On smaller vessels there is less need for complicated hierarchies. Smaller boats operating only by day or on limited runs may simply have a captain with everyone else being a deckhand. Interactions will be direct, rehearsed, and simple. Larger vessels with more complex operations will require further definition of responsibilities with separate departments and watches assigned within those departments. The titles and responsibilities of these departments, watches, officers, and sailors will differ depending on the type of vessel, the task the vessel is undertaking, and the culture of the industry that the vessel and crew are a part of.
Watch leaders are, generally speaking, specialists in their trade. While the Captain is the ultimate authority onboard ship, as well as the primary watch leader for the navigational watches, he must also rely on specialists outside of his primary education for operation of complex machinery and day-to-day operations such as the feeding of the crew. Beneath the captain are the mates, the line officers of the vessel. Each act as an officer in charge of a navigational watch (OICNW) and will lead a watch of their own containing qualified members of the deck department. These deckhands, or ratings forming part of the navigational watches (RFPNW), will be responsible for assisting in the operation of the vessel (such as steering, or helming), performing lookout duties from the bridge, and making reports of navigational value. The mates will interact directly with the deck crew to assign tasks or oversee more complex operations. Simpler and routine operations are generally led by watch leaders within the deck departments.
A deck department watch leader may be a senior deckhand such as a boatswain, deck boss, or some other title. They will be responsible for directing the crew during ship operations such as anchoring or or leading work parties for general maintenance. While theoretically the mate may issue commands to any deckhand at any time it presents less confusion for the deckhand, who may already be assigned a separate task, for the mate or captain to issue commands through the senior deckhand.
The Chief Engineer is in charge of the engineering department and is directly aided by the assistant engineers. Each of these act as an officer in charge of an engineering watch (OICEW) and interact directly with the qualified members of the engine department (QMED). Each watch operates for periods of time throughout the day just like the deck department, each one in turn overseeing the operation of the ship’s machinery, electrical production and distribution, systems such as refrigeration, as well as deck equipment.
The engineering crew beneath the assistants will be comprised of oilers, the more experienced QMEDs, and wipers, the less experienced QMEDs. Larger vessels will also have specialties such as machinists, pump men, fire men, electricians, and junior engineers. Again, theoretically the Chief Engineer, an assistant, a mate, or a captain may directly issue commands to a wiper, but that wiper probably has a number of mundane tasks assigned which may lead to disruption and confusion when the overall chain of command is skipped.
The final primary department onboard ship is the realm of the Chief Steward, or “Chief Stew,” and must oversee the operation of the hotel and accommodation aspects of the vessel. On a workboat this typically means food, but on a cruise liner or private yacht this may include rooms and other public spaces. Watches will extend overnight for meals provided to the various night watches, food prep for the following day, as well as laundry services.
Some specialists are day laborers holding no place in the watch structure. These people sleep at night and perform their work during the day (unless the situation demands otherwise) and are known as idlers. They may be dedicated carpenters, electricians, plumbers, and so forth, and are typically found on larger crews. On some ships, the captain is actually an idler, able to come and go as necessary, each watch being led by one of the mates. Most medium and smaller sized vessels have no room for idlers.