The best use case for electric is things that see the high use. Cars that do lots of km every week, delivery vans and trucks, rubbish trucks, buses, should all be high on the list. There is a higher up front cost, but with savings on fuel and maintenance the payback is rapid.
A typical yacht with an existing diesel does very few hours per year and is not worth swapping to electric, even though the efficiency below hull speed would make them easy to run.