Charlie Stross (npub1yac…la7e) Dan Jacob (npub1mcz…dr5f) The nice thing about container ships is that once you've finished loading them, you have a massive flat area onto which you could unroll solar panels.
You can also have container batteries.
How much battery storage you'd need on board and whether covering the top of the cargo with rolled out solar PV would provide enough to keep it going is not something I've done the maths on, but add wind propulsion and solar power with much of the existing fuel and ballast replaced with batteries together, and it's possibly feasible.