The was a Wisconsin 2 cylinder that was made for marine use.. It was a
standard air cooled engine with a USCG approve flame arrester on the carb.,
elect. start and a marine reverse gear. (I can't remember the brand name of
the gear, it may come to me later and I will ammend this post.)

I had one of these in a 24 ft sail boat. It was new and came with the boat..

The main problem was the heat. The manifold and exhaust had no cooling since
the engine was air cooled. Hot as Hell, anywhere in the boat..

I think that even in an open boat you will have problems with the heat.
(station wagon effect) the air curls back into the cockpit area no matter
how fast your going.

In the Philippines, they use 10 to 15 hp air cooled engine in the motorized
outrigger fishing canoes. The operator will always sit forward of the engine
because of all the heat that comes off the engine and exhaust manifold.


--
My opinion and experience. FWIW

Steve
s/v Good Intentions