I was initially responding to a post stating that there were many all-electric ferries, and my point was that there were none (operational) of a size comparable to WA state ferries. https://news.ycombinator.com/item?id=42197763

There are many large hybrid vessels; notably, this has been common for submarines for a very long time. The largest currently operational diesel-electric (hybrid) submarine seems to be the Chinese Qing-class, of ~3800 tons surfaced displacement.