My boat is an 18.5 foot Cobalt with a 205 hp 4.3L Mercruiser I/O. The dry weight is about 2,850 pounds. I currently use a 5-blade Ron Hill prop that is better for water sports than my 3-blade. RPMs at WOT for the 5-blade are around 4,700, which is near the top of the 4,400-4,800 range for my...