Well, the good news is that the PC's are probably not going to captain the ship, and I don't expect any really large-scale ship-to-ship-to-ship-to-ship battles. I have Seas of Blood, and I'm thinking to pick up Seafarer's Handbook. What Im really looking for is information about "life at sea," weather and hazard charts, good wandering monsters, encounters, information about trading, raiding, food, diseases, different kinds of ships, equipment on board, sailor-type weapons and skills, stuff like that.