Bob, the purpose of the foam luff is...
to help maintain the shape of the genoa when it is "reefed" (partially furled). With roller-furling you can reduce the sail area by partially furling the genoa rather than making a sail change... a good solution for someone who hasn't the crew power or inclination to go forward when the wind speed changes. The sail when partially furled isn't as efficient as a hanked-on sail of appropriate size, but using the foam luff helps the partially furled sail maintain an acceptable shape and efficiency. Without the foam luff the sail would roll up tighter at the top and bottom of the luff resulting in a baggy sail shape and loss of power. It is a compromise, but one that makes sailing more comfortable for those who single-hand (as I do a lot) or prefer the convenience of roller-furling. Tom
