Plastics materials play an important role in the building and fitting out of modern sailing boats of all sizes and have been in common use for decades. For example, hulls can be made of glass or carbon fibre composites and polyester began to replace cotton for sails in the 1950s.
Sailcloth is designed specifically to withstand the stresses and strains of different weather conditions and uses. It may be woven or laminated with layers of film bonded to an open scrim to prevent the wind from blowing through. The choice of material from which sails are made is dependent on the intended use. This storm jib (1) is made from Dacron, a woven polyester fibre with an ultra-thin layer of polyethylene terephthalate (PET) to act as a waterproof barrier. Polyester is the most common fibre used for woven sailcloth and has good UV, fatigue and abrasion resistance and is relatively low cost.
Ropes, used to control the setting of a sail in relation to the direction of the wind, can be made from polyester, aramid,polyethylene, nylon and liquid-crystal polymer fibres etc., and are selected on the type of sailing being undertaken and the type of sails being used. They range from a basic polyester double-braid to high-tech constructions using different core to outer cover materials. Polyester ropes (2) are low cost, durable and UV resistant but tend to have more stretch than those made from materials like the super-strong polyethylene Dyneema® fibres (3). Dyneema® is known as the world’s strongest, lightest fibre, being 15 times stronger than steel. It is light in weight, hydrophobic, floats and is chemical and UV resistant, making it an excellent material for the production of sailing ropes. It also has good abrasion resistance through ratchets and cleats, and its firm, round profile aids handling.
Cleats are devices used to tie off ropes making them secure. There are various designs but all require reliable material strength to perform well. The open cleats (4), V cleats (5) and the spinnaker pole cleat (6) are all made from UV resistant polyamide. Where more holding power, easy adjustment and quick release is required a spring loaded cam cleat might be used. This example (7) is made from a carbon fibre composite on a glass reinforced polymer base. It is rigid, strong, lightweight and will not corrode or abraid ropes.