The Operations Department is considered the "line" department of a merchant space craft. Personnel of the operations department oversee all active space operations of the vessel, to include space navigation and onboard administration.
Licensed officers comprised a hierarchy of "mates" who also serve as the chain of command for the vessel, answering to the Ship's Master. The First Mate of a merchant craft fulfills the regular duties of a space vessel Executive Officer.
The Engineering Department oversees the operation of a merchant vessel's engines. Licensed officers of this department include the Chief Engineer as well as a First and Second Engineer. On larger vessels, Warrant Engineers may be appointed from rated Engineer's Mates.
On most merchant vessels, the Chief Engineer also holds certain line qualifications and may take command in the event of an emergency or other crisis.
The Supply Department serves as a mission essential part of any merchant vessel's organization. In charge of all onboard supplies, include any cargo which the merchant vessel may be carrying, the Supply Department is commanded by the ship's Chief Purser, assisted by at least one First Purser and several Second Pursers.
Warranted supply personnel are known as "Storekeepers", divided into a both a junior and a senior (chief) level, obtainable through examination and appointment.
Licensed communications officers command a merchant vessel's Communications Department, in charge of all onboard communications equipment including both conventional and subspace radio systems.
Warrant communications personnel are known as "Radiomen", divided into both a junior and a senior (chief) level.
The Ship's Services Department is the smallest of all the merchant marine shipboard organizations; on some smaller vessels, the function of the Ship's Services Department is overseen by the Supply Department.
Primarily concerned with custodial upkeep of a merchant vessel, as well the onboard preparation and storage of food supplies, the Ship's Services Department is overseen by licensed Stewards, assisted in their duties by Warrant Stewards and Steward's mates.
Most merchant freighters and cargo vessels carry minimal medical staff, often simply a medical technician or even an ordinary crewman with an additional qualification in emergency medicine. On larger vessels, as well as civilian transports, at least one doctor serves as a ship's medical officer.
Licensed medical officers are rated at a junior and senior level; a single certificate also exists for merchant certified nursing officers. Warranted medical personnel either serve as a medical specialist or technician.
Security Departments only exist onboard merchant vessel which carry a deflector shield system or offensive weaponry. In most cases, Security Officers are only assigned to armed merchant craft under the authority of the Department of the Starfleet (such as Shuttle Carriers or Military Transports). Ordinary merchant vessels, however, if properly outfitted, may also rate a Security Officer onboard.
Licensed Security Officers are rated in three levels. A Warrant Security Officer rating also exits, as well as a rate position of security specialist.
Science Departments are rare in the merchant service, and only are present only onboard civilian science craft.
Licensed science officers are rated in both a junior and senior grade. Warrant science ratings also exist, known as "Scientific Specialist" and "Scientist's Mate".
Civilian Departments are only present onboard transports carrying civilians or Starfleet vessels with crewmember families onboard.
With the exception of the Civilian Department Director, assisted by one or more Personnel officers, most civilian department employees are not considered regular merchant personnel and are hired by local advertisement to fill certain duties as members of service, administration or custodial staff. Onboard Starfleet vessels with younger children, a special classification is extended to educators and teachers hired to run civilian onboard schools.
Civilian department employees are not mandated by any form of rating or rank structure, and many perform their duties in civilian clothes. In some situations, however, the nature of the civilian employment will entail some type of uniform requirement, most often directly connected to the type of employment held by the civilian member.