I don't know much about the subject but if you can do it to a small generator and a $100.00 adaptor kit you should be able to switch almost any 4 cycle engine to propane. We have the propane kit on ours and can run gasoline, propane & natural gas. We keep a couple standard propane tanks around for emergency purposes. (Mostly for the BBQ) Seems to me that unless the outboard runs on gasoline also it's a dumb idea.