Mainsail Roach Amount
Jim, In general race mains should be built to maximum girth in order to maximize the square footage of the sail. Sail area up off the water is the most efficient in terms of producing power. You will notice a big difference in light airs when comparing mains with different amounts of roach. In heavy air conditions it is relatively easy to "depower" a full-size mainsail by flattening and twisting the sail. Most non-race boats do not need the extra power since they sail with relaitively light crews. Also it is easier to tack and jibe a main that does not overlap the backstay very much if at all. Therefore for most cruising and day-sailing applications we recommend a modest amount of roach. The exception to this are boats such as some Hunter boats that are designed to have a balanced sailplan that includes a mainsail with a large roach even for cruising. If you have one of these rigs it is best to stick with a large roach mainsail. Bill Colombo Doyle San Francisco
