We have a tunnel hull Jon boat, 15' where the tunnel runs the entire length of the boat. We just got a 24 hp Honda Beavertail. The motor is mounted perfectly (c-clamp) but it hardly pushes the boat. We think that the turbulence from the tunnel, the air and water wash is keeping the prop from being effective. The motor will push the boat at idle but give it any throttle, it doesn't hardly move. Does anyone have any suggestions to fix this problem?

How deep is your tunnel? You should be able to see if the wash is affecting your prop.

I would check the prop first either way and lower skeg. You gotta have something slipping somewhere. Take a pipewrench and try to tighten the prop if you cant bottom it out against the rear jam nut the threads on your drive shaft are stripped and your prop is slipping.

Could be a worn prop, is it bumpin the rev-limiter at full throttle?

Work got in the way this week. I swapped motors and put the Beavertail on another 16' Jon boat. It still does not push the boat. I checked the prop, it is not slipping. I have no idea why this motor is not working. Is there something I am missing here? It makes the boat move in idle but the second I give it throttle it quits moving.

Is the prop worn sharp and smaller than original diameter?