Re: Why not use a boxer engine in a boat?
Is the OP positing that the flat boxer engine would sit much higher in the engine bay, thus allowing cooling water to flow downward, which alleviates the need to drain the engine, much as outboards do? Meh - ain't feeling it.
People have stuck rotary engines in boats. Jet engines can be found, too. You could jam anything in there you want, but for general-purpose boating, from fishing, skiing to running about, the venerable cast iron American engines with long blood lines have proven hard to beat for simplicity, durability, cost of production, ubiquity of parts/service and torque.
Yamaha and their Waverunner tech engines, now found in their sport boats, are able to make a game of it, usually when running their twins vs a single GM engine. All you need, see, is a massive company with proven, modern technology and to double the engine hardware and you can challenge 50-year old technology up to 50 MPH.
