Background art A reinforced sail having threads running in the direction of principal stresses in which the threads are laminated to a film material is described in US 4 708 080.

In that patent, the reinforced sail has one corner reinforced by a headboard. A sail headboard of the known art is described in US 6 371 037. Usually, a sail head- board is formed by two perforated triangular metal plates arranged on either sides of a head end of a mainsail, and attached to the head of the sail by through rivets, se Fig. 9 of US 6 371 037. At the top end the metal plates are connected to a halyard, said halyard being a rope or wire used to hoist the head of the sail to a sheave near the top of the mast, and to maintain it there while under sail.

A first problem related to the headboard comprising two metal plates riveted to the sail is deformation of the sail around the rivets through the holes in the sail.

The holes are often the initiating points for tearing of the sail.

A second problem is the weight of the metal plates. Because of being arranged far up in the mast, far from the gyration centre of the rolling sailboat, the added weight of the metal plates is undesirable.

A third problem is the sharp transition from the flexible sail to the stiff metal plate, giving rise to shear forces along the junction line. This problem will worsen due to shear forces arising when there is a forward force having a direction towards the luff and the mast from the sail acting on the headboard during most wind conditions.

Short summary of the invention A solution to the problems above is presented by the invention, which is a sail headboard, clew board or tack, for forming a reinforced transition between a

sail and a halyard rope or wire, clew or tack rope, or similar, comprising the following features: A first and a second broad web, here called a"headweb"having matrix impregnated area portions arranged adjacent each other, and each headweb having a sewing portion continuing outside at least one side of said impregnated portions, said sewing portion being flexible and less impregnated or non-impreg- nated, said sewing portions for being arranged on either sides of a sail and fixed to said sail.

The headweb is reinforced at least by comprising tension fibres to be aligned with local tension lines or fibres included in said sail.

In an advantageous embodiment of the invention, the headweb comprises a transversely reinforcing rigid layer arranged so as to cover at least a portion of said matrix impregnated area portion. The reinforcing layer will prevent the head- board from bending or buckling the top of the sail. This will maintain the desired sail area near the top of the mast even during strong wind loads and thus strong loads on the headboard.

In an even more advantageous embodiment of the invention, the trans- versely stiff plate layer comprises transverse fibres having a direction athwart of the direction of said tension fibres, for providing improved bending moment resistance to said sail headboard.

Another advantage of an embodiment of the invention is that said head- board is provided with one or more elongate web bands for being aligned with local tension lines or fibres in said sail, said web bands extending beyond said sewing portion of said headweb, and further being arranged for fixed attachment to said sail, for increasing the extension of the force distributing area of said sail further from said headboard.

A further advantageous embodiment of the invention comprises said sewing portion arranged for being fixed to said sail by sewing. The sewing attachment of the sail to the headboard assures an even distribution of forces between the sail and the headboard, while also being flexible. A not insignificant advantage is that the sailmaker may use his ordinary sewing tools for attaching the headboard to the sail.

Short description of the drawings The invention is illustrated in the attached drawing figures, which are made for illustrating the invention, and shall not be construed so as to limit the invention, which shall be limited by the claims only.

Fig. 1 illustrates a headboard of the known art.

Fig. 2 illustrates a headboard according to the invention in a horizontal elevation view from a port side of the sail.

Fig. 3 illustrates a vertical cross-section along a line A-A indicated in Fig. 2.

A description of a preferred embodiment of the invention A headboard of the known art is illustrated in Fig. 1, and can have two roughly triangular metal plates 1 arranged on either sides of the head end of a sail 10, with rivets through holes in the plates and the sail. Also known are web bands 6 having one end extending from one side of the sail, looping through recesses 7 in the headboard plates, the other end running back along an opposite side surface with respect to the first end, all sewn to the sail. The web bands 6 may be arranged as a forward web band 62 extending vertically to reinforce the sail against vertical forces, and a rear web band 64 to reinforce the sail to take loads from areas in the sail nearer to the leech, further from the luff.

A sail headboard according to the invention, which may also be a corresponding clew board or tack, for forming a reinforced transition between a corner of a sail 10 and e. g. a halyard rope or wire 9, clew or tack rope, or similar, is illustrated in Fig. 2, and comprises the following features: a first and a second broad web, called a headweb 8, having matrix impregnated rigid area portions 81 arranged adjacent each other. Each headweb 8 continues into a"sewing"portion 82 outside at least one side of said impregnated portions 81. The matrix impreg- nating the impregnated area portions 81 may be polyethylene PET or a similar thermoplastic material. The headweb 8 may be a broad band woven of aramide or a similarly strong web of a desired material. The sewing portion 82 is flexible and less impregnated or non-impregnated. The sewing portions 82 are made for being arranged on either sides of a head end of the sail and fixed to the sail 10. The

advantage of having one sewing portion for each side of the sail is that during tension, the sail will experience less local twist or shear deformation.

The sewing portion 82 is, as the name indicates, arranged for being fixed to said sail 10 by sewing by means of sewing yarn 11. The sewing portion 82 may also be fixed to said sail 10 by means of glue.

The headweb 8 is reinforced at least by tension fibres 12 to be aligned with local tension lines or fibres 112 included in the sail 10. These reinforcement fibres may be the main force direction of the headweb web itself.

In one embodiment of the invention, a polyethylene film 84 is arranged on the outer surfaces of the headweb 8 to protect the headweb aramide from ultra- violet radiation.

In a preferred embodiment of the invention, the headweb 8 comprises one or more transversely reinforced rigid layers 1 arranged so as to cover at least a portion of said matrix impregnated area portion 81. The rigid layer 1 may be a carbon fibre reinforced PET matrix arranged on either side of the headwebs 8 and impregnated in the same process by PET. This layer 1 is illustrated in the vertical section of Fig. 3.

In a preferred embodiment of the invention, the transversely stiff plate layer 1 may comprise transverse fibres 14 having a direction athwart of the direction of said tension fibres 12, for providing bending moment resistance to said sail headboard.

In a preferred embodiment of the invention, the headboard is provided with one or more elongate web bands 6 for being aligned with local tension lines or fibres 112 in said sail 10. These web bands 6 extend beyond said sewing portion 82 of said headweb 8, and are arranged for fixed attachment to said sail 10, preferably by sewing using sewing yarn 21, as indicated in Fig. 3, but also by using glue, for increasing the extension of the force distributing area of said sail 10 further from said headboard.

For connecting the upper portion of the headboard 8 to the halyard, a metallic eye insert 71 for a shackle connecting further to a grommet in a halyard may be arranged in a hole through an upper portion of the rigid portion 81 of the

headboard 8. In a preferred embodiment of the invention the webs 6 may loop through the eye insert 71.

In a simpler embodiment, for e. g. a lighter sail, the webs 6 may extend above the headboard 8 and loop through a steel ring.

The headboard 8 may be manufactured by vacuum consolidation of fibre reinforced thermoplastics plastic composites according to other patent applications pending, belonging to the applicant. This technology allows mixing of different fibre types and matrix types in one moulding batch.