The last couple of sails, I've wonder about the effects of reefing and just how much sail is out or not out. Thought about this and realized the rolling furler systems are nothing but right side triangles and the area can be calculated. Now before everyone jumps in here. Everything is approximate OK OK. This is a guideline. OK? The area of a triangle is area = 1/2 * base * height Since I really won't know the height I re-arrange the forumla to be area = ((base * base) * slope ratio)/ 2 which turns out to be area = ((16*16)/.3556)/2 = 360sqft Slope ratio = base / height Now with all of that said here are some tables showing the effects of reefing in the sails. I know that the jib is very inaccurate but what the hey this is sailing right.... Reefing for a H356 Sail measures Approx 45ft high 16 at foot This is for inmast furling system Main Foot Area Sqft Percent sail showing lenght 16 360 100% 15 316 88% 14 276 77% 13 238 66% 12 202 56% 11 170 47% 10 141 39% 9 114 32% 8 90 25% 7 69 19% 6 51 14% 5 35 10% 4 22 6% Jib Area % reefed 13 292 100% 12 249 85% 11 209 72% 10 173 59% 9 140 48% 8 111 38% 7 85 29% 6 62 21% 5 43 15% 4 28 9% Will entertain any thoughts about this. trying to arrange the tables after the post but doesn't work to well. Jim S/V Java