How fast can a 115 hp mercury go on a 15 ft fiberglass boat?

Question

How fast can a 115 hp mercury go on a 15 ft fiberglass boat?

Answer 1

Depends completely on the hull.  Some older 80's speed hulls (checkmate/baja/hydrostream)typically with WIDER BEAM designs had very THICK transom mounts that were rated to support up to 90 hp engines. Now engines at that time for 90 - 40 often used the same motor heads bored to different sized cylinders for more horsepower.  That being said, if your 15 ft can handle the weight, it may not be able to handle the power, if you start to porpoise at 50mph you could EXPLODE your boat, Deep six your boat like a submarine, or the motor could fly right off the back of the transom and end up in your lap!  Be careful, this experiment could end badly for you.