My boat is a '97 Larson 206SEI with a Mercruiser 5.7L and an Alpha 1. The prop is an aluminum 14 1/4 x 19. I've never had a spare prop but I'm thinking I should get one. I thought since I'm buying an other prop maybe I would try a 4 blade. I'm fairly happy with the current prop. It's a Flo-Torq...