[1] Historically, in some navies and the merchant marine, a sailor with less experience was called a landsman.

[2] An OS is generally not required to stand watch, but must pass examinations on watchstanding skills such as performing lookout duty and being a helmsman.

During the apprenticeship, an OS performs a variety of duties concerned with the operation and upkeep of deck department areas and equipment.

The Code of Federal Regulations establishes in 46 CFR 12.05[4] four categories of able seaman for the United States Merchant Marine: Time served in certain training programs and school ships may be substituted for the time of service listed above.

For the United States Merchant Marine, the Code of Federal Regulations establishes in 46 CFR 12.05[4] examination requirements for the certification of able seamen, which includes: