If you could plumb steam to the engine you might be able to do this, but
> there's likely no way to put reasomable power in an outboard engine with
> the boiler requirements.
There have been a number of successful designs that have accomplished this goal. You won't get 150hp out of it, but certainly enough power to move a s mall skiff at a decent speed- 8hp or so. Traditional boiler designs are too heavy, but the Serpollet monotube works quite well. Check out Wally Mounst er and Terry William's designs.