oldharry
Well-Known Member
I had a 10hp engine on a heavy 19ft and anything much over half throttle it just made huge waves - but didnt go noticeably faster.
3 things to watch for;
1. Trim - always a problem in a small boat, and under sail will slow you down, or even make the boat unmanageable if there is too much weight at the back end.
2. Is the outboard bracket strong enough? Brackets are rated for different HP engines, the stronger ones usually up to around 20hp, but lighter ones may be rated as low as 7.5hp, and will bend or break if you use full power. If the bracket wobbles with the engine on it, it is probably not strong enough.
3. Is the transom strong enough? If the bracket simply bolts through the moulding without any reinforcement , then probably it's not intended to take more than around 5hp. That being the case, unbolt the bracket and put a large wooden pad at least 25mm (2 x12mm sheets m/ply will do) to spread the load inside. Otherwise at full power the bracket bolts could pull through the GRP.
If it is directly transom mounted like on a dinghy, again the designer will have set a maximum HP, and if you want to go larger, some reinforcement is needed. Again a wooden pad is usually sufficient.
3 things to watch for;
1. Trim - always a problem in a small boat, and under sail will slow you down, or even make the boat unmanageable if there is too much weight at the back end.
2. Is the outboard bracket strong enough? Brackets are rated for different HP engines, the stronger ones usually up to around 20hp, but lighter ones may be rated as low as 7.5hp, and will bend or break if you use full power. If the bracket wobbles with the engine on it, it is probably not strong enough.
3. Is the transom strong enough? If the bracket simply bolts through the moulding without any reinforcement , then probably it's not intended to take more than around 5hp. That being the case, unbolt the bracket and put a large wooden pad at least 25mm (2 x12mm sheets m/ply will do) to spread the load inside. Otherwise at full power the bracket bolts could pull through the GRP.
If it is directly transom mounted like on a dinghy, again the designer will have set a maximum HP, and if you want to go larger, some reinforcement is needed. Again a wooden pad is usually sufficient.