GB2299798A - A device for controlling the lateral movement of the boom of a sailing boat. - Google Patents

Abstract

The boom 2 of a sailing boat is fitted with a clamping device 6 through which is passed a rope 7 fixed at both ends. When the rope 7 is clamped by the clamping device 6 the boom 2 is prevented from swinging laterally. The clamping force is increased by passing rope 7 a number of times round a non-rotating drum 19 forming part of the device. The clamping force is generated by passing rope 7 through a clamping element 20 external to drum 19 which can be drawn towards the axis of drum 19 by a mechanism which includes a toggle linkage which reaches top dead centre in the clamping position. The linkage can be operated by a remote control element 9 in such a way that pulling the remote control element causes boom 2 to be locked and releasing it allows the boom to swing freely. The device can be attached to a track formed in the underside of boom 2 by a split mounting 15 which can be inserted anywhere along the length of the track without disturbing other fittings.

Description

A DEVICE FOR CONTROLLING THE LATERAL MOVEMENT OF THE BOOU OF A SAILING BOAT This invention relates to a device for controlling'the lateral movement of the boom of a sailing boat.

The lateral position of the boom of a sailing boat is normally controlled only by a rope purchase known as the main sheet one end of which is attached to a point on the boom and the other end to a point near the longitudinal centreline of the boat. It is possible for a boat to be sailed in such a way that the the wind acts on the opposite side of the sail to that which normally drives the boat forward with the result that the sail causes the boom to swing violently over to the other side of the boat at a speed which cannot be controlled by the main sheet. This can happen unexpectedly and cause injury to the crew of the boat or damage to the rigging.

The purpose of the invention which was described in my patent application to be published as Go2283470 was to enable the helmsman or a crew member to lock the boom in any selected position by remote control from the cockpit so that it was prevented from swinging as described above. A further purpose was to allow the boom to swing over slowly under the same remote control.

Although a device as described in that application served the first purpose, it has been found that when an attempt is made to use it for the second purpose, the change between static and moving friction between the transverse rope and the device is too sudden for human reaction times to control and also that under heavy braking loads the friction is sufficient to melt the surface fibres of a transverse rope made of the usual polyester.

A further drawback to a device as then described is that it can only be used on boats up to a certain size, because the greater the tension in the transverse rope the greater has to be the pull on the remote control element to release the lock. Since this pull is limited to what a human can exert, the device can only be used to control mainsails up to a certain area.

One purpose of the present invention is to overcome both these drawbacks so that the device can be used as a brake without overheating the transverse rope and also that it can be used on larger sizes of sailing boat.

The boom of a sailing yacht is usually made from an aluminium extrusion which incorporates a track along its underside into which can be fitted load-bearing slides to one of which is attached a fastening for the main sheet and to another of which is attached a fastening for a rope purchase or rigid strut known as the boom vang. One or both ends of this track are closed off by end cap castings.

Another purpose of the present invention is to enable the mounting for the boom movement controlling device to be fitted into the boom track anywhere along its length without the need to disturb other fittings or remove end caps.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows in perspective a sailing boat with the clamping device mounted on the boom and the associated rope and remote control element; Figure 2 shows the side elevation of the clamping device in the free position; Figure 3 shows the side elevation of the clamping device internal mechanism in the locked position; Figure 4 shows the side elevation of the clamping device internal mechanism in the free position; Figure 5 shows the end elevation of the clamping device and mounting slide; Figure 6 shows the side elevation of an alternative clamping device in the free position using an additional rope turn; Figure 7 shows the side elevation of an alternative clamping device with the clamping element reversed and in the locked position;; Figure 8 shows the plan view and side elevation of an over-centre lever which can be used to operate the remote control; Referring to the drawings Fig 1 shows a boat with mast 1, boom 2, sail 3, main sheet 4 and boom vang 5. The boom movement control device 6 is mounted on the underside of boom 2 and a rope 7 runs between fixed points 8 on either side of the boat through the movement control device 6. A remote control extended element 9 runs from device 6 through a pulley block 10 located in substantially vertical alignment with boom pivot 11 and then back to a cleat 12 within reach of cockpit 13.

Fig 2 shows the device in the free position. The body 14 is pivotally connected by pivot pin 17 to a boom track mounting consisting of two half slides 15 made from aluminium extrusions or other material which can be inserted separately anywhere in the track and then slid and bolted together with bolts and nuts 16, so forming a trunnion through which is passed pivot pin 17. A variety of slides 15 can be machined from one basic extrusion in order to accomodate a range of different boom track shapes and sizes.

The transverse rope 7 passes through guide ring 18 and round drum 19 which is non-rotationally connected to body 14 and through clamping element 20 and on round drum 19 to exit through guide ring 21 on the opposite side.

The internal clamping mechanism 22 is fastened to body 14 by fixings 23 and when remote control element 9 is pulled, clamping element 20 is drawn towards the axis of drum 19 and compresses rope 7 against drum 19 in order to prevent relative movement between rope 7 and drum 19 and in this way locks boom 2 against lateral movement.

Nounting slides 15 are prevented from movement along the track in boom 2 by a stop plate 24 attached to boom 2 by screw or screws 25.

Fig 3 shows the internal mechanism in the clamped position with body 14 shown in chain dot. Clamping element 20 is pivotally connected to clamp bar 26 by pivot 27 and can move up and down between a pair of longitudinal bars 28 forming a slot in drum 19. This slot can be recessed below the outside surface of drum 19 to improve the clamping characteristics.

Clamp bar 26 is pivoted about pivot 29 and its offset from the pivot is variable by means of screw 30 and nuts 31 so that the degree of clamping can be adjusted.

The position of clamp bar 26 is controlled by means of a toggle linkage consisting of lever 32 and link 33 extending between pivot 34 on body 35 and pivot 36 at the end of clamping bar 26. A pair of tension springs 37 are connected between pin 38 on lever 32 and pin 39 on clamp bar 26. These tend to bring the linkage to the position shown in Fig 4.

Remote control element 9 is connected to the end of lever 32 by link 40 and when pulled brings the toggle linkage close to the top dead centre position.

This final position is controlled by means of stop block 41 striking the end of adjuster screw 42. In this position rope 7 is compressed against drum 19 and this locks boom 2 in position so that it can not swing.

Fig 4 shows the clamping device when remote control element 9 has been released. When clamping element 20 is in this position rope 7 is free to move around drum 19 and this allows boom 2 to swing freely from side to side.

Fig 5 shows the end elevation of the clamping device and in particular how slides 15 are bolted together by bolts 16 and fit into the track on the underside of boom 2. It also shows how mechanism 22 is inserted into body 14 through slot 43 formed in one end of body 14. It also shows how the pair of longitudinal bars 28 form a slot in drum 19 through which clamping element 20 can project. These bars may be recessed below the outer surface of drum 19 in order to improve clamping efficiency.

Fig 6 shows the side elevation of an alternative construction in which rope 7 is given an extra turn around drum 19 in order to increase the frictional resistance to relative movement between rope 7 and drum 19 when remote control element 9 is pulled which has the effect of pulling clamping element 20 towards the axis of drum 19. In this construction the internal mechanism is similar to that shown in Fig 4, but with lever 32 replaced by lever 44. The mechanism is also inverted. Because of this, remote control element 9 is passed through a pulley block 45 swingably attached underneath boom 2.

Fig 7 shows the side elevation of a further alternative construction in which clamping element 20 is inverted from the position shown in Figs 3 and 4. This has the effect of reversing the action of the remote control element 9 so that pulling it releases the clamp and releasing it allows springs 37 to draw clamping element 20 towards the axis of drum 19 and so clamp rope 7 against drum 19 to lock boom 2 against swinging. The mechanism is shown in the clamped position.

Fig 8 shows the side elevation and plan view of an over-centre lever which can be used at the cockpit end of remote control element 9. Lever 46 rotates about pivot 47 in mounting bracket 48 and carries pivotally a block 49 which includes a hole through which passes a tube 50 screued externally. The remote control element 9 passes through tube 50 and is restrained from being pulled through the tube by means such as a stop knot 51. Two knurled nuts 52 provide an adjustment which can be used to ensure that the internal mechanism 22 reaches the correct position when clamped.

Any of the clamping devices described could be attached rigidly to boom 2 instead of pivotally.

Claims (16)

1. A device for controlling the movement of the boom of the mainsail of a sailing boat which is attached to the boom and in which a rope fixed at both ends passes round a non-rotating drum forming part of the the device and in which the degree of friction between the drum and the rope is regulated by controlling from a remote point a clamping element which compresses a part of the rope against the drum and in which the remote control element increases the compression force when pulled.

2. A device as claimed in claim 1 in which a spring or springs release the compression force when the remote control element is released.

3. A device as claimed in claims 1 and 2 in which the action is reversed so that pulling the remote control element releases the compression force and in which releasing the remote control element allows springs to increase the compression force.

4. A device as claimed in any preceding claim in which the rope passes through guide rings on both sides of the drum.

5. A device as claimed in any preceding claim in which the part of the rope compressed by the clamping element is substantially midway along the rope between the initial points of contact between the rope and drum on either side of the drum.

6. A device as claimed in any preceding claim in which the clamping element passes through the drum and exerts a clamping force on the rope which acts substantially towards the axis of the drum.

7. A device as claimed in claim 5 in which the surface of the drum is recessed where the clamping element passes through it.

8. A device as claimed in any preceding claim in which the clamping element is forced to compress the rope by means of a toggle linkage which reaches or nearly reaches top dead centre at the instant of maximum compression.

9. A device as claimed in any preceding claim in which one part of the toggle linkage is extended to form a lever to the outer end of which is attached a remote control element.

10. A device as claimed in any preceding claim in which a remote control extended flexible element is passed through a pulley block attached to a fixed point on the boat or the mast substantially in vertical alignment with the boom pivot and then back to a jamming or cam cleat near the cockpit of the boat.

11. A device as claimed in claim 10 in which the jamming or cam cleat is replaced by a toggle lever to which the remote control element is attached in such a way that the attachment point passes top dead centre when the remote control element is fully extended.

12. A device as claimed in Claim 11 in which the remote control element is attached to the toggle lever in such a way that the length of the element can be adjusted by a screw adjustment.

13. A device as claimed in any preceding claim in which the device is pivotally connected to the boom by means of a pivot whose axis is substantially in lateral alignment with the axis of the boom.

14. A device as claimed in claims 1 - 12 in which the device is attached to the boom in a way which substantially prevents relative movement between them.

15. A device as claimed in any preceding claim in which the mounting parts to attach the device to the boom consist of two parts which can be inserted separately at any point in the boom track and then slid and bolted together to form a mounting to support the device.

16. A device for controlling the movement of the boom of a sailing boat substantially as described herein with reference to Figures 1 - 8 of the accompanying drawings.