Just an idea to help ward off griefers and encourage players to stop at islands rather than continuously murdering people (not that I'm against pvp by any means). Most everything else is limited, so why not limit gunpowder storage on your ship and allow it to be refueled either from barrels or from the shipwright? It could be based either on the ship size or # of crew members. If you limit the amount of ammo you can reload from your munitions box, griefers can't just sit there with a blunderbuss and blow your head off every time you spawn. Add in random spawn points on the ship and you might have a fair chance of fending off campers with a sword. Especially if, as a fresh spawn, you have ammo and they don't.