((a)) ** .—** The Secretary may issue a merchant mariner credential, to members of the deck department in the following classes:

((1)) Able Seaman-Unlimited.

((2)) Able Seaman-Limited.

((3)) Able Seaman-Special.

((4)) Able Seaman-Offshore Supply Vessels.

((5)) Able Seaman-Sail.

((6)) Able Seaman-Fishing Industry.

((7)) Ordinary Seaman.

((b)) ** .—** The Secretary may classify the merchant mariner credential issued under subsection (a) based on—

((1)) the tonnage and means of propulsion of vessels;

((2)) the waters on which vessels are to be operated; or

((3)) other appropriate standards.

((c)) ** .—** To qualify for a credential under this section, an applicant shall provide satisfactory proof that the applicant—

((1)) is at least 18 years of age;

((2)) has the service required by the applicable section of this part;

((3)) is qualified professionally as demonstrated by an applicable examination or educational requirements;

((4)) is qualified as to sight, hearing, and physical condition to perform the seafarer’s duties; and

((5)) has satisfied any additional requirements established by the Secretary, including career patterns and service appropriate to the particular service, industry, or job functions the individual is engaged.