Although having become cheaper in recent years, the cost of laminate sails remains higher than that of woven sails of similar strength and size. Nevertheless, their improved robustness and durability means that they are seen with increasing frequency on performance cruising boats.
The main attribute of laminates is their ability to retain their shape, which of course makes them fast - particularly to windward.
In fact they'll delaminate and generally fall apart before losing their shape. This is exactly opposite to the way in which woven sails deteriorate, which stretch and lose their shape long before their construction becomes an issue.
You can probably expect three or four years of good service from laminates if you're a cruising sailor, but many competitive racing sailors budget on having to replace them every season. Ouch!
Laminate sail fabric is built up of layers of film, scrim and taffeta glued together under high temperature and pressure to form a light, strong composite sail fabric.
The film is a sheet of isotropic plastic, most often a Mylar extrusion, which has very low stretch characteristics in all directions, including the bias.
The scrim is a grid of large, unwoven, straight fibres which may be polyester, one of the HMPE varieties, or even more exotic fibres such as carbon. Scrims have very little stretch in the direction of the fibres, and are often bonded with other scrims of different orientation.
Taffeta is a woven fabric, most often polyester, that makes up the outside surfaces of the laminate, and is there to provide durability, UV and chafe resistance to the sail.
Laminates are lighter than woven sails and have a higher modulus.
As most of the scrim is usually orientated on the warp, the panels can be cut in long, narrow triangular shapes ideally suited to accommodate the stress patterns in a radially cut sail.
Sails built up in a series of bonded-together flat panels can only ever approximate - albeit very closely - to the computerized perfection created by the designer.
A molded sail is a laminate built up on a computer-designed female mould, and only then glued together under pressure with the designed double curvature accurately built in.
Molded sails are made in reasonably large numbers for one-design racing boats, which enables the mold and tooling costs to be amortised.
They can also be seen on large one-off sponsored racing boats, where they have completed round-the-world events without problem, removing any doubts as to their durability.
Manufacturers are striving to make inroads into the cruising market, but for the moment at least they remain prohibitively expensive for most of us.