This is not historically accurate, but has been bastardised from later periods for use in a game context. Medieval crews were much less structured and used merchant customs because no English king maintained a permanent military navy for any length of time. Henry V built a score of ships to maintain ownership of the English Channel and to wage war against France, but for large periods of their time they were leased out to English or Venetian merchants for commercial voyages.
Fleet Officers:Captain: Sometimes familiarly known as the Skipper. Overall command of the ship. Not quite absolute authority while at sea, but as near to it as makes no difference. Holds command directly from the Admiralty, and has previously served as a "No. 1". The Captain customarily takes a quarter of all prize money, the rest being shared equally among the Lieutenants and Warrant Officers. Captains are routinely re-assigned to different ships at the end of a tour of duty.
1st to nth Lieutenant: (pr. Leftenant) In charge of raising crew, sorting watches, leading men into action. These officers assume command in order of seniority if the Captain dies ("No. 1" routinely commands the off-watch). Lieutenants are over the age of 21, have served at least 2 years as a Midshipman, and have passed an examination by the Admiralty on their knowledge of seamanship, navigation and combat at sea. Entitled to one share of all prize moneys.
Midshipmen: Also known as "Snotties". Teenagers receiving both informal and formal education on seamanship and navigation. Usually recruited from the ranks of gentlefolk and wealthier merchant families, since a fairly high level of basic education is required.
Warrant Officers:Navigator: A highly trained specialist, who closely guards his own personal Rutter (route book) as well as updating and annotating the ship's charts. In game terms, he is also a priest of Esprayenna with temple skills and a concern for the souls of the crew.
Boatswain: (pr. Bowsun) In charge of boats, rigging and sails.
Burser: In charge of cargo and provisions. Customarily boosts income by running an onboard shop for supplementary provision.
Carpenter: In charge of the hull, fittings, pumps and anchor. Is required to have gained a full qualification on land.
Surgeon: In charge of all medical matters from toothache to emergency amputation. Training is given by the Torian temple, but surgeons are not Physickians and certainly not part of the qualified priesthood.
Master at Arms: In charge of signalling, fires and discipline.
Note that Warrant Officers held rank "by warrant" from the Captain, but were highly experienced and usually better paid than the Lieutenants. Lack of promotion prospects, or a preference for the specialisation, very often led an experienced Lieutenant to become a Warrant Officer instead. Most warrant officers had a Mate who was their second in command and took the off watch.
Quartermasters: One for each watch. Deal with stowage and actually steer the ship.
The Cook: A major fire hazard who reports directly to the Master at Arms.
Carpenter's Crew: Often required to ply their skills under battle conditions.
Ropemaker and Sailmakers: Report to the Boatswain.
The Crew:Classified as Landsmen for the first 2 years, then as Seamen, then as Able Seamen at the discretion of the recruiting No. 1. The classifications affected pay.