While on board a vessel inspected, or subject to inspection, under Chapter 33 of Title 46 United States Code, a crewmember (including an officer), pilot, or watchstander not a regular member of the crew:

(a) Shall not perform or attempt to perform any scheduled duties within four hours of consuming any alcohol;

(b) Shall not be intoxicated at any time;

(c) Shall not consume any intoxicant while on watch or duty; and

(d) May consume a legal non-prescription or prescription drug provided the drug does not cause the individual to be intoxicated.