I believe I had a stock prop that was on it before. Numbers were on unreadable. I believe a stock prop is a 9.25 x 9p. I felt.like the motor was revving all the way to leak power so I put the 7p on it and a little tach. I had to move forward in the boat with a tiller extension to get on plane. Got on plane once I moved forward in the boat and reached a peak of 4300 rpm. The boat is a Martindale.