46 C.F.R. § 15.817
Every person in the required complement of deck officers, including the Master, on seagoing vessels equipped with a GMDSS, except those vessels listed in § 15.105(f) and (g), must provide evidence of a valid STCW endorsement as GMDSS Radio Operator.
[USCG-2004-17914, 78 FR 78007, Dec. 24, 2013]