I have one on a smaller motor. I believe they make to sizes. On my smaller boat I installed one it works very well. The boat is a 11 foot zodiac with plywood floors the motor that came with it when i purchased it used was a 25hp yamaha. My friend that originally purchased it used it for buzzing around on nice days. you can actually knee board behind it. The boat only weighs 125 pounds and motor about the same so a pretty good weight to horsepower ratio . At idle it was just to fast unless fishing for silvers in the salt. I went out and put one on and it really slows it down to the point that I actually run it between being up and down. I found with it in the locked down position to get to a slow trout fishing speed you had to have the motor up in a high idle. So now i put it in gear then pull the rope to let the springs take it down into position. It drops half waydown and wont lock because of the prop thrust pushing it out. Sure beat replacing the motor . I have not had a problem with it at all. I have had the boat for about 10 years with it on and would get another one .