46 CFR §15.1109

Except those serving on vessels listed in § 15.105(f) and (g), each Master of a vessel that operates beyond the boundary line, as described in part 7 of this chapter, must ensure observance of the principles concerning watchkeeping set out in Regulation VIII/2 of the STCW Convention and section A-VIII/2 of the STCW Code (both incorporated by reference, see § 15.103).