what would happen if you ran a 15 hp long shaft motor on a boat that is supposed to have a 15 hp short shaft, small aluminum boat about 14 ft long? much thanks

Not a thing, except you will lose a little ability to run in shallow. There is slightly more drag by the extended lower unit, but it's not usually an issue.

You will most likely get some spray up the back of the boat when you are up on plane.

I have also seen people add a piece to the transom so the motor is mounted a bit higher.

I recently inherited a 15 HP long shaft Honda and am looking for a small 14' aluminum to put it on, so I expect to be in the same "boat" as you. I'll be interested in hearing how it works for you.

Jeff

It won't have any effect on the motor, but the performance will be disappointing in all likelihood.

I don't think you'll like the results. The long shaft has plenty of drag, and if the motor is kind of marginal for power (and it may well be on a big 14' boat) then you'll probably be disappointed. My gut feel is that you will have trouble getting on plane. You will also throw a lot of water.

The suggestion that you raise the transom on your boat is a good one. You could do it easily enough with some 2x6 or 2x8 stock bolted across the transom and reinforced with plate and angle braces through-bolted in place. ( I'm thinking I would put a safety chain on the motor the first few times I went out..)

The upside is that by raising the level of your transom, you'd have a more seaworthy boat.

Good luck,

Keith

been there done that. nothing that you will really notice, except for that sallow water thing, I would tell you don't buy a short shaft motor because if you get a bigger boat or need a kicker for a boat you won't be able to use the short shaft. Good luck!

thanks for the great feedback, my buddy showed me this deal in bass pro shops that is for making the transom deeper and solving this problem.

Jeff the motor I got is a honda too so I guess we are in the same "boat". I'll let you know how it works, gonna get on this project ASAP, tightlines