Originally Posted by 9D280
I would check your prop / engine angle etc first - I've taken those fins off two boats so far - all they did for me was scr*w up the handling at speed - the first boat nose dived spectacularly and become really unstable above 3/4 throttle because they gave too much lift (and that was with the engine fully raked back on the rear pin), the other took an interesting lean to port as one was lifting slightly more than the other!
I really don't like them based on experience, but there's people out there swear by rather than at them! Just my 2p's worth.
I'm sure there are variables that come into play but having used fins on a 4.7m Searider/50hp for ten years and before that on a 15hp Zodiac SIB, never did I experience anything other than greater ease in getting up on the step, greater stability at speed and a damn fine place to put one's foot while re-boarding the boat in the water.