Remember the guy 4 or 5 years ago that put a Honda motorcycle engine in a 3 point hydro and designed a surface drive for it? It's me. Now I've got another brain child to ponder. I have a 9 foot jet ski hull and would be using a Honda civic 4 cly. engine. This is where it gets dicey. I want to drive it with a prop but on a self trimming design. I thought that a prop shaft with a universal joint at the engine and the shaft being mounted to an A shaped arm to allow the shaft to have vertical movement. A spring mounted to the A arm will force it down to 12 or so degrees. When gaining speed a horizontal fin mounted to the shaft tube would force the shaft up to 9 or 10 degrees to allow the prop to break the surface. (surfacing prop needed). The shaft will be over driven by 15 or more percent. Steering will use an outboard mounted rudder. Now that you're done laughing,,,,,I built a bulldozer out of a lawn tractor, and converted a 16 ft outboard boat to V8 stern drive. This sounds doable.