> eventually larger ocean going vessels, which I predict will go diesel-electric before they go all electric.

Diesel-electric, particularly when using Azipods, is great when you need to do a lot of maneuvering in narrow spaces like ports. But for long-haul it's hard to beat the economics of a two-stroke direct drive diesel.

Maybe a hybrid concept for a long-haul ship would be using a direct drive two-stroke main engine, but the auxiliary diesels replaced by batteries?