What do you mean inefficient? Too many moving parts? or, just not designed well? I've seen some larger scale outdrives on some pretty quick boats.

As far as my intentions, I'm not trying to race. I want a boat that is sufficiently quick, but all out speed is not my goal.

I'm scratch building a 30" deep vee hull powered by a .15 engine. I'm having a hard time finding hardware that is A. Small enough B. looks good, and C. has the rudder centered behind the prop.

If that's not enough, did I mention I want a surface drive? Also, everything I do must be strong enough to accommodate a .21 engine at a later date. .....and, I'm not trying to break the bank either.

I'm open to any and all suggestions.