EP1446524A1

EP1446524A1 - A method of manufacturing an elongate structural member

Info

Publication number: EP1446524A1
Application number: EP02801408A
Authority: EP
Inventors: John David Boyce
Original assignee: Boyce Spars Holdings Ltd
Current assignee: Boyce Spars Holdings Ltd
Priority date: 2001-10-15
Filing date: 2002-10-15
Publication date: 2004-08-18
Also published as: GB2380984A; GB2380984B; GB0124736D0; WO2003033814A1

Abstract

A method of manufacturing an elongate structural member in which a tow of composite prepreg (70) is wound around two spaced apart mandrels (50, 60). The wound tow (70) is then heated to cure resin in the prepreg. The elongate structural member produced by this method has two integral through holes formed by the mandrels (50, 60). A tie of composite material having two spaced apart through holes and comprised of filaments set in resin is also disclosed.

Description

A METHOD OF MANUFACTURING AN ELONGATE STRUCTURAL

MEMBER

The present invention relates to a method of manufacturing an elongate structural member, to an elongate structural member, to a tie and to a component of standing rigging. The elongate structural member and tie may be used as a structural members for resisting forces in applications such as the standing rigging of boats, civil engineering, and other applications. The tie is designed to resist tensile forces. Figure 1 of the accompanying drawings illustrates schematically the standing rigging of a sailing boat. Standing rigging is a term used to describe all of the rigging of a boat used in the support of the mast 12. The standing rigging comprises vertical sections 16 which extend from the region of the deck of the boat to the top of the mast 12 and are held away from the mast by spreaders 14. Diagonal sections 18 of rigging extend between the outer most ends of the spreaders 14 and the mast 12. The vertical and diagonal sections support and control the bend of the mast.

Both the vertical 16 and diagonal 18 portions of the standing rigging are in tension. Conventionally 1 x 19 stainless steel wire rope with turned over eyelets and compression joints has been used for the vertical 16 and diagonal 18 components. On some large yachts stainless steel rope rigging has been replaced by polished steel rods with swaged ends with through holes drilled through them which form convenient attachment portions. A problem with both of these systems is of weight. The weight of the mast and rigging is one of the forces which has to be counter balanced by the keel 20 attached to the bottom of the hull. This balances the boat by counteracting the turning moment produced on the hull by the mast and rigging. On large yachts the depth of the keel and its weight must be large because of the large weight and therefore large turning moment of the mast 12 and associated standing rigging. Thus, there has been a concerted effort to reduce the weight of standing rigging. To this end some of the diagonal components 18 have been made of kevlar (TM) rope. The problem with kevlar (TM) rope rigging is one of creep: although each individual strand of kevlar (TM) has a high Young's modulus and tensile strength, the rope tends to creep when initially loaded. According to the present mvention there is provided a method of manufacturing a composite elongate structural member with two through-holes, said method comprising the steps of: providing two spaced apart mandrels; winding at least one tow of composite prepreg around the outer sides of both of said two spaced apart mandrels together, such that at least part of said tow extends between said two mandrels; and heating said wound tow between and around said mandrels to cure resin in said composite prepreg, thereby to solidify said tow as said composite elongate structural member with said through-holes being integrally formed by said mandrels. In this way a composite elongate structural member is produced in which the through holes, which may be used as attachment portions, are an integral part of the member. The filaments of the tows are orientated for maximum tensile strength of the elongate structural member in a direction substantially between the through holes. The wrapping of the filaments around the through holes ensures continuity of strength around those through holes such that there is little, if any, compromise in strength in those areas.

Preferably, during said step of heating, said mandrels are positioned one above another, such that said part of said tow extending between said two mandrels is substantially vertically orientated. It has been found that elongate structural members prepared by the method of the present invention which are cured in a horizontal position in an oven can suffer from reduced strength near the attachment portion. It is thought that this is the result of the slight arcuate shape that the wound tow assumes under the influence of gravity between the two mandrels. When the resultant elongate structural member is put in tension, this arcuate shape results in a component of the force in the elongate structural member not being applied in a direction directly between the through holes and can thus result in early failure. If the elongate structural members are positioned in an oven vertically such that the tows between the mandrels are substantially vertically orientated, the effect on the shape of the elongate structural member due to gravity, can be minimised. This results in a stronger member.

A simple way of achieving vertical orientation of the tow between the two mandrels is by suspending the wound tow from the top mandrel of the two spaced apart mandrels. A further way of improving the method is by providing the oven in which the step of heating occurs, as an elongate oven in the vertical direction. In this case, a fan may be needed in the oven effective to circulate air in the oven. If this fan is not provided it is possible that the temperature at the top of the oven is too high and the temperature at the bottom of the oven is too low.

Alternative ways exist for ensuring that the elongate structural members are cured straight. In one alternative, the members are positioned with mandrels one above the other (optionally with tension) and, instead of being cured in an oven, an electrical current is passed through the member to heat it and thereby to cure the resin. This alternative has the advantage of not requiring a vertical oven. It can even be carried out horizontally with the element supported so that it cures flat.

Another alternative is to cure the member by pulling it through a heated die. The prepreg enters the die uncured and exits in a cured state. Thus, even for very long members, there can be no sagging of the prepreg during curing because the prepreg cures in the die short lengths at a time. This method has the advantage of taking up little space and having no limit as to the size of member producible and there is no need to have axially wound filaments to hold the longitudinally wound filaments together. In a preferred embodiment, the member is pulled vertically through the die.

Preferably at least some of the filaments of the tow extend between and around the mandrels a plurality of times. This continuity results in good tensile strength of the elongate structural member because the resin of the composite does not need to take very much strain during tensioning of the elongate structural member.

In a preferred embodiment of the method, after the step of winding and before the step of heating there is provided a further step of gathering together the parts of the windings extending between the mandrels by winding the tow around and axially along the parts between said mandrels. Doing this keeps all parts of the tow together during the heating step.

Advantageously the mandrels are metal rings and during the step of winding the tows are wound around the outer side of said rings. These rings can be retained as integral parts of the elongate structural member and provide convenient attachment portions for the elongate structural member. Even more advantageously the metal ring can have an inner concave bearing surface against which a convex bearing surface of an outer member abuts, such that the inner members are rotatable within the rings. This further simplifies tensioning of the elongate structural member in use and, when fatigue of the elongate structural member is a problem, can result in reduced fatiguing loads of the elongate structural member because the elongate structural member can move relative to the structure to which the elongate structural member is attached. Other forms of connector may be provided in the through-holes in the composite. They may either be inserted after winding (or curing), or be incorporated integrally by being used as mandrels for the winding process. For example, the connector may be a sold rod.

Sometimes an elongate structural member with increased resistance to abrasion is required. In this case, the method may further comprise a step of covering the composite elongate structural member by covering a with a material. If the covering material is a second tow of composite prepreg or a woven prepreg, on heating to cure resin in the prepreg an elongate structural member with improved abrasion resistance can be achieved. This is especially so if the second prepreg is made of a kevlar prepreg. An example of a prepreg which may be used for the first stage of winding is a carbon fibre, Cuban fibre, PBO, an aramide or Kevlar (run) (poly(p-phenyleneterephthalamide)) prepreg. According to the present invention there is also provided a method of rigging a boat comprising the above described method and the step of attaching the elongate structural member via said two through holes as part of the standing rigging of the boat.

The method of the invention may be used to manufacture elongate structural members for use in tension (i.e. ties), in compression (i.e. struts) or to resist bending forces.

The present invention further provides a tie of composite material having two integral spaced apart through-holes and comprised of filaments set in resin.

This tie has the advantage over ties of the prior art of being both light, strong, creep resistant and having excellent corrosion resistance and has convenient attachment portions. The advantages of having the filaments set in resin are numerous. Most importantly the resin provides a degree of protection to the fibres - foreign matter cannot penetrate into the fibres so that mould between the filaments is substantially prevented. Furthermore, abrasion between filaments rubbing against each other is also substantially prevented e.g. salt from sea water. The resin means that no reliance is placed on friction between fibres to keep the tie wound together - no tight knots are required. UV protecting paint may also be applied to solid rigging which is not so easy with flexible rigging. The resin itself also gives a degree of protection in this regard. Preferably the filaments of the tie extend along the length of the tie and around the outer side of the through holes.

The present invention also provides an elongate structural member of composite material having two integral spaced apart through holes and comprised of filaments set in resin wherein said filaments extend along the length of said elongate structural member and around the outer side of said through holes. In this way, the filaments are orientated for minimum compromise of strength at the through holes which may be used as attachment portions. Also, maximum tensile strength of the tie/elongate structural member in the longitudinal direction between the through holes is achieved. If the filaments are substantially aligned between the through holes in a direction from one through hole to the other through hole, this results in maximum strength.

Preferably the filaments are windings around the outsides of both of the spaced apart through holes. This pattern of winding in a single loop has been found to give maximum strength.

If at least some of the filaments extend in a loop along the length of the tie or elongate structural member and around the through holes a plurality of times this also results in a stronger tie or elongate structural member because the resin does not have to take too much of the load when the elongate structural member is placed in tension.

The invention will now be described by way of example only with reference to the following drawings in which:

Figure 1 is a schematic view of a boat from its stern illustrating standing rigging; Figure 2 is a schematic illustration of the winding step of the method of the present invention;

Figure 3 is a schematic illustration of a further winding step of the present invention;

Figure 4 is a schematic illustration of the heating step in an oven of the method of the present invention;

Figure 5 is a schematic illustration of a further covering step of the present invention;

Figure 6 is a schematic perspective illustration of a metal ring which may be used in the present mvention; Figures 7a, b & c are schematic illustrations of alternative winding methods according to the present invention; and

Figure 8 is a schematic illustration of apparatus for pultrusion curing.

In the various drawings, like parts are identified by like references.

Figure 2 illustrates the first step in the manufacturing process of an elongate structural member of composite material which may be a tie. By composite material we mean a material which consists of elongate filaments or fibres held together in a resin matrix. A first mandrel 50 and a second mandrel 60 are provided in spaced apart relationship. These mandrels are illustrated as circles though they may be any shape. A reel of composite "prepreg" "tow" which is flexible is provided. The term "prepreg" is short for pre- impregnated and is used to describe a material which, when cured, forms a fibre reinforced composite; thus the prepreg includes filaments as well as resin which needs to be cured to form the desired composite product. The resin is already catalysed i.e. comprises two components the adhesive and the catalyst which need to be heated together to cure. The term "tow" relates to an un- wound and un- woven bundle of filaments orientated unidirectionally. Generally the filaments of a tow are not woven or twisted together to any great extent although this is not necessarily the case. The composite is preferably non-metallic and preferably has organic fibres which are preferably set in an organic resin. hi the method illustrated in Figure 2, a tow of composite prepreg 70 is wound around the outer sides of both of the spaced apart mandrels 50, 60 together by a filament winding machine such as a machine with a minimum of two axes of motion. The outer sides of the mandrels 50, 60 are those parts of each mandrel facing in a direction away from the other of the two mandrels 50, 60. In other words, the tow of composite prepreg 70 is made to form a single loop around both of the mandrels 50, 60. The tow typically comprises 1,000 to 24,000 filaments preferably about 12,000 and the tow 70 is wound in approximately from as few as 10 to as many as 1,000 loops around the mandrels 50, 60. A plurality of tows 70 may be wound around the mandrels 50, 60 together or in succession. A slight tension of 0-40 kN is provided in the tow 70. The precise number of filaments per tow and number of loops used are determined based on required strength of the tie.

In this way, at least part of the tow 70 extends between the two mandrels 50, 60 and those parts of the tow 70 are substantially aligned between the mandrels 50, 60 in a direction between the mandrels 50, 60.

Optionally, in order to bring the upper and lower windings (as illustrated in Figure 2) of the tow 70 together, the final end of the tow 70 can be wound around both of those windings along the longitudinal length of the tie and around the tie. This is illustrated in Figure 3 and the final winding of the tow 70 is illustrated as winding 72. This stage is not essential, the finally produced tie may be comprised of two spans. Preferably the tow is made up of long filaments such that each filament of the tow makes as least one complete loop around the mandrels 50, 60. In the preferred embodiment, each filament makes many loops around the mandrels 50, 60. In this way, the major contribution to the strength of the tie comes from the filaments rather than the resin of the composite. Preferably the composite prepreg is a carbon fibre composite prepreg. One such example is TCR Toray T700 12K UF 3369. Alternatively, the composite prepreg may be of a Cuban fibre, PBO (polybenzoxazole), an aramide such as Kevlar (rtm) (poly(p-phenyleneterephthalamide)). Other composite materials may also be suitable. The next stage in the method is for the wound tow 70 to be cured. This is accomplished by heating the tows to approximately 120°C at which temperature the resin in the composite prepreg cures. Once the resin in the prepreg has cured the tie is rigid. Typically the wound tows 70 are placed in an oven 100 (see Figure 4) still wound around the mandrels 50, 60. The temperature of the oven is then increased over a period of about four hours and once the temperature has reached 140°C that temperature is maintained for approximately six hours. The oven 100 is then allowed to cool and the tie may be removed. Preferably the tie is cured in a vertical oven such as the one illustrated in Figure 4. This allows the wound tows to be suspended substantially vertically such that the influence of gravity does not deform the tows 70 during the curing process. In this way, a stronger tie may be provided because the tows 70 are aligned between the mandrels 50, 60.

Preferably the wound tow arrangement 70 is suspended from the first mandrel 50 and allowed to hang freely under gravity or the tow is put in a small amount of tension by applying a small downwards force of 10-400N to the second mandrel 60 using a tension device 130. The force can be applied by weights, springs, screw fittings etc.. If a vertical oven 100 is used, because the ties can be long, the temperature of the oven 100 at the top can be substantially higher than the temperature at the bottom. In order to compensate for this, one or two fans 120, 122 are provided in the oven to blow hot air around the oven. The direction of the circulation of air is indicated by arrows 125 in Figure 4. The heat is provided in the oven by means of electrical or other heater elements 110. The tows are shielded from direct radiation from the heating elements 110 by wall 140. Top and bottom openings 160 in the wall 140 allow the air to circulate. The oven can be tilted for easy loading about a pin 155. Alternatively a crane can be used to load the oven. There are two other ways of curing the resin in the element. The first of these involves passing an electrical current through the filaments and/or resin which is effective to heat the resin enough to cure it. This is best done when the filaments are in a vertical orientation as described above in relation to curing in an oven i.e. hanging under gravity and/or under tension. Alternatively the filaments may be held straight by being supported along their whole length for example in a full length support mould. Electrodes are attached to the element adjacent to the mandrels such that the current passes through all or at least the majority of the element. The exact voltage and current suitable can be found by trial and error and depends on the length and thickness of the element as well as on the materials of the filaments and resin used and the surrounding environmental conditions.

The second alternative is advantageous because the machinery required takes up little space. It involves pulling the uncured wound prepreg through a die i.e. it is pultruded. Whilst the prepreg is in the die it is heated (e.g. by IR lamps, by contact with a hot die surface or passage of an electrical current) and thereby cured. Preferably the prepreg is pulled through the die vertically.

An apparatus for and method of pultrusion will now be described with reference to Figure 8. A pultruding die 200 comprises a die housing 210 in which an interchangeable die 220 is housed. The interchangeable die 220 is heated by heating elements 230. The heating elements 230 are electrical resistance heating elements in the illustrated embodiment which heat the interchangeable die 220 by conduction. Other forms of heating are possible such as radiation, for example IR lamps as mentioned above. In use, the die 200 is a two part die which can be clamped around the prepreg between the mandrels 50, 60. Generally the die 200 will be clamped around the prepreg close to one of the mandrels 60 and a force F will be applied on that mandrel 60 to pull the prepreg through the die at a rate such that the prepreg is cured whilst it is in the die 200. This ensures that gravity does not adversely effect the straightness of the filaments between the mandrels 50, 60 because only short lengths of the prepreg are cured at a time and during curing the prepreg is supported. The pultrusion method may be a continuous one in which the mandrel 60 is continually in tension and moving away from the die housing or can be a discontinuous one in which the element is pulled through the housing a bit at a time and is then brought to a halt to give the part in the die 200 a chance to cure.

As can be seen from Figure 8, the interchangeable die 220 has a tapered aperture 240 at the end through which the prepreg is pulled. This aperture 240 allows the windings which are separate from one another to be brought together before and held together during the curing process. This results in a solid rod which is advantageous if the element is to be used as a standing rigging component because it will have less wind resistance than a component with two members extending between the mandrels. However, the windings need not be brought together. The interchangeable die 220 is interchangeable so that the pultruding die 200 can be used for different thicknesses of element.

The ends of the element adjacent to the mandrels 50, 60 may be cured in one of several ways. The ends may be cured by being heated by radiation during the pultruding process (e.g. when they are close to the die 200) or the ends may themselves be clamped in a die which is moveable during the pultrusion process. In this case it may be necessary to ensure that the dies clamped around the ends of the element and the pultruding die 200 are well aligned such that no kinks or bends are present in the finished structural element.

In a solid rod tie such as one manufactured in one of the ways described, typically about lS -30 % of the weight of the cured tow is made up by the resin. The rod tie has the advantage that none of the filaments are damaged or broken by the provision or manufacture of the through holes as would be the case if the through holes were formed by drilling. For example, the path of the filaments remains smooth around the outside of the through holes and the filaments do not teπninate at the through holes in preference to elsewhere in the tie; the filaments are integrally formed around the through holes.

A tie such as the one manufactured in this way, is ready for use. If however, it is decided that higher resistance to impact or abrasion is required, a second tow prepreg or woven prepreg 80 may be added along and around the tie or only in areas of particular concern such as the ends. Figure 5 illustrates the case where a tow is wound longitudinally along and around the tie. Typically a kevlar prepreg tow 80 would be used for this purpose. Only a few windings around the tow are required such that the tow is completely covered. If only abrasion is of concern, the windings 80 may be in the form of a flexible polymer sheet which does not need curing. A prewoven sheath may also be used. If a composite prepreg is used the tie will need to be cured for a second time at elevated temperature or the second prepreg can be cured at the same time as the first tow of composite prepreg.

A heat shrinkable sock may be shrunk around the tie to give protection from degradation by UV light. Alternatively, the tie may be painted with a UV protectable paint.

A tie manufactured in the way described above, may be used in the standing rigging of a boat 10. Such a boat is illustrated in Figure 1. The mast 12 is supported by vertical elements 16 which are held away from the mast by spreaders 14. Between the outer most portion of the spreaders 14 and the mast 12 a series of diagonal elements 18 are also positioned. The tie manufactured in accordance with the above described method may be used as either vertical elements 16 or diagonal elements 18 of the standing rigging of a boat 10. The ties are manufactured to the exact required dimensions which may be from a few tens of centimetres up to several metres long. The ties are attached at the ends through attachment portions formed by the mandrels 50, 60. Typically at least one end of the tie is attached through a turnbuckle such that the tie can easily be put in tension.

With regard to the attachment portions, before winding of the tow 70 around the mandrels 50, 60, the mandrels may be coated or otherwise prepared such that after curing of the tows 70 they can be removed. In this way, it is possible for the ties to be manufactured with through holes at each end which allow the tie easily to be attached to the relevant structure. The integral nature of these through holes results in a particularly strong attachment portion because the filaments of the composite are not cut or abraded in the region of the through holes. In an alternative embodiment the mandrels 50, 60 are not removed from the tow 70 after manufacture and form an integral part of the tie. For example, the mandrels 50, 60 may be metal rings which can easily be attached by shackles or other aπangements to a boat 10. In a preferred embodiment the mandrels 50, 60 are constructed as is illustrated in Figure 6. The outer surface of the mandrels 50, 60 are provided by the outer surface of a ring 500. The ring 500 may be made of metal or composite. During the winding step illustrated in Figure 2, plates (shown dotted) are provided on either side of the ring 500 to help guide the tow 70 onto the ring 500. These plates may be removed either after the heating (curing) stage or before.

The ring 500 has an imier concave bearing surface 505 against which an outer convex bearing surface 515 of an inner member 520 bears. In this way, the inner member 520 can rotate relative to the outer ring 500. Attachment of the tie then occurs through an inner hole 525 of the inner ring member 520. Such a ring 500 and inner member 520 is available commercially and is sometimes referred to as a "rose bearing". Often a PTFE coating is applied to the outer convex being surface 515 so that the inner member 520 rotates more freely. Although generally a designer will attempt to ensure that forces in a tie are tension forces along the longitudinal direction of the tie, sometimes, for example whilst a boat 10 is motoring, vibrational fatiguing forces can be set up on the tie which are not aligned in the longitudinal direction of the tie. The aπangement illustrated in Figure 6 is designed to reduce these fatiguing forces by allowing some movement between the tie and the fixed structure to which the tie is attached.

Although the tie has been described in relation to use as part of standing rigging of a boat 10, the tie may also be used in other applications. For example, the tie may be used in structural engineering or the aeronautical or automotive industries. Alternative arrangements of winding of the tow 70 are also possible. Two such examples are illustrated in Figures 7a and b. In Figure 7a the tow forms a figure of eight pattern around the two mandrels and in Figure 7b there are windings illustrated around both of the mandrels 50, 60 together as well as individual windings around only one mandrel 50, 60. The embodiment illustrated in Figure 7b has the advantage that there are as many windings at the ends of the tie as in the centre of the tie. Figure 7c shows a tie in which extra windings have been made around the ends of the tie in the region where the tow 70 between the mandrels 50, 60 has been brought together. These regions can be the weakest part of the tie and such reinforcing helps to increase strength in this area. Alternatively a woven thimble may be placed over the ends of the tie. Of course, any combination of windings illustrated in Figures 2, 7a, 7b and 7c may be used in the manufacture of the tie.

Claims

CLATMS

1. A method of manufacturing a composite elongate structural member with two through-holes, said method comprising the steps of: providing two spaced apart mandrels; winding at least one tow of composite prepreg around the outer sides of both of said two spaced apart mandrels together, such that at least part of said tow extends between said two mandrels; and heating said wound tow between and around said mandrels to cure resin in said composite prepreg, thereby to solidify said tow as said composite elongate structural member with said through-holes being formed by said mandrels.

2. A method according to claim 1, wherein said composite prepreg is tensioned between said two mandrels during said heating step.

3. A method according to claim 1 or 2, wherein during said step of heating, said mandrels are positioned one above another, such that said part of said tow extending between said two mandrels is substantially vertically orientated.

4. A method according to claim 3, wherein during said step of heating said wound tow is suspended from the top mandrel of said two spaced apart mandrels.

5. A method according to any one of the preceding claims, wherein said step of heating occurs in an oven.

6. A method according to claim 5, wherein the said oven is elongate in the vertical direction and a fan is provided to circulate air in said oven.

7. A method according to any one of claims 1 to 4, wherein said step of heating is effected by passing an electrical current through said filaments and or resin.

8. A method according to claim 7, wherein said prepreg is supported during said heating step such that said composite elongate structural member is straight between said mandrels.

9. A method according to claim 1, wherein said heating step is effected by pultruding said uncured wound prepreg through a heated pultruding die.

10. A method according to claim 9, wherein said prepreg is pulled vertically through said pultruding die.

11. A method according to claim 9 or 10, wherein a tapered aperture of said pultruding die is effective to bring together windings of said prepreg.

12. A method according to any one of claims 8 to 11, wherein ends of said element adjacent said mandrels are clamped in heated end dies to effect curing.

13. A method according to any one of the preceding claims, wherein said step of winding comprises winding said tow in single loops around the outside of said mandrels, such that said tow extends along said structural member between said mandrels and around the outer side of said mandrels.

14. A method according to any one of the preceding claims, wherein at least some filaments of said tow extend between and around said mandrels a plurality of times.

15. A method according to any one of the preceding claims, wherein after said step of winding and before said step of heating, there is a further step of gathering together the parts of the windings extending between the mandrels by winding said tow around and axially along said parts between said mandrels.

16. A method according to any one of the preceding claims, wherein said mandrels are metal or composite rings and during said step of winding said tow is wound around the outer side of said rings.

17. A method according to claim 16, wherein during said step of winding, plates are placed on either side of said metal rings thereby to guide said tow onto the outer side of said metal rings.

18. A method according to claim 16 or 17, wherein said metal rings have an inner concave bearing surface against which a convex bearing surface of an inner member abuts such that said inner members are rotatable relative to and within said rings.

19. A method according to any one of the preceding claims, further comprising the step of covering said composite elongate structural member with a material.

20. A method according to claim 19, wherein said material is a second tow of composite prepreg and said method comprises a further step of heating to cure resin in said prepreg of said second tow.

21. A method according to any one of the preceding claims wherein said prepreg is of a carbon fibre, Cuban fibre, PBO, an aramide or poly (p- phenyleneterephthalamide) prepreg.

22. A method of rigging a boat, comprising the method of any one of the preceding claims and the step of attaching said elongate structural member via said two through-holes as part of the standing rigging of said boat.

23. A tie of composite material having two integral spaced apart through-holes and comprised of filaments set in resin.

24. A tie according to claim 23, wherein said filaments extend along the length of said tie and around the outer side of said through-holes.

25. An elongate structural member of composite material having two integral spaced apart through holes and comprised of filaments set in resin wherein said filaments extend along the length of said elongate structural member and around the outer side of said through holes.

26. A tie according to claim 23 or 24, or an elongate structural member according to claim 25, wherein said filaments are substantially aligned between said through- holes in a direction from one through-hole to the other through-hole.

27. A tie according to any one of claims 23, 24 or 26, or an elongate structural member according to claim 25 or 26, wherein said filaments are windings around the length of the tie or elongate structural member and around the outside of the through- holes.

28. A tie according to any one of 23, 24, 26 or 27, or an elongate structural member according to any one of claims 25 to 27, wherein said filaments and resin are part of at least one cured prepreg tow.

29. A tie according to any one of claims 23, 24 or 26 to 28, or an elongate structural member according to any one of claims 25 to 28, wherein at least some of said filaments extend in a loop, along the length of the tie or elongate structural member and around said through-holes a plurality of times.

30. A tie according to anyone of claims 23, 24 or 26 to 29, or an elongate structural member according to any one of claims 25 to 29, further comprising metal rings located in said two spaced apart through-holes.

31. A tie or elongate structural member according to claim 30, wherein said metal rings have an inner concave bearing surface against which a convex bearing surface of an inner member abuts such that said inner members are rotatable within said rings.

32. A tie according to any one of claims 23, 24 or 26 to 31, or an elongate structural member according to any one of claims 25 to 31, wherein at least some said filaments are windings around and axially along the said tie or elongate structural member between said two spaced apart through-holes.

33. A tie according to any one of claims 23, 24 or 26 to 32, or an elongate structural member according to any one of claims 25 to 32, further comprising an outer coating of material.

34. A tie or elongate structural member according to claim 33, wherein said material comprises filaments set in resin and filaments are windings around and axially along said tie.

35. A tie according to any one of claims 23, 24 or 26 to 34, or an elongate structural member according to any one of claims 25 to 34, wherein said filaments set in resin are a Cuban fibre, carbon fibre, PBO, an aramide, or poly (p- phenyleneterephthalamide) .

36. A tie according to any one of claims 23, 24 or 26 to 35, wherein said tie is a standing rigging component.

37. A tie according to claim 36, wherein said standing rigging component is a yacht standing rigging component.

38. A component according to claim 36 or 37, wherein said standing rigging component is a vertical standing rigging component.

39. A component according to claim 36 or 37, wherein said standing rigging component is a diagonal standing rigging component.

40. A method of rigging a boat comprising attaching a component of any one of claims 36 to 39 via said two through-holes as part of the standing rigging of said boat.

41. A boat with standing rigging wherein a standing rigging component according to any one of claims 36 to 39 forms part of said standing rigging.

42. A method substantially as herein before described with reference to and as illustrated in the accompanying drawings.

43. A tie substantially as herein before described with reference to and as illustrated in the accompanying drawings.

44. A boat substantially as herein before described with reference to and as illustrated in the accompanying drawings.

45. An elongate structural member as herein before described with reference to and as illustrated in the accompanying drawings.