Lots of variables here, but for comparison I have a 31'
Beneteau displacing about 7500 lbs that cruises at 6.25 kts at 2600
RPM (80%) with an 18HP
Volvo using a Flex-O-Fold. So I
cruise at about 86% of my 7.2 kt.
hull speed. The Flex-O-Fold was around $600.00 and a fraction of the cost of most alternatives despite the obvious quality, and was one of the best value investments I have made on a
boat I have owned since 1993. We experience higher speeds under both
power and sail than the original fixed 2-blade prop, without loss of performance in reverse responsiveness. Maybe a touch more prop walk.