I am not sure about the equipment the cruise companies provide for your situation. However, I have seen electric chairs being recharged on ships - usually in the passageways, although in-cabin charging may be available - and I have seen those in electric chairs tendering ashore and otherwise enjoying themselves.
I recall cruising on the Celebrity Century a few years ago and seeing two young men who were tetraplegic. They got around quite well. As I recall, they had to control their chairs via puffs of air.