A crew is the group of people who operate a ship, aircraft, or vehicle. The crew sails the ship, flies the plane, drives the tank. Passengers ride. Crew work.

The ship determines what the crew must be. A cargo vessel needs navigators, engineers, and deckhands. A warship needs those plus weapons operators, sensor technicians, and damage control teams. A fishing boat needs a skipper and hands. The required roles come from what the ship is and what it does — the crew fills those roles with actual people.

Crew membership is formal. On a merchant ship, you sign the articles of agreement (46 U.S.C. § 10302) — a contract specifying the voyage, your position, your wages, and the rules. Signing on makes you crew. Signing off at voyage’s end dissolves your crew status. Being physically aboard without signing on does not make you crew — you are a passenger, a supernumerary, or a stowaway.

Every crew has a minimum size set by regulation, not by preference. The vessel’s Certificate of Inspection specifies how many people are needed to operate safely. Below minimum manning, the ship cannot legally sail. The number depends on the ship’s size, type, route, and level of automation.

A crew has a captain — the person with command authority. The captain is always a member of the crew, not an outside controller. Below the captain, roles are specialized: the chief officer runs deck operations, the chief engineer runs the machinery, watch officers take turns on the bridge. No one person can do everything. A crew works because each member does their part and the parts fit together.

The crew is temporary. It exists for a voyage, a deployment, a mission. The ship persists across crews. Different people sail the same ship year after year. The crew serves the ship, not the other way around.

The word comes from Old French creue (“growth, augmentation”), from Latin crescere (“to grow”). A crew is people added to make something work — reinforcements that bring an incomplete force to operational strength.