While you could certainly do it, you would have to deal with the availability issue previous posters mentioned, plus seperate
tanks, preheaters, etc. if you're handy and don't mind being dead in the
water fixing things at
anchor or
dock, go ahead. You would have to be a real enthusiast to make it
work I think. If you have a restaurant, and it makes sense not to sell it, that's another story! Still with barrels/tanks of oil, you will have a bit of a mess on your hands.
As far as biodiesel goes, I don't burn in in my
boat but I burn a ton of it at the farm. I've had to change fuel lines in my truck and older combine, and I've got a bunch of late model green tractors that tolerate it fine. I never let it sit for any amount of time, as it is hydrophilic and also eats at any natural rubber in the fuel system. Seems like a bad fit for a
boat and you won't find it on the fuel docks anyway.