33 CFR 95.045 : Navigation And Navigable Waters (§ 1.01-1 To Parts 404-499) — (§ 1.01-1 To Parts 121-124) — Coast Guard, Department Of Homeland Security (§ 1.01-1 To Parts 121-124) — Vessel Operating Regulations (§ 95.001 To Subpart B) — Operating A Vessel While Under The Influence Of Alcohol Or A Dangerous Drug (§ 95.001 To § 95.050) — General operating rules for vessels inspected, or subject to inspection, under Chapter 33 of Title 46 United States Code.

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.