The biggest problem with Electric is the battery weight, so it makes sense.

Ships deliberately use cheaper, less energy dense petroleum products (heavy fuel oil), for pretty much the inverse reasons why airplanes use kerosene.

Not really, kerosene is pretty close to heavy fuel oil on density.

Planes run on kerosene because it's universal enough, hard to run them on heavy fuel, and there is issue with high emission of the HFO over population centers which isn't as much of a problem in middle of sea