WO1989009159A1 - Sailing yacht - Google Patents

Abstract

A sailing yacht (10) is disclosed having a pair of independently pivotable wings (30) and (32) each extending laterally from the yacht's keel (16). The pivot axis (34) around which each wing may pivot is disposed at a point along the length of the wing intermediate the leading edge (36) and trailing edge (38) of the wing.

Description

SAILING YACHT

This invention relates to boats and, in particular, to a boat keel which is particularly suitable for sailing yachts.

It is known that a yacht sails at its fastest when the hull is effectively upright in water but, where the wind is abeam of a yacht, there is an inherent turning moment that causes the yacht to heel.

This heeling has normally been minimised by providing a relatively heavy keel to lower the centre of gravity of the yacht as much as possible and thereby provide a turning moment which opposes that caused by the wind striking the sails.

It has been proposed, for instance in Australian Patent Application No. 85668/82, to provide wings fixedly disposed and extending laterally from the keel of a yacht. Such arrangements have found some favour in yacht racing where the wings are said to generate lift and side force when the yacht heels.

It has also been proposed in Australian Patent Application No. 52624/86 to dispose pivotable aerofoils on a yacht keel to gain lift or manoeuvrability from the hydrodynamic effect of the aerofoil shape. The aerofoils disclosed in this document are pivoted adjacent their leading edge and accordingly when pivoted up or down produce undesirable drag as they effectively act in a similar fashion to brake flaps mounted on aircraft wings.

It is an object of the present invention to provide an improved yacht having a winged keel.

According to the present invention there is provided a sailing yacht comprising a hull, from which in use a sail-bearing mast projects upwardly, and a keel assembly depending from the hull, the keel assembly comprising a substantially planar keel and a wing projecting from each side of the keel adjacent a bottom portion thereof, each wing being independently pivotable relative to the keel about an axis which extends laterally of the plane of the keel and which is remote from both a leading edge and a trailing edge of the wing. It is preferred that the movement of each wing can be achieved from a position in the yacht readily accessible to an operator, and the linkage to appropriate control means may be by, for example, cable, chain, gears, levers, hydraulic circuitry, pneumatic circuitry and/or electro-mechanical circuitry.

The keel of the yacht may be essentially conventional and be of any suitable substantially planar shape which will usually extend downwardly from the centre line of the yacht. The wings may extend outwardly from the keel either normally to the plane of the keel or inclined to the plane. Preferably, each wing is mounted for rotation about an axis which lies in the plane of the wing.

The wings are each preferably substantially planar and arranged so that in a neutral position they extend horizontally. Conveniently, each wing tapers or otherwise leads into the leading edge. The wings may have a substantially aerofoil cross-section or, for example, a cross-section which tapers from the pivot axis to both the leading edge and the trailing edge, preferably with the upper and lower contours being a mirror image of each other. Thus each wing may have a flattened or elongate kite shaped quadrilateral or rhomboid cross-section.

A major feature of the present invention is providing the pivot axis for each wing at a position remote from the leading and trailing edges of the wing so as to provide improved control of the balance of the yacht. A wing pivoted adjacent its leading edge will not function satisfactorily, particularly due to the difficulty in adjusting its inclination. Advantageously, each wing is pivoted approximately centrally of its length or most preferably somewhat forwardly of the central axis to lessen the force required to return the wing to the neutral position. In the case of a substantially aerofoil section, the pivot axis may be, for example, approximately one-third of the length of the wing back from the leading edge, but other shapes may advantageously have the pivot axis only slightly forwardly of the central axis of the wing, for example about 10 cms forwardly of the central axis of a 3 m long wing. Preferably the leading edge of each wing, when in a leading edge down attitude, does not extend below the keel so that the water flow over the wing does not affect water flow on the other side of the keel. Advantageously the leading and trailing edges of each wing do not extend beyond the fore and aft edge respectively, of that portion of the keel at which they are adjacent.

The yacht of the present invention is such that the angle of attack of each wing relative to a horizontal plane can be varied and thus reactive forces relative to the hull can also be varied. Because there will be substantial forces when the wings are at a positive or negative angle of attack to the direction of movement of the yacht, it may be desirable to provide trim tabs on these, which trim tabs act as a servo-mechanism to facilitate the wing being maintained at its required angle.

In operation, when the yacht has what is effectively a tail wind, that is when it would generally be substantially upright in the water, both wings may be disposed in a neutral substantially horizontal position so that drag is minimised. However, if it is required to alter the overall trim of the yacht, the wings could both be given the same angle of attack to either provide a slight upward force, which would cause the yacht to have a slight nose up orientation or a slight downward force, which would cause the yacht to have a slight downward orientation. Advantageously, both wings are moved under these conditions into a position in which their leading edges are raised so as to create lift at the bow which may result in reduced water resistance and produce a planing effect. When the wind strikes the yacht from abeam so the yacht tends to heel, the wings may be adjusted so that the wing on the lee side adopts a leading edge raised attitude so as to attempt to lift the yacht. The weather side wing may be maintained in the neutral position or adjusted so that it adopts a leading edge lowered attitude which tends to lower that side of the yacht. There is thus a turning force upon the keel to move the yacht towards a more upright position.

Depending upon the strength of the wind, and its angle of attack, so the degree of movement of the wings can be varied to provide an optimum situation for the orientation of the yacht. In these applications it would be possible to interlock the wings so that the degree of inclination upwardly in one wing would be directly reflected in the degree of inclination downwardly of the other wing. In other conditions, such as where the sea is also having an effect on the yacht, as well as the wind, it may be desirable that the degree of inclination of one wing be different from the degree of inclination of the other wing so that there is a differential in effect from each side which would enable the best sailing condition to be achieved. Because of the various possibilities of adjustment, it may be possible to use the wings to produce a downward drag, where necessary, and to reduce the mass of the keel or other ballast accordingly. It may also be possible for the yacht to carry an increased sail area.

Various embodiments of a sailing yacht in accordance with the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1 is a side elevation of a first embodiment of the yacht; Figure 2 is a front view of the yacht of

Figure 1;

Figure 3 is a view similar to Figure 2 but showing a second embodiment of the yacht;

Figure 4 is an enlarged side view of the wings of the second embodiment of the yacht, with the keel removed for clarity;

Figure 5 is a plan view of the wings of Figure 4 ;

Figure 6 is a view similar to Figure 2 but of a third embodiment of the yacht with the hull omitted and only part of the keel shown;

Figure 7 is a view similar to Figure 4 but showing the wings of the third embodiment.

Figure 8 is a schematic perspective view of a fourth embodiment of the yacht having a pair of levers operable to displace respective wings which are similar in shape to those of the second embodiment;

Figure 9 is a side sectional view through the keel of a fifth embodiment showing an hydraulic piston operating a lever to displace a wing;

Figure 10 is a schematic perspective view of a sixth embodiment having chain driven gears operable to displace respective wings and wherein the yacht has been omitted for clarity; and

Figure 11 is a side view of a seventh embodiment in which a wing is displaceable by an hydraulic piston within the keel operating on a trailing end portion of the wing. The yacht 10 shown in Figures 1 and 2 comprises a hull 12 and a keel assembly 14 including a fin-like keel 16 which depends from the bottom of the hull 12 along the centre line of the yacht and approximately centrally of the hull 12 in the fore and aft direction. The cross-section of the keel 16 is clear from Figure 2 and it will be understood that the keel is substantially planar with its principal plane shown at 18. In use, a mast (not shown) would extend upwardly from the deck 20 of the hull to support one or more sails. The bow of the hull is shown at 22 while the stern 24 includes a stern fin 26 which may incorporate a rudder. Alternatively, the rudder may be incorporated as part of the keel assembly 14.

Adjacent the bottom portion 28 of the keel 16, two wings 30 and 32 are supported on respective sides of the keel for independent pivotal rotation relative to the keel. The pivot axis 34 of the wings 30 and 32 extends in a normal direction to the principal plane 18 of the keel and in the plane of the substantially planar wings. In fact, the upper and lower surfaces of the wings 30 and 32 are each in the shape of an aerofoil so have a somewhat bulbous leading edge 36 and a finely tapered trailing edge 38. The pivot axis 34 of each of the wings 30 and 32 extends transversely of the wing at between one third and one half of the length of the wing from the leading edge 36. The off-setting of the pivot axis 34 from the leading edge 36 has been found to provide major advantages in the efficiency of the wings 30 and 32 and of their displacement. The wings are independently pivotable to raise and lower the leading edge 36 from a neutral position in which the wings preferably extend horizontally so as to minimise drag through the water in this position. The maximum angle of upward or downward pivotal movement from the neutral position is about 20°. Figures 1 and 2 show the leading edge 36 of the starboard wing 30 lowered and the leading edge 36 of the port wing 32 raised relative to the neutral position.

The means for pivotally adjusting each wing 30 and 32 is shown schematically in Figure 1 in the form of a chain 40 which extends around a sprocket (not shown) associated with the respective wing and a crank handle 42 for shifting the associated chain 40 and rotating the respective sprocket and wing. This mechanism is described in greater detail in relation to the embodiment of figure 10. Clearly other control means may be proposed and the chains 40 or other linkages conveniently pass through a corresponding passage in the keel 16 to engage the respective axle on the pivot axis 34 in a manner which seals the outside water from the passage. For the sake of convenience, the terms "raised wing" and "lowered wing" will be used to define, respectively, the situation where the leading edge 36 of the wing is raised and where the leading edge 36 of the wing is lowered. Figure 2 illustrates the forces involved when the starboard wing 30 is lowered and the port wing 32 is raised. The port wing creates a lifting force while the starboard wing creates a downwards force thereby creating an anti-clockwise moment N (when viewed from the bow 22) about the axis 44 of the yacht. Such an arrangement of the wings 30 and 32 would be used to right the yacht 10 when the wind is blowing into the sails from the starboard beam 46 which tends to cause the yacht to heel to port. In some conditions, it may not be necessary to move the windward wing (in the example described above, the starboard wing 30) out of the neutral position but the optimum settings may be investigated by experimentation.

Figure 3 illustrates a second embodiment 50 of a yacht in accordance with the present invention in which the only difference of any substance over the yacht 10 lies in the wings 52 and 54 which are supported for independent rotation relative to the keel on the axle 34. Accordingly, only the wings 52 and 54 will be described in detail and they are shown in enlarged manner in Figures 4 and 5. In Figures 3 and 4, the starboard wing 52 is shown in the lowered position, that is with the leading edge 56 lowered and the trailing edge 58 raised, while the port wing 54 is shown in the neutral position. The wings 52 and 54 are oblong in plan view and taper in profile from a relatively thick central portion 60 which receives the axle 34 to the relatively narrow leading and trailing edges 56 and 58. Thus, the profile of the wings 52 and 54 is substantially of a flattened diamond shape or elongate kite shaped guadrilateral with the upper leading face 62 being substantially parallel to the lower trailing face 64. Likewise, the lower leading face 66 of each of the wings extends substantially parallel to the upper trailing face 68, the terms leading and trailing implying fore and aft, respectively, of the axle 34. In the embodiment shown, the parallelism is not absolute since the axle 34 is offset forwardly to a small degree from the transverse centre line of each of the wings. The ratio of length between the axle and the leading edge 56 and the trailing edge 58, respectively, is 1.8:2.

The sleeving of the axle 34 is shown schematically in Figure 5 at 70. Referring now to Figures 6 and 7, the keel

16 of a yacht 80 is shown in which the primary difference over the yacht 50 is the shape of the wings 82 and 84. The yacht 80 is shown with the starboard wing 82 in the neutral position and with the port wing 84 in the raised position, that is with the leading edge 86 raised and the trailing edge 88 lowered.

The wings 82 and 84 are similarly mounted for independent rotation on the axle 34 and have a similar shape except that they are of constant thickness so that the upper and lower faces 90 and 92 respectively are parallel except at the leading edge portion 94 where they taper equally to the central leading edge 86. Figure 8 illustrates a simple mechanism to independently displace each wing. The wings may be of any suitable shape but are shown as of similar shape to the wings 52 and 54 in Figures 3 to 5. In figure 8 the yacht 90 has wings 92 and 94 mounted on respective sides of lower portion of a keel 96 depending therefrom. Each wing 92,94 is pivoted on a respective axle (not shown) extending into the keel 96. Lower end portions 97,99 of two levers 98,100 are non-rotatably attached to the axles, by such means as cooperating splines, so that displacement of the levers 98,100 causes the wings to be rotated on the axles. In figure 8 the port wing 92 is shown in a leading edge raised attitude, having been displaced by the lever 100, and the starboard wing is shown displaced by the lever 98 into a leading edge lowered attitude. The wings may each be approximately the same length as the beam of the yacht.

The upper end portions 101,103 of the levers 98,100 may engage respective arrays of notches provided in a gate 102 set into the deck of the yacht to resist displacement of the lever after the desired inclination of the wings has been set. The levers are preferably biased into the respective array of notches for example by suitable springing or by their inherent resilience. In figure 9 a cross-section of the starboard side of a keel 112 of a further embodiment of a yacht 110 in accordance with the invention is depicted. This embodiment employs a conventional hydraulic cylinder 114 to operate a lever 116 which is non-rotatably attached by splines to a pivot axle 118 supporting a wing 119 which is shown as of similar shape to the wings 52 and 54 in Figures 3 to 5. The hydraulic cylinder 114 and lever 116 are mounted within a cavity 120 in the keel. The hydraulic lines 122,124 powering the hydraulic cylinder are connected through a suitable valve mounted on the deck of the yacht to a conventional hydraulic pump (not shown). The valve on the deck allows the crew to control the hydraulic cylinder and thus the angle of the wing. A similar arrangement of hydraulic cylinder and lever mounted within a cavity in the port side of the keel powers the port wing.

Figure 10 shows a still further arrangement to allow independent displacement of the wings.

Only the features of the drive mechanism 130 of the embodiment have been shown with the yacht keel and hull omitted for clarity. Each wing 132,134 is mounted on a respective half shaft 136,138 which extends within the keel (not shown) normal to its plane. Each half shaft 136,138 has a respective sprocket 140,142 non-rotatably mounted thereon. Each sprocket 140,142 is driven by a respective chain 144,146 and hand cranked gear box 148,150. The gear boxes 148,150 are mounted on the deck of the yacht to enable the crew to displace the wings by manually cranking the gear box. Alternatively the gear boxes may be driven by respective electric or hydraulic motors.

A still further arrangement for displacing a wing is depicted in Figure 11 which is a side view of a keel 160. A starboard wing 162 is shown in the leading edge raised attitude. The wing 162 is pivoted on an axle 164 extending transversely from the keel 160. At an inboard edge of the trailing end portion 166 of the wing, adjacent the surface of the keel 160, a finger 168 extends from the wing into a vertical slot 170 disposed in the keel. Within the slot 170 the finger 168 engages the remote end portion 172 of the piston 174 of an hydraulic cylinder 176 mounted within the keel 160. Extension and retraction of the piston 174 in turn rotates the wing 162 around the axle 164. A similar arrangement is provided within the port side of the keel to displace a port wing.

In an alternative embodiment the hydraulic cylinder may act on the leading end 162 of the wing. It can be seen in this embodiment that the leading and trailing edge of the wing do not extend beyond the fore or aft edge respectively of the keel nor below its deepest edge so as to prevent interference of the water flow around one wing by the water flow over the opposite wing.

Although not clearly shown in the drawings,

5 it is preferred that the axially inner edge of the wings follows as closely as possible the adjacent contour of the keel while still permitting the wings to be displaced upwardly and downwardly.

It will be appreciated by those skilled in the lOart that the described embodiments may be modified or improved in various ways while retaining the essence of the invention, and all such modifications an dimprovements should be considered as within the scope of the patent application. In particular, the independent displacement

15of the two wings may be performed in any number of ways and the invention should not be considered as limited to any one approach.

Claims

1. A sailing yacht comprising a hull, from which in use a sail-bearing mast projects upwardly, and a keel assembly depending from the hull, the keel assembly comprising a substantially planar keel and a wing projecting from each side of the keel adjacent a bottom portion thereof, each wing being independently pivotable relative to the keel about an axis which extends laterally of the plane of the keel and which is remote from both a leading edge and a trailing edge of the wing.

2. A sailing yacht according to claim 1 wherein the upper and/or lower surface of each wing is of aerofoil section.

3. A sailing yacht according to claim 1 wherein each wing is of elongate kite shaped or rhomboid quadrilateral section and wherein the pivot axis is disposed in the plane defined between the upper and lower vertices of the quadrilateral section.

4. A sailing yacht according to claim 1 wherein the pivot axis of each wing is forward of the centre of the length of the wing.

5. A sailing yacht according to claim 1 wherein each wing is pivotable by means of a respective hydraulic piston and cylinder assembly engaging the trailing or leading portion of the wing.

6. A sailing yacht according to claim 1 wherein each wing is pivotable by a respective rotation means acting within the keel upon a shaft defining the pivot axis of the wing.

7. A sailing vessel according to claim 6 wherein each rotation means comprises a lever non-rotatably attached to the shaft.

8. A sailing yacht according to claim 7 wherein the lever is actuated by a hydraulic piston and cylinder assembly.

9. A sailing yacht according to claim 6 wherein each rotation means comprises a chain or gear driven sprocket on the shaft.

10. A sailing yacht according to claim 1 wherein the axially inner edge of each wing substantially follows the adjacent contour of the keel.