You can convert a radiator based open frame genset to keel cooling
fairly easily, but that isn't the end of the story.
You then need to rig a dry stack exhaust
which requires an air cooled chimney (for lack of a better word) to pass the exhaust
hose through. And then you still will not have a water
cooled exhaust manifold. That means a lot of extra (and dangerous) heat in the engine
These are some of the reasons why marine
generators cost more, but are worth it.