Mainsail Measurements
Hi Russ, Welcome to the Doyle Sailmakers Forum. To answer you first question, yes, we have a measurement for that asks for the distance from the back of the Mast to the Backstay at boom Height. This measurement allows our designers to figure in the distance to the backstay to allow for the most possible roach on cruising mains without hitting the backstay. Any full batten main or even a main with one full top batten will have a problem tacking through if it overlaps the backstay at all. Softer(less Stiff) battens can make it easier, but will not eliminate the problem in lighter breeze. There is a significant difference between Vectran and Kevlar. Kevlar is used primarily in racing sails. It is light, extremely strong, and virtually zero stretch. All properties that are good for racing. However Kevlar is prone to UV Degradation and Flex fatigue, not good properties for cruising. But in the overall life of racing sails this is not a tremendous deficit. Kevlar fiber also costs a bit less than Vectran Vectran, Has similar properties to Kevlar, but is not bothered by continued flexing, making it a good fiber for cruising. It is however prone to UV Degradation as well, so in the Cruising configuration, Taffeta backing(lightweight Dacron) is applied to shield the Vectran fibers from UV. This laminate fabric provides Strong low stretch sails, that are lighter than their Dacron counterparts, making it a good fabric for medium to very large yachts.
