46 C.F.R. § 15.850

(a) The requirements for the maintenance of a proper lookout are specified in Rule 5 of the International Regulations for Preventing Collisions at Sea, 1972 (33 U.S.C. 1602(c)), and Rule 5 of the Inland Navigational Rules Act of 1980 (33 CFR part 83). Lookout is a function to be performed by a member of a navigational watch.

(b) On vessels subject to STCW, the individual meeting the requirement of this section must also hold at least an STCW deck endorsement as Rating Forming Part of a Navigational Watch (RFPNW), except as noted in § 15.105(g) for vessels on domestic near-coastal voyages.