Most recently, several companies have begun making one-piece sails over a full-sized mold and doing their own Mylar-to-fiber binding, thereby bypassing the sailcloth manufacturers completely. At first glance it looked like this mega company had a tremendous advantage over small independent sail lofts like Schurr Sails.
The truth of the matter is that the sails are made from a series of Mylar panels that are cut on a plotter very similar to the machine at Schurr Sails. The panels are then glued together like any other loft would do and then put on a mold for fiber lamination. The "magic" mold is simply a workbench for the lamination process.
When these sails were first introduced in 1992, they were a big step forward in terms of light weight and shape holding ability. Since then, both Dimension and Bainbridge sailcloth companies have set the pace with better fibers, better fiber layouts and better lamination than could be achieved by any "in house" laminating process. The net result is that conventional triradial Kevlar/Mylar sails are now the lightest, fastest, and most durable sails available.
In 1983 it was Tape Drives, in 1986 it was Genesis, and in 1992 it was 3DL. Today, Dimension/Polyant has the D4 process and Bainbridge has developed their Load Path system. Schurr Sails continues to sift through the fads and deliver fast durable racing sails without tapping into the customer's life savings.
SPECTRA
A high molecular weight polyethylene, Spectra was introduced over a decade ago as a possible alternative to Kevlar. Spectra has the highest modulus of any fiber, except carbon, used in sailcloth but has seen limited application in racing sails because of its creep property, meaning that the fiber will permanently stretch when placed under high constant load. This stretch makes it difficult for sail designer to lock in the shapes they want. As a result, Spectra is viewed more as a performance cruising fiber where its excellent flex, UV and abrasion properties along with its traditional white color are perfect for large cruising boats where cloth strength and durability as well as weight aloft are considerations. Spectra is more expensive than Kevlar.