slight angle of about 5° to 10° with respect to a vertical to the frame (5) seen in side view of the vessel.

11. Sailing vessel according to Claim 9 characterized in that the staying of the mast (7) consists exclusively of a side staying formed by a buckle stiffened shores (89) at starboard and one at port which is respectively strutted on the starboard or port beam respectively at a slight angle of about 5° to 10° directed upwards towards the stern, seen in a side view of the vessel.

12. Sailing vessel according to one or more of the preceding claims characterized in that the rigged sail (8) has a free (loose) underside (81) and in that the clew (83) grips the rear bottom corner (82) of the sail, which point is near a vertical plain through the stern beam (53) of the frame when the sail is spanned amidships.

13. Sailing vessel according to one or more of the preceding claims, characterized in that a guide eye or guide block (85) of the clew (83) is displaceable along a guide rail or run-over (62) which extends over the whole length (width) of the stern beam (53) of the frame.

14. Sailing vessel according to one or more of the preceding Claims, characterized in that all the attachment devices between the frame (5) and the floats (2, 3, 4) are easily detachable and in that the frame is constructed of essentially straight beams (51, 52, 53, 55) and small corner connectors (54) with the aid of similarly easily detachable attachment devices such as mortise and tenon constructions and clamping brackets.