Members of the U.S. Merchant Marine are persons employed on board merchant vessels of the United States. They are civilians and are hired either directly by a steamship company or through a marine labor union operating merchant vessels. All persons employed aboard United States merchant vessels of 100 gross tons or more are required to have a valid U.S. Merchant Mariner's Document (MMD), also known as a Z-card or seaman's papers, from the U.S. Coast Guard, which sets the requirements for the licensing and documentation of mariners.
Each mariner credential has specific requirements as to age, citizenship, physical condition, character, qualifying sea service, assessments, and specialized training. These requirements are found in the Code of Federal Regulations, Title 46, Parts 10, 12, 13, and 15, and those pertaining to the Able Seaman are summarized below. The regulations were designed to closely conform to the provisions of the International Convention on Standards, Training, Certification and Watchkeeping for Seafarers (STCW), 1978 . The 1995 amendments to STCW introduced some changes in how U.S. domestic licensing and documentation requirements are applied to meet the STCW Code.
There are several ratings available and more than one may be combined on one MMD. The following is a summary of MMD ratings:
A MMD without qualified ratings means an entry level MMD that allows you to work as an ordinary seaman in the deck department, a wiper in the engineering department or as a member of the Steward's department. An entry level MMD does not require prior maritime experience. A physical examination is not required, but an applicant must pass a chemical test for dangerous drugs.
A MMD with a qualified rating in the deck department may be endorsed as Able Seaman (AB) or Lifeboatman (LB).
There are seven Able Seaman (AB) ratings available for the MMD: Able Seaman-Unlimited, Able Seaman-Limited, Able Seaman-Special, Able Seaman-Offshore Supply Vessels, Able Seaman-Fishing Industry, Able Seaman-Sail, Able Seaman-Mobile Offshore Units (MOU).