|Other names||Able-bodied seaman|
|Reports to||boatswain, chief mate|
|Duties||to be able at a moment's notice|
|Requirements||Able seaman's certificate|
|Watch (at sea)||Helmsman, Lookout (varies)|
|Watch (in port)||Varies (varies)|
An able seaman (AB) is a naval rating of the deck department of a merchant ship with more than two years' experience at sea and considered "well acquainted with his duty". An AB may work as a watchstander, a day worker, or a combination of these roles. Once a sufficient amount of sea time is acquired, then the AB can apply to take a series of courses/examinations to become certified as an officer.
At sea an AB watchstander's duties include standing watch as helmsman and lookout. A helmsman is required to maintain a steady course, properly execute all rudder orders and communicate utilizing navigational terms relating to heading and steering. A watchstander may be called upon to stand security-related watches, such as a gangway watch or anchor watch while the ship is not underway.
An AB day worker performs general maintenance, repair, sanitation and upkeep of material, equipment, and areas in the deck department. This can include maintenance of the ship's metal structures such as chipping, scraping, cleaning, priming, and painting. Areas frequently in need of such maintenance include the hull, decks, superstructure, cargo gear, and smoke stack. Day workers also frequently perform maintenance on lifeboats, rescue boats and liferafts, and emergency and damage control gear. For many vessels, being a dayworker is a position granted to senior AB's, since it generally allows more time for rest and relaxation.
An AB may be called on to use emergency, lifesaving, damage control, and safety equipment. Able seamen perform all operations connected with the launching of lifesaving equipment. An AB is expected to be able to operate deck machinery, such as the windlass or winches while mooring or unmooring, and to operate cargo gear.
Able seamen require advanced training, including lifeboatman certification.
The ship's boatswain, if carried, is typically a senior AB. The boatswain is in charge of the able seamen and ordinary seaman that comprise the unlicensed deck crew, and reports directly to the chief mate.
The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. (December 2010) (Learn how and when to remove this template message)
Time served in certain training programs and school ships may be substituted for the time of service listed above. Special certificates of service are available for able seaman, Great Lakes--18 months service; able seaman, any waters--12 months; able seaman, tugs and towboats--any waters; able seaman, bays and sounds--12 months, vessels 500 gross tons or less not carrying passengers; and able seaman, seagoing barges--12 months.
In 2004, studies indicate that a typical qualified Able Seaman (AB) sailing without an ITF contract might earn around $800 in total compensation; with an ITF contract total compensation is $1,300 per month.
Some notable able seamen from the merchant service include:
Some modern references claim that AB stands for able-bodied seaman as well as, or instead of, able seaman. Able seaman was originally entered using the abbreviation AB instead of the more obvious AS in ships' muster books or articles. Such an entry was likely to avoid confusion with ordinary seaman (OS). Later the abbreviation began to be written as A.B., leading to the folk-etymological able-bodied seaman. The "correct" term, able seaman, remains in use in legal documents, in seaman's papers, and aboard ship.