((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.