46 U.S.C. § 8702 — Certain crew requirements

a vessel operating only on rivers and lakes (except the Great Lakes);

a barge^* (except a seagoing barge or a barge to which chapter 37 of this title applies);

a fishing, fish tender, or whaling vessel (except a fish tender vessel engaged in the Aleutian trade) or a yacht;

a sailing school vessel with respect to sailing school instructors and sailing school students;

an oceanographic research vessel with respect to scientific personnel;

a fish processing vessel entered into service before January 1, 1988, and not more than 1,600 gross tons as measured under section 14502 of this title, or an alternate tonnage measured under section 14302 of this title as prescribed by the Secretary under section 14104 of this title or entered into service after December 31, 1987, and having not more than 16 individuals on board primarily employed in the preparation of fish or fish products; and

a fish processing vessel (except a vessel to which clause (6) of this subsection applies) with respect to individuals on board primarily employed in the preparation of fish or fish products or in a support position not related to navigation.

75 percent of the crew in each department on board is able to understand any order spoken by the officers, and

65 percent of the deck crew (excluding licensed individuals) have merchant mariners’ documents endorsed for a rating of at least able seaman, except that this percentage may be reduced to 50 percent—