If the only person who can move the boat was laying on the floor in a bad way,
That's madness. You need two confidant crew who can move boat.
So all you couples the one who can't steer..............learn.
Of course the application form is a lot less to fill in when claiming under special rules. Nobody wants to be in that position though.
Colin think this through very carefully. Your wife is losing her sight before you have stepped aboard. What health issues would restrict yourself in helping your wife.