SAIL APPARATUS AND EXTENDIBLE MEMBER SUITABLE FOR USE IN THE SAIL APPARATUS
There is discussed a sail apparatus having a sail with one or more battens. A furling system varies the area of deployed sail between a furled state and an unfurled state by rotating the sail about the leading edge. At least one batten comprises a single extendible sheet member operable to switch between a rigid three-dimensional longitudinal state and a coiled planar state, such that a deployed portion of said at least one batten is in said rigid, three-dimensional longitudinal state and a furled portion of said at least one batten is in a coiled planar state. The batten is resiliently baised towards the leading edge of the sail, while allowing movement of the batten towards the trailing edge of the sail during furling.
This application claims priority from UK patent application no. 1119750.6 filed on 15 Nov. 2011 and from UK patent application no. 1200248.1 filed on 6 Jan. 2012, which are both incorporated herein in their entirety by reference.
BACKGROUND OF THE INVENTIONb 1. Field of Invention
In one aspect, this invention relates to a sail apparatus, and in particular to a sail apparatus in which a sail is furled and unfurled about its leading edge. In another aspect, this invention relates to an extendible member which may be used as a batten in the sail apparatus, and a method of manufacture therefor.
2. Description of Related technology
It is well known that battens can increase the area of a sail beyond the area which is directly supported by the tension within the sail. The additional area, sometimes referred to as the roach of the sail, is supported by the rigidity of the battens to maintain the desired aerodynamic profile. Battens are typically located toward the trailing edge of the sail and their main axis intersects the leading edge, sometimes referred to as the luff edge, of the sail.
A problem occurs when it is desired to use battens in combination with a sail rig in which the sail is furled/unfurled by winding/unwinding the sail around an axis which runs along the leading edge of the sail. Such a ‘roller-furling’ sail rig allows the area of deployed sail to be easily and quickly varied. However, the rigidity of conventional battens is incompatible with winding the sail about the leading edge.
At least two different techniques have been used to address this problem. U.S. Pat. No. 4,633,798 discusses using battens formed by a thin, resilient material having a curved, stable state but being deformable into a planar state for furling. In practical implementations, it has been typically necessary to employ two such battens facing each other, but even with two battens the stiffness is not particularly high. In addition, the stresses applied to the battens in the curled state as a result of the resilience of the battens tends to weaken the battens. Further, the battens may damage the sail material.
WO 94/14648 discusses an alternative technique utilising inflatable battens. The need for inflation/deflation equipment makes this technique expensive, and also prone to mechanical failure. Further, the time taken to inflate and deflate the battens make them unsuitable for competitive sailing, and in certain circumstances could be a safety concern.
SUMMARY OF THE INVENTIONAn object of the present invention is to provide an alternative solution to the problem of using battens with a ‘roller-furling’ sail rig. Aspects of the invention are set out in the accompanying claims.
An embodiment of the invention comprises using sail battens formed by a single extendible sheet member which has two stable states: a rigid three-dimensional longitudinal state in which the cross-section of the sheet member generally forms an arc; and a coiled planar state in which the cross-section of the sheet member is generally linear. In use, the extendible sheet member switches between the rigid three-dimensional longitudinal state and the coiled planar state at a position which varies in response to winding/unwinding the sail about its leading edge. In the rigid, three-dimensional longitudinal state, the extendible sheet member stiffens the sail to provide an effective roach area. The coiled planar state allows the sail to be furled/unfurled using a ‘roller-furling’ sail rig.
WO 97/35706, the whole contents of which are hereby incorporated by reference, discusses an extendible sheet member which can be adapted for use in the present invention. The extendible sheet member of WO 97/35706 has two stable states, a tubular extended state and a planar coiled state. Transition from the tubular extended state to the planar coiled state is effected by manually manipulating one end of the sheet member to have a planar cross-section. For the purposes of the present invention, such direct manual manipulation is not feasible. Accordingly, in a preferred embodiment, the extendible sheet member of WO 97/35706 is modified by chamfering one end when in the tubular state. In this way, the act of winding/unwinding the sail about the leading edge causes the transition point between the tubular extended state and the coiled planar to move along the length of the extendible sheet member so as to remain adjacent to the leading edge as the sail is furled/unfurled without the need for any direct manual manipulation of the extendible sheet member. If the cross-section of the sheet member in the tubular state extends more than 180°, then the chamfered end may be splayed to ensure that at a transition point between the rigid tubular extended state and the coiled planar state, the cross-section of the sheet member forms an arc having an extent of not more than 180°.
The modifications made to the extendible sheet member of WO 97/35706 are considered to be inventive independent of the sailing application, and would be advantageous in other applications where direct manual manipulation of the extendible sheet member is either unfeasible or undesirable.
In another embodiment, there is provided a sail having a roller-furling rig, with sail battens mounted to the sail. The sail battens are mounted to allow the battens to move aft as the sail furls. Preferably, this is achieved using a resilient mounting.
By way of example, various embodiments of the invention will now be described with reference to the accompanying figures, in which:
A first embodiment of the invention will now be described with reference to
The furling system of this embodiment is provided with actuators (not shown) which apply a force to the trailing edge 11 of the sail 1 in a direction along the boom 5 away from the mast 3 to unfurl the sail 1 and which apply a rotational force to the foil 15 to furl the sail 1. These actuators may either be motorised, pneumatic or manually driven using, for example, a winch.
In this embodiment, the battens are made using the extendible sheet members discussed in WO 97/35706. Such extendible sheet members are available from Rolatube Technology, 130 Wellworthy Road, Ampress Park, Lymington, 5041 8JY, UK. In this embodiment, various modifications are made to the extendible sheet member of WO 97/35706 to make the extendible sheet member more suitable for use as a sail batten.
In order to facilitate furling of the sail 1, in this embodiment the end 27 of the batten 7 which, in use, is proximate to the leading edge 9 of the sail 1 is modified to facilitate initiation of the transition from the three-dimensional longitudinal state to the planar coiled state. In particular, as shown in
In this embodiment, the end 27 of the batten 7 proximate the leading edge 9 of the sail 1 is splayed by a thermoforming process in which the end is heated, shaped using a mould and then allowed to cool into the new shape.
For illustrative purposes,
In this embodiment, the pocket 21 is formed of an elastic material. In this way, the pocket 21 contracts against the sail 1 during furling, allowing the furled sail to be more compact. However, using an elastic material for the pocket 21 is not essential.
A second embodiment will now be described in which the trailing end of the batten 7 is modified to facilitate passage through a narrow slot in a mast during an unfurling operation. As shown in
As shown in
In the first and second embodiments, in the three-dimensional rigid state the cross-section of the batten over the central portion of its length is almost circular. A third embodiment will now be described with reference to
As shown in
When mounted to a sail, the rounded end 105 forms the trailing end of the batten 101. As shown in
As shown in
As shown more clearly in
As shown in
Although the extendible sheet members used to form the battens of the first to third embodiments have sufficient stiffness to support the roach area of the sail in most applications, in some applications it may be desirable to further stiffen the battens. To address this, a fourth embodiment will now be described with reference to
As shown in
In this embodiment, the reinforcing member is formed by a plastic member formed into a two-dimensional arc across its major length. . Other materials may, however, be used, but it is crucial that they are manufactured from a material that has mechanical properties that allow it to be rolled with the batten, many times without degradation.
Modifications and Further EmbodimentsIn the first embodiment, the sail 1 is a mainsail whose leading edge 9 is attached to a foil 15 within a mast 3. The invention is applicable to other sail apparatus in which a sail is wound and unwound about its leading edge. For example, as shown in
The first embodiment discusses one way in which the end of a batten proximate the leading edge of the sail can be structured to facilitate the transition of the batten between the three-dimensional longitudinal state and the coiled planar state by a rolling operation without any direct manual access to the batten. Alternative arrangements are possible. For example, the end of the batten proximate the leading edge of the sail could be permanently maintained in the coiled planar state by keeping a portion of the sail permanently wound about its leading edge.
The modifications to the extendible sheet member of WO 97/35706 made in the first embodiment may have application outside of a sail apparatus to facilitate transition of the extendible sheet member from the three-dimensional longitudinal state to the planar coiled state without direct manual manipulation. For example, such a mechanism could be used to deploy and retract an arm member in an unmanned deep sea vessel, or to retract a probe arm in a hazardous area.
While it is preferred that the chamfered end of the batten be splayed, this is not essential.
While the extendible sheet member of WO 97/35706 is convenient for implementation of the present invention, alternative extendible sheet members which transition between two stable states, one in which the sheet member is in a three-dimensional longitudinal state and the other in which the sheet member is in a planar coiled state, could be used.
In the second and third embodiments, a resilient member provides a bias force to urge the battens towards the leading edge of the sail when unfurled, while allowing the battens to move towards the trailing edge of the sail during furling. Such a resiliently-biased arrangement may be used with other types of battens, not just those employing bistable extendible sheet members as exemplified in the disclosure of WO 97/35706.
In the third embodiment, a button member 119 is utilised but the button member 119 is not necessary and may be omitted.
Claims
1. Sail apparatus comprising:
- a sail having a leading edge and one or more battens; and
- a furling system operable to vary the area of deployed sail between a furled state and an unfurled state by rotating the sail about the leading edge,
- wherein at least one batten comprises an extendible sheet member operable to switch between a rigid three-dimensional longitudinal stable state and a coiled planar stable state, such that when deployed said at least one batten is in said rigid, three-dimensional longitudinal stable state and when furled said at least one batten is in said coiled planar stable state.
2. Sail apparatus according to claim 1, wherein said rigid three-dimensional longitudinal state has a cross-sectional profile in the shape of an arc.
3. Sail apparatus according to claim 2, wherein said rigid three-dimensional longitudinal state has a generally tubular profile.
4. Sail apparatus according to claim 2, wherein said rigid three-dimensional longitudinal state has a profile in the form of an arc having a central angle of 180° or less.
5. Sail apparatus according to claim 2, wherein the extendible sheet member has an outer end toward the trailing edge of the sail and an inner end toward the leading edge of the sail, wherein said inner end is chamfered to facilitate initiation of the transition from the rigid three-dimensional longitudinal state to the coiled planar state upon rotation of the sail about the leading edge.
6. Sail apparatus according to claim 5, wherein said inner end is splayed such that a cross section through the cross-section of the extendible sheet member at a transition point between the rigid, three-dimensional longitudinal state and the coiled planar state forms an arc having a central angle of 180° or less.
7. Sail apparatus according to claim 5, wherein the outer end of the extendible sheet member has a rounded profile in a plane normal to the surface of the sail and along the main axis of the batten.
8. Sail apparatus according to claim 5, wherein the outer end of the extendible sheet member is chamfered.
9. Sail apparatus according to claim 1, further comprising a resilient biasing arrangement to urge the batten toward the leading edge of the sail.
10. Sail apparatus according to claim 9, wherein the resilient biasing arrangement comprises an elastic cord.
11. Sail apparatus according to claim 10, wherein the elastic cord is threaded through the sail and the corresponding batten.
12. Sail apparatus according to claim 1, wherein said at least one batten further comprises a reinforcing member.
13. An extendible sheet member operable to switch between a rigid three-dimensional longitudinal stable state and a coiled planar stable state in which the extendible sheet member is coiled about a coil axis, the extendible sheet member having an end which is chamfered to facilitate initiation of a transition from said rigid three-dimensional longitudinal stable state to said coiled planar stable state in response to rotation of the extendible sheet member about the coil axis from said chamfered end.
14. An extendible sheet member according to claim 13, wherein said chamfered end is splayed such that a cross section through the cross-section of the extendible sheet member at a transition point between the rigid, three-dimensional longitudinal state and the coiled planar state forms an arc having an extent of not more than 180°.
15. An extendible member according to claim 13, wherein the other end of the extendible sheet member has a rounded edge.
16. Sail apparatus comprising:
- a sail having a leading edge;
- a furling system operable to vary the area of deployed sail between a furled state and an unfurled state by rotating the sail about the leading edge;
- one or more battens; and
- for each of the one or more battens, a resilient biasing arrangement providing a biasing force in the direction of the leading edge of the sail and allowing movement away from the leading edge of the sail as the batten rotates around the leading edge of the sail when transiting from the furled state to the unfurled state.
17. Sail apparatus according to claim 16, wherein the resilient biasing arrangement comprises an elastic cord.
18. Sail apparatus according to claim 17, wherein the elastic cord is threaded through the sail and the corresponding batten.
19. Sail apparatus according to claim 16, wherein at least one batten comprises an extendible sheet member operable to switch between a rigid three-dimensional longitudinal stable state and a coiled planar stable state.
20. Sail apparatus according to claim 19, wherein the extendible sheet member has an outer end toward the trailing edge of the sail and an inner end toward the leading edge of the sail, wherein said inner end is chamfered to facilitate initiation of the transition from the rigid three-dimensional longitudinal state to the coiled planar state upon rotation of the sail about the leading edge.
Type: Application
Filed: Nov 14, 2012
Publication Date: Jul 25, 2013
Applicant: Primrose Fry Technologies Limited (Alton)
Inventor: Primrose Fry Technologies Limited (Alton)
Application Number: 13/676,347
International Classification: B63H 9/06 (20060101);