The subject invention concerns a sailing boat which is not limited to any particular class and which may be used as a leisure craft as well as a race boat.

Conventional sailing boats operate on the principle that the effects of the wind acting on the sails of the boat are balanced by the force and the moment which are generated by the keel of the boat when the keel cuts down into the water. The resistance of the water and the weight of the keel are used to generate said force and said moment. The speed of conventional sailing boats is determined by several different factors. The most important one is the area of the sails and the configuration of the keel and of the hull. To enable the use of large sail areas the prior-art technique proposes various keel shapes to generate a force and a moment to balance the load of the wind on the sails. One example of a sailing boat designed on this principle is the successful Australia II, winner of America ^' s Cup. However, large keels suffer from the drawback that they have a drag effect on the boat, slowing it down and thus to some extent counteracting the gains of speed obtained by the increase of the sail area.

The purpose of the subject invention is to suggest a sailing boat which is designed for sailing using large sail areas without it being necessary to design the boat with a conventional type of large keel. Further advantages in the sailing boat in accordance with the invention will become apparent from the following description. The purpose of the invention is achieved therein that the sailing boat is provided with at least one pivotally mounted mast, that it is

equipped with a regulating system which is arranged to maintain the mast in a vertical neutral position while subjecting it to a predeter¬ mined biasing force, that the regulating system is arranged to gene¬ rate a balancing moment about the centre of movement of the boat for the purpose of counteracting the moment generated by the load of the wind on the sails and that this balancing moment is generated by displacement of one or several balancing members arranged for movement.

Further characteristics of the invention will become apparent from the dependent claims.

The invention will be described in closer detail in the fol¬ lowing with reference to the accompanying drawings, wherein

Figs. 1 and 2 are skeleton views of the sail ng boat showing it in different operational positions in accordance with the inven- tion,

Figs. 3 - 6 are skeleton views showing the principles of the invention for the purpose of illustrating and comparing the sailing characteristics of a conventional sailing boat and those of the sail¬ ing boat in accordance with the invention, Figs. 7 and 8 show the principles of an alternative embodiment of the sail ng boat in accordance with the invention.

Figs. 1 and 2 show schematically the manner of operation of the sailing boat 10 in accordance with the invention. The boat com¬ prises a mast 12 which is pivotally mounted on a shaft 14 so as to be able to tilt in the transverse direction across the sailing boat 10. In the initial or neutral position shown in Fig. 1 the mast is main¬ tained in the vertical position by means of two or several guy wires or cables 16 which are secured to the piston rods 20 of hydraulically operated piston-and-cylinder units 18, one on either side of the boat. The piston-and-cylinder units 18 preferably are single-acting and arranged to exert a predetermined biasing force on the wires 16.

The piston-and-cylinder units 18 are part of a hydraulic sys¬ tem which also includes a double-acting hydraulically operated p ston- -and-cyl nder unit 22 which communicates with the piston-and-cylinder units 18 through lines 24 and two expansion tanks 26.

A set of weights 30 are arranged so as to be shiftable in the transverse direction across the hull 28 of the sailing boat 10. The weights 30 are arranged in any practically suitable manner, for in¬ stance so as to be displaceable inside a channel provided in the hull

5 of the boat. The weights 30 serve as balancing members and stabilize the sailing boat 10.

The sailing boat in accordance with the invention functions in the following manner. When the wind acts on the sail the mast 12 tilts in the manner illustrated in Fig. 2. One of the wires 16 (the left one

1.0 in accordance with Fig. 2) is paid out and hydraulic fluid then flows from the associated hydraulic p ston-and-cylinder unit 18 to the double-acting hydraulic piston-and-cylinder unit 22, the piston rod 32 of which is displaced from its central position or position of equilibrium with a force which corresponds to the load of the wind on

15 the sails. Hydraulic fluid flows into the opposite piston-and-cylinder unit 18 and the wire 16 on this side is paid in, with the result that the wire 16 is at all times kept in a taught condition. The amount of paying-in of one wire slightly exceeds the amount of paying-out of the other wire.

20 The movement of the piston rod 32 is util zed to displace the weights 30 to a position in which the weights will generate a moment about the centre of movement of the boat sufficient to balance the load of the wind on the sails and to keep the hull 28 of the sailing boat 10 horizontal. The load is transferred from the piston rod 32 to

25 the weights by means of a mechanical and/or hydraulic system (not shown in the drawings). For instance, the system may be designed in such a manner that the piston rod 32 is in the form a gear rack with which engages a cog wheel. The cog wheel is connected to a second cog wheel or several gears or the like to drive an endless chain which is

30 connected to the train of weights 30. The power transmission between the cog wheel and the gears could be mechanical or hydraulic and the gear ratio should be suitably dimensioned. When hydraulic power trans¬ mission is used between the cog wheel and the gear the designer has a comparatively large freedom of choice as regards the positions of the

35 hydraulic piston-and-cylinder unit 22 and the expansion tank 26 in the hull 28. It may be advantageous to position these items "out of the way", for instance in the aft part of the boat 10.

A couple of springs 34 are provided in order to dampen un desirable and sudden movements of the weights 30. The springs 34 are hooked onto the weights 30 in the position of equilibrium of the latter and are designed to extend when the weights 30 move. The expan- sion tanks 26 dampen sudden movements in the hydraulic system, which movements may arise as a result of e.g. sudden wind shifts or gusts of wind and absorb slackness, if any, in the wires.

Owing to the movements of the weights 30 transversely across the hull 28 the hydraulic system of the sailing boat 10 generates a moment which balances the moment which is generated by the wind acting on the sails of the boat 10. The hull 28 will be horizontally posi¬ tioned in the water, irrespective of the magnitude of the wind-force load on the sails. The configuration of the hull 28 without a large keel of the conventional type results in a sailing boat 10 which is less deep-drawing than are conventional sailing boats and as a result thereof it is also faster. Its navigability is increased which lessens the risk of grounding during disembark ent alongside jetties and the like.

The sailing boat 10 in accordance with the invention is more stable than conventional sail ng boats since the hull is at all times maintained in a horizontal position in the water and the force of the wind is balanced by the displacement of the weights 30. By choosing the mass of the weights in relation to the weight of the boat it be¬ comes possible to increase the area of the sails considerably compared with conventional sailing boats. With a weight of the elements 30 equalling that of a corresponding keel and with equal displacement, tests have shown that it is possible to increase the sail area by 35% or more. This possibility, too, attributes to the increased speed of the sailing boat 10 in accordance with the invention compared with that of conventional sailing boats.

The hull 28 tends at all times to assume a horizontal position in the water, which facilitates all movements and displacements on¬ board. The sailing boat 10 increases the safety of the crew, since the hull 28 has no tendency to keel over. Consequently, the onboard com- fort is increased.

The rudder of the ship (not shown) always assumes a vertical position and thus its function is always optimum. Rudders on

conventional sailing boats assume angular position during sailing with resulting impairment of their steering function.

It is possible to arrange for some of the items of the sailing boat, such as fuel tanks, engine, water tanks etcetera, to be dis- placeable together with the weights. If this is the case the mass of the weights 30 may be reduced and therefore the displacement of the boat 10 may be decreased or the area of the sails be increased.

The hull 28 may be designed with the primary view to further the speed of the boat, as the latter will not lean over during sail- ing. The comparatively flat hull and the consequential small deep- -drawing also facil tate propulsion of the boat by motor. The plane hull of the boat contributes to making it more suitable for high speeds than conventional sailing boats which have a comparatively large keel. The hull 28 will not either have any tendencies of cutting down into the water.

Some quantities, such as the mass of the weight 30, the bias¬ ing force on the guy wires 16, are chosen in consideration of the qualities that are desired in the boat. The stiffness of the mast 12, for instance, may be chosen for adapation to the winds and drift conditions. A spr ng 38 may be provided to act on the piston-and-

-cylinder unit 22 to control the operation of the hydraulic system and the system inertia.

Fig. 3 shows the differences in behaviour between a con¬ ventional sailing boat 40 and the sailing boat in accordance with the invention when exposed to the effects from comparatively hard winds. The mast 12 of the boat 10 in accordance with the invention assumes the same angle as does the mast 42 of the sailing boat 40. The sailing boat 10 has a sail area which by 35% exceeds that of an otherwise comparable, conventional sailing boat 40. Thehull of the sailing boat 40 heels over heavily whereas the hull 28 of the sailing boat 10 is horizontal .

Fig. 4 shows a sailing boat 40 that has capsized. The mast 42 of the boat 40 is in a horizontal position and its keel 44 has emerged above the waterlevel. Fig. 5 illustrates the sailing boat 10 in accordance with the invention with its mast 12 in a horizontal posi¬ tion. The boat 10 is not overturned and the weights 30 are in a posi¬ tion in which they tend to turn the hull 28 of the boat 10 back to

the horizontal position. The sail ng boat 10 in accordance with the invention thus is capsize-proof. The moment exerted by the weights 30 will turn the hull of the boat 10 to the horizontal position illu¬ strated in Fig. 6. Contrary to what is the case in conventional sailing boats it is not necessary to reef the sails first.

Figs. 7 and 8 illustrate the principles on which another poss¬ ible embodiment of the sailing boat in accordance with the invention is constructed. The sailing boat is provided with an external, movable keel which serves as a balancing means corresponding to the weights 30. The keel is movable in a watertight channel 39 and its position is controlled by the same hydraulic system as that controlling the weights 30. The hydraulic system is connected with the means regulat¬ ing the position of the keel 36 by means of a shaft 40 which passes through a watertight mounting in the hull. The embodiments of the invention described in the aforegoing are to be regarded as examples only and as mentioned in the descrip¬ tion several other embodiments are possible within the scope of the invention as the latter is defined in the appended claims. A smaller keel or a centreboard may be provided, if desired. The centreboard may be adjustable vertically for optimum adaptation to the existing conditions.