sail area/(disp/64)^.666 This is a ratio of power to weight, calculated using a 100% jib. Most monohull designs range between 16 - 18. Racers can be much higher, motor sailors lower. We want a cruiser with enough power to sail well but not so much that the crew is fatigued by constant sail changes or worried about having a fragile oversize rig. I selected 14 as the minimum, 15 - 17 optimal, and 18 maximum.