haha, Pirate Manual of Conduct, I love it :) (Page 1: Rape, THEN pillage!)

Anyway...perhaps fleshing out why the pirate gets marooned would point you in a good direction. How does it connect to him violating the pirate rules? Is he trying to clear his name in "straight" society or among pirates? Maybe his pirate crew is scandalized at his behavior and mutinies, forcing him to walk the plank and swim the last few feet to the island.

Since the pirate is forced to be on the island, I think it'd be neat if the old man was on the island by choice. Old man could be feuding with his brother or his wife or something, and decided to go be a hermit to avoid having to deal with all the squabbles. At which point you'd have to somehow convince him to go back to the mainland and patch things up. (Maybe your pirate happens to know his family, and you tell him his daughter recently had a baby and he really ought to go meet his grandson.) Of course the old man has a boat stashed somewhere on the island, indicating he's not really as much of a hardass as he likes people to think.

Then on the way to the mainland, you could have an encounter with a sea monster, other pirates, a storm, something like that, in order to get a good mix of thoughtful stuff & action. I'm picturing a scene where the old guy walks into the old house he used to live in, almost buried under seamonster steaks, whistling merrily and pretending it's just a normal day. :P