GB2187152A

GB2187152A - A stabilising device for sailing boats

Info

Publication number: GB2187152A
Application number: GB08604302A
Authority: GB
Inventors: Robert Colin Harvey Webb
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-02-21
Filing date: 1986-02-21
Publication date: 1987-09-03
Also published as: GB8604302D0

Abstract

A stabilising device for sailing boats allows a mast and integrally linked keel 5 to tilt laterally under wind pressure on the sails without the boat tilting as well; thus allowing the use of a narrow streamlined hull. The weighted keel 5 and the mast are pivotted so that the keel is angled from the fore-and-aft line 2 of the boat in direct proportion to the degree of tilt and in such a manner that water pressure on the side of the keel serves to reduce that tilt. The associated rigging device incorporates a 'through' jib 13 and mainsail boom 18 which revolves around the mast. This boom has 'travellers' 17 attached so that both jib and mainsail can be set or can set themselves to prescribed positions for optimum air flow. The rigging can therefore be controlled from the confined position associated with the narrow hull. <IMAGE>

Description

SPECIFICATION Stabilising device and associated rigging device for sailing boats This invention relates to a stabilising device and associated rigging device for sailing boats.

Most sailing boats rely, fortheir lateral stability against wind pressure on the sails, on the beam-width of the boat, the weight of any keel and the ability of the crew to move to the windward side to act as a counterbalance.

There are a number of disadvantages with these factors and they are most relevant if the boat is not planing orcannot plane. Theyare: 1. Although greater beam-width means greater stability it also means increased water resistance to forward movement and less speed if not planing.

2. Hull design is made more difficult because it has to give the optimum results atvarying degrees of lateral tilt to the water: if the hull when sailing could remain mai nly verticai when thought of in cross-section, design would be easier and give better results.

3. To allowforthe helmsman or crew to move around the boat- for counterbalancing ortending to the rigging - a considerable percentage of the volume of the hull has to be above the waterline. This increases weight, water displacement and drag.

4. Toprevent'running under'thevolumeofthe hull above the waterline is generally greater at the bow and this means considerable resistance to waves and wind especially when sailing into the wind.

It is therefore felt desirable to provide means whereby: 1. Lateral stability against wind pressure on the sails is principally achieved by different factors, thus enabling the design of sailing boats with narrow hulls and less drag 2. The volume, area and weight ofthe above-water parts of the boat are reduced so that there is less wave and wind resistance and so that thesmallervolumeofunderwaterhull requiredto produce buoyancy reduces drag 3. The helmsman or crew, within the reduced space ofthe narrowed hull and smaller superstructure as indicated in 1 and 2 above, can operate controls and rigging from a confined position.

According to the present invention there is provided a stabilising device and associated rigging device for sailing boats wherein there is a mast which can pivot on a fore-and-aft axis of the boat and which is integrally linked with a weighted keel which also pivots on such an axis, a meansforanglingthe keel in a deviation from the fore-and-aft line ofthe boat in direct proportion to the degree of mast and keel tilt in order to allow the water pressure on the side of the keel to reduce this ti It, optional and controllable lateral fins atthe bow or stern to control the passage of the bow through the water and an integrally linked 'through'jib and mainsail boom which can revolve around the mast and which can be controlled from a confined position in the boat and yet atthe same time allow a sail rig that can optimise wind forces over a variety of points of sailing.

Specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings on sheets 1/5 to 5/5 and in Figures 1 to 10inwhich:- Sheet 1/5 Figure 1 shows, in perspective (and for clarity abstracted from a boat), the mast/keel stabilising device and also the associated rigging device Sheet 2/5 Figure 2 shows, in a side view, the stabilising device and rigging device applied to a known kayakform of narrow-hulled boat Figure 3 indicates schematically, in a section A- A from Figure 2, the mast/keel tilt principle Sheet 3/5 Figure 4 shows the pivoting mechanism in sideview Figure5showsthe pivoting mechanism in plan view with the hinged keel clamp open ready to receive the keel Figure 6shows the pivoting mechanism in plan view with the hinged keel clamp closed (keel itself not shown) Figure 7shows a downward looking perspective view ofthe pivoting mechanism which indicates how the keel is angled when pivoted Sheet 4/5 Figure 8 and Figure 9 are comparative illustrations showing the principles associated with the rigging device Sheet 5/5 Figure 10 shows a method of linking the pivoting of the mast to that of the keel when they are on similar but separated and parallel axes.

Referring to Sheet 1/5 Figure 1 the pivoting mechanism 1 is situated on a fore-and-aft line 2 of a boat (not shown); the forward pivot 3 is on this line.

The aft pivot 4 is set eccentrically higherthan pivot 3 so that as the mast and keel tilt under lateral wind pressure the aft end of the keel is laterally transposed and the keel angled to the fore-and-aft line of travel of the boat in such a way that the water pressure on the side of this angled keel tends to revert it and the mast to a neutral position: (also illustrated in Sheet 3/5 Figure 7). The greaterthe degree oftilt ofthe mast/keel the greater the angling of the keel and the greater its neutralising effectwhen the boat is moving.

5 is the keel which in this example is shown as having three parts (for greater portability) linked together when clamped into the pivot mechanism. 6 shows the keel parts lifting hooks which could also be handles. 7 shows flanges at the top of the keel parts enabling them to be rested on the pivot mechanism priortothe hinged clamping bar8 (see also Sheet 3/5 Figures 5 and 6) being closed. The clamping bar locates and confines the keel but allows movementbackwardstospace9and/or vertically upwards to the extent of the narrow part of the keel 10 both of which movement-allowances being safety devices to prevent damage to mast or hull in the event of the keel meeting an underwater obstruction.

11 is the mast socket which in this example is integrally partofthe pivot mechanism. 12 isthe rigging device which in this example comprises twin 'through' jib-to-mainsail booms 13 fixed to a bearing plate 1 4which in turn is fixed to a sleeve 1 5which slots overthe mast. The bearing piate 14 also has fixed to it a jib traveller 16 and the aft ends ofthetwin 'through' booms have a mainsail traveller 17 fixed to them. 18 is a subsidiary mainsail boom integrally linked to the twin 'through' jib-to-mainsail booms by thetraveller 17.

The jib and mainsail travellers 16 and 17 automatically allowthe sailsto set themselves under wind pressure to a prescribed position to obtain optimum wind flow over them (further described when referring to the illustrations on Sheet 4/5).

19 is an optional control sparwhich can be used instead of a sheet from the end of the subsidiary boom 18. The whole of the rigging device with its attached sails can be revolved around the mast so thatthe correct entry of the wind onto both thejib andthe mainsail can be achieved (furtherdescribed when referring to the illustrations on Sheet 4/5).

20 is a mast clamp which prevents the boom sleeve 15 rising under tension from the sails to the mast head.

On Sheet 2/5 Figure 2 illustrates an example ofthe invention applied to a known type of kayakwherein the kayak is converted from a two-seater version for use by paddling to a single-seater sailing boat. This is achieved by mounting the invention in the forward cockpit. Control by the helmsman from the confined position of the aft cockpit is maintained in this example by a conventional sheet attached to the end ofthesubsidiaryboom 18.

There is an angle between the horizontal and the fore-and-aft line ofthe 'through' booms wherein the forward end of the jib at 21 is lowerthanthe aft end of the subsidiary mainsail boom at 22. This is so that when the masttilts and the rigging device rotated for the correct angle of wind entry onto the sails the 'through' boom can be horizontal or nearly so for average sailing conditions (see also Figure 3). The exact angle would be determined at a development stage.

Water entry through the bottom of the hull where the keel and pivoting mechanism operate is contained in a conventional centreboardfashion which is elaborated to allowforthe lateral travel of the mast and mast socket. A suitably modified canoe-type spray deck prevents entry of water the main hull from thetop.These points are not illustrated.

In an alternative application of the invention a solid hull can be used. Such a hull could be similarto a displacement surfboard and in such an application the necessity of excluding entry of water to the hull would not arise.

On Sheet 215 Figure 3 schematically illustrates, in an elaborated cross section A- Afrom Figure 2, the pivoting principle. For simplicity the angling ofthe keel from the fore-and-aft line is notshown.

On Sheet 4/5 the principle of the rigging device and the reasons for its association to the stabilising device are shown in two Figures8and9. Italso shows its use in optimising wind forces. Figure 8 shows a known type of ordinary sail boat and Figure 9 an example ofthe invention, both Figures in simplified diagram form. With the stabilising device it is desirable to reduce if possible the stabilising effect required by the weight of keel and the means shown in the invention for keel angling. In comparing the two figures it will be seen that the weight disposition of the rigging is more evenly balanced in Figure 9 and not all on one side ofthe boat. Similarly both the downward and forward part of the wind forces acting on the sails is more evenly balanced from one side of the boat to the other.

The concept of the stabilising device and its relationship to narrow hulls with less structure above the waterline requires a control of the rigging from a more confined space than a conventional sailboat. In the example ofthe invention diagramatically illustrated in Figure 9the desired angle of entry ofthe wind on the sails can be achieved from one position by allowing the whole 'through' boom to rotate to that required position.

This effectively sets the luff of both jib and mainsail correctly. By having travellers for both the jib and mainsail fixed to the 'through' boom (shown on Sheet 1/5 Figure 1 but not on Sheet 4/5 Figure Sfor sake of clarity) the amount that both sails can be let out is pre-determined so that the optimum 'slot effect' of the wind passing from the windward side of the jib to the leeward of the mainsail is achieved and can be maintained over a wide variety of points of sailing. In Figure 8for instance the conventional form of boat has largely lost the effectiveness of the 'slot' because thesails have had to be let out so far; in Figure 9 howeverthe 'slot' is still effective.

On Sheet 5/5 Figure 10 shows, in a hull cross section at mast point, a method of linking the mast and keel if the pivoting of the mast is removed from the same axis as the pivoting ofthe keel. For instance it can be desirable that the mast is pivoted at deck level rather than at the level ofthe keel pivot. In this illustration the mast extension 23 below the pivot point 24 has a slot 25 at its end in which bears a spigot 26 attached to a chain 27 which can run freely buttightly around gear wheels 28. The tilting ofthe mast imparts a motion to the chain via the above connections which in turn imparts a similartilt to the keel 29 via the keel extension arm 30, the slot 31 and the duplicate chain spigot 32. The mast extension arm and the keel extension arm are at opposite sides of the gearwheel/chain mechanism.

An alternative version would have two gearwheels only and both versions can be equipped with chain guides two prevent the chain sagging.

Claims

1. A stabilising device and associated rigging device for sailing boats wherein there is a mast which can pivot on a fore-and-aft axis of the boat and which is integrally linked with a weighted keel which also pivots on such an axis, a means for angling the keel in a deviation from the fore-and-aft line of the boat in direct proportion to the degree of mast and keel tilt in order to allow the water pressure on the side of the keel to reduce this tilt, optional and controllable lateral fins at the bow or stern to control the passage of the bow through the water and an integrally linked 'through'jib and mainsail boom which can revolve around the mast and which can be controlled from a confined position in the boat and yetatthe same time allow a sail rig that can optimise wind forces over a variety of points of sailing.

2. A stabilising device and associated rigging device for sailing boats wherein there is a mast which can pivot on a fore-and-aft axis of the boat and which is integrally linked with a weighted keel which also pivots on such an axis and a means for angling the keel in a deviation from the fore-and-aft line of the boat in direct proportion to the degree of mast and keel tilt in order to allowthe water pressure on the side of the keel to reduce this tilt.

3. A stabilising device and associated rigging device as claimed in Claims 1 and/or 2 wherein the angling of the keel is achieved through the aft pivot point being higher, in relation to the main fore-and-aft line of the boat, than the forward pivot point, orviceversa.

4. A stabilising device and associated rigging device as claimed in Claims 1 and/or 2 wherein the angling of the keel is achieved by gearing.

5. Astabilising device and associated rigging device as claimed in Claims 1 and/or 2 wherein the angling of the keel is achieved by rods or levers.

6. A stabilising device and associated rigging device as claimed in Claim 1 and/or2whereinthe angling ofthe keel is achieved by any combination of the means claimed in Claims 3, 4and 5.

7. A stabilising device and associated rigging device as claimed in Claims 1 and/or 2, and 3wherein the mast which is integrally linked with theweighted keel, pivots on the deviatedfore-and-aft line of the keel pivot.

8. Astabilising device and associated rigging device as claimed in Claims 1 and/or 2, orany preceding claims wherein the mast pivot is separate from the keel pivot and is linked to it by mechanical means.

9. An associated rigging device as claimed in Claim 1 wherein the integrally linked 'through'jib and mainsail boom is angled sothattheforward end is lowerthan the aft end.

10. An associated rigging device as claimed in Claim 1 wherein the integrally linked 'through'jib and mainsail boom is staggered so thattheforward end is lowerthan the aft end.

11. An associated rigging device as claimed in Claims 1,9 and 10 wherein 'travellers' are fixed to the 'through' jib and mainsail boom allowing the jib and mainsail to be set orto set themselves automatically to prescribed positionsto allow optimum airflow over the sails.

12. An associated rigging device as claimed in Claims 1 and 11 wherein the 'travellers' are adjustable.