If it was a cable ferry, you could run one charged cable and pull the power off it it with a trolley and have electric thrusters on the boat. Need some battery backup for when the trolley jumps off the wire. (Actually it would probably use a pantograph like a train instead of an electric trolley wheel.)
I was watching the 1963 Japanese film High and Low. One of the settings is at Kamakura beach, where the kidnapper's hideout was, as well as the famous-to-Japan Enoshima Line, a single-car trolley line connecting Kamakura to Enoshima Island. In the dialogue was a reference to the difference between single-wire and pantograph trolleys:
"A trolley runs near the hideout."
"Three different trolley lines run through Kamakura. Maybe a specialist can tell which streetcar it is...."
"An Enoshima trolley?"
"Absolutely. l live near there. I've heard that sound a million times. It's an old single-wire trolley the others are all pantograph. Only the Enoshima line uses those old lines."
Unfortunately I can't find any photos of the Enoden as a single wire; it's been pantograph for at least the last 50 years.