Amateur needs guidance. Experimental Build

Dave T, why not start another thread about your boats, or ask the moderator to move your post to a new thread?

 

That's not a boat you want to get planing. It would be too much of a nuisance keeping it balanced. Kind of like a unicycle. If you did get it on a plane and then moved to the side and threw it off balance, that would be memorable. I would even pay $5 to see it happen.

With the engine, if you can rig up a drive train where you could use one of those centrifugal clutches, that would solve forward/nuetral problems for about $69. Lawnmower transmissions can give you a range of speeds plus nuetral and reverse. Gear it all so the reverse and 1st or 2nd gear are what you use.

A huge problem with lawnmower engines is noise. Even with car mufflers and an underwater exhaust, the engine itself might make a good amount of racket.

For the stern tube and stuffing box, I've seen photos and a description of the whole works made from regular plumbing supplies.