Specialist

Specialist Crew-Members

Enemy ships might carry specialists which you can recruit for your crew. This happens automatically if you capture such a ship instead of sinking it outright, and specialists remain with you for the entirety of the game. They are not actually counted toward your crew totals, but they provide some very useful benefits

Barmaids can often tell you if there's a ship sailing nearby that has a specialist you don't yet have, so you can follow their advice to get them. You can also find them from just randomly attacking ships and boarding/capturing them. Smuggler ships are more likely to have a specialist on board, as are immigrant ships.

If you happen to capture Marquis Montalban at his hidden hideout, you will get all of specialists that you do not already have.

Carpenter
Carpenters are capable of making hull repairs at sea. At the start of each month, Carpenters repair 25% of the hull damage on all your ships. So if you are at 40% damage, the carpenter fixes 25% of that, putting your hull damage down to 25% (There is an error here. i.e. if you repair 25% of full hull then you are left with 15%. On the other hand if you repair 25% of damaged hull you are left with 30% damage).

Cook
Cooks prepare tasty meals at sea, which helps to keep crew morale up. This allows you to stay at sea for longer without the crew turning on you. Always a good thing.

Cooper
Coopers help you preserve your food in barrels. This means that Food takes up less space in the cargo hold, allowing for more 'useful' goods to be carried.

Gunner
Gunners train your crew in fast reloading. Your cannons will be ready to fire much quicker with the Gunner, and the difference should be evident immediately.

Navigator
Navigators increase the speed of your ships. This helps make voyages between ports less tedious and ship battles a bit easier to win. Combined with the Cotton Sails, the Navigator can help make your fleet a speedy force to be reckoned with.

Quartermaster
The quartermaster enforces discipline at sea. This helps keep the men in order and reduces the chance of a mutiny.

Sailmaker
The Sailmaker can repair your sails at sea. At the start of each month, Sailmakers repair 25% of the sail damage on all your ships, similar to the Carpenter.

Surgeon
Surgeons can treat injured crew members. In ship battles, half of the people lost during the sword fight return to duty afterwards. The surgeon does not affect the health of your character, just your injured crew.