Originally Posted by pdqaltair
a. Unless you've figured out how to paint the inside of every passage you'll get growth inside. On inboards there are 2 differences; the passages are larger to allow for this; when the seacocks are closed there is no oxygen in the water and this tends to kill everything.
Seeing some outboards in the water all the time I have often wondered about the insides of the passages becoming plugged up? Doubtful that they could ever be un-plugged?
b. If something grows in there, you might just need a new engine. And something will.
c. Try this expereinment. Wrap some duck tape on a couple of blades, not floppy but not skin tight. Feel the vibration and note the loss in speed. It doesn't take much on a high speed (relative to inboard props) prop to desroy the flow.
I really don't think you want to do this. I'm not sayin' you can't, I'm just sayin' you'll be worse off.