Captain
Responsible for the operation and livelihood of the ship. Organizes long-term planning and sets ship's goals. Able to make boastful claims that the crew will then have to back up...

First Mate & Second Mate
Responsible for the ship while the Captain is off duty. Direct completion of ship's operations and puts the orders of the Captain into action. 

Watch Officer
Lieutenant or Ensign in charge of one of the ship's field combat units. Doesn't have to be good, just has to be LOUD.

QuarterMaster
In charge of ship's logistics and physical property. Handy at building, repairing, and maintaining the ship. Responsible for transportation of equipment, property, and camp furnishings to and from site. Also responsible for the duty assignment and berthing of crewmembers. Knows the ship stem to stern and tolerates what the Captain puts her through...

Cooky (GalleyMistress)
Responsible for planning, transport, preparation, and cleanup of all meals aboard ship. Important to remember: responsible doesn't mean this individual has to DO all the work, just make sure it gets done. The Cooky can and should distribute the cleanup tasks to all able-bodied crew. 

GrogMeister
Prepares libations for the consumption of the Crew. We LIKE the GrogMeister... hic. Favorite brews: Arrogant Bitch Pale Ale, Dragon Stout, and a special batch of Vanilla Root Beer for the Cap'n...

Master Gunner & Gunnersmate
Responsible for operation of the Dog Watch (Ranged combat squad) on the field, maintenance of all Firearms aboard ship, and the training of new Gunners.

Bursar
Responsible for ship's funds. Produces monthly expense reports. Keeps the Captain from emptying the ship's coffers.

Yeoman
Communications and Public Relations. Responsible for maintenance of the ship's website, newsgroups, newsletters, emergency communications, etc. 

Salvage Engineer
Finds useful bits of equipment for the ship at unbeatable prices. "They were sinking. I don't think they were inna good position to be haggling..."