as much trouble as for example putting a petrol nozzle in a fuel tank? or chaining down a lorry on a rogh trip?
#Idiot
It would be.
cars are going nowhere for an hour, all parked in fixed positions near to walls and ceilings and so on. Its up to the drivers to plug them in if they want a charge.
Given that they have an hour to charge, and the ferry is about 1000 cars, the worst case that they all limp in with dead flat batteries means they will need on 100Kwh batteries, about 100kw apiece. so in total they will need 100MW of charge power. It more likely to be less than half that. So 50MW
Obviously you wont get that from a 4000 bhp marine diesel setup, but te answer is to stick a reactor in them. Rolls Royce submarine reactors are of that sort of power output - 50Mw ore thereabouts its been estimated (classified)
I mean if we are going net zero ferries wont have DIESELS will they?
Although for cross channel they might have batteries!!