A recent article, says that a 15 inch standard three bladed prop increases resistance by 22kg. This can account for 35% of a hulls resistance on "some" boats, okay perhaps a slippery racing hull with fin and spade rudder and with a total resistance of 63kg. The same article says that a three bladed folding prop only increases resistance by 3.2kgs so to fit one would reduce the total boats resistance by about 30% a fantastic improvement! I have a Warrior 35 with long keel. I have no idea what a Warrior 35´s total resistance in Kgs is (perhaps someone can tell me) but it must be loads more than 63kg. If it was say 200kg then my prop would account for 9% of the total resistance and so to swap for a folding prop at 1.6% my benefit would only be 7.4% If my calculations are correct I may not even notice the benefit so is the whole excercise worth it. I would apreciate any advice I can get on my calculations and your experience in fitting a folding Prop to a long keeled boat. The model I have in mind is Bruntons varifold.