I wonder if you had a captain with an eyepatch, missing an eye, would he get pissed at subordinates saying "aye aye" to him all the time?
Another thing, what's the deal with all the hook-hands, peg-legs and eyepatches in the old-school nautical realm, when you hardly ever see those sorts of things in say, depictions of soldiers guarding forts? Those dudes weren't necessarily any less able to man the walls than a seaman to man the decks. Was it just not done? Did anyone with a serious wound put in a transfer to the maritime arm? "Sure! We can use 'im!"