The Hellfish is only briefly mentioned in the Savage Tide adventure path. It essentially belongs to the loser pirates of a tiny little island near the Isle of Dread called Rat's End. While the action doesn't really take place aboard the ship, I didn't want to get caught without a deck plan in case combat went there.

Described as the pirate's only seaworthy ship, its design was left to me. I decided to make it a 20-year-old barnacle-encrusted two-decker fantasy brigandine designed to move men and a few slaves or prisoners but fast. The party did indeed end up capturing the ship after dealing with the pirates who made landfall to attack the town of Farshore.