We have a folded-up “rope” ladder at the stern with a short trailing lanyard. If someone falls over the side and is sufficiently conscious, and strong, they can tug the line and the ladder will unravel.
I’ve fitted an engine-stop – can’t remember the make, sorry; Scandinavian, I think – which consists of a wireless receiver on board and a transmitter which I wear round my neck. I can’t start the engine till I’ve activated the receiver and battery-powered transmitter (the receiver is wired to the engine-stop solenoid). If I fall overboard (into water), or am more than 30′ from the boat, the receiver can’t pick up the transmitter’s weakened signal, so the on-board receiver stops the engine.
Of course, this has no effect when SAILING.
We haven’t yet worked out how one of us can retrieve the other of us if one of us falls off, especially if the one who falls off is unconscious. But we DO have a clip-on rigid boarding ladder which has fittings at the boarding sections on both side of the boat, courtesy of the previous owner, Dr Vic.