What the *$^% is a: Quartermaster?

A Quartermaster enforces discipline aboard ship; sometimes the same job as the Bo’sun. They were elected by the crew and were the second most powerful men aboard ship and had veto power of the Captain's orders as long as they were not in the middle of a battle.

Quartermasters led raiding parties onto other ships and some Quartermasters, notably Captain Jack Rackham succeeded to command their own ships and become captains in their own rights.

What the *$^% is a: Cabin Boy?

A Cabin Boy is a boy usually between the ages of six and twelve who tends to the ship's quarters and runs errands aboard ship. These boys were usually onboard as apprentice sailors, and often received an education in navigation or other important seafaring skills.

These boys may have been powder boys when they were younger.

Cabin Boys feature prominently in many folk ballads and stories like Treasure Island.

What the *$^% is a: Cooper?

A Cooper

A cooper is person who makes barrels. Barrels are extremely important aboard ship because they hold fresh water among pretty much everything else. Having a cooper aboard ship means that you can fix these barrels and make more if necessary.

While this skill probably wasn't a skill that kept a person busy all the time, being a cooper was definitely enough to make a man valuable.