46 CFR § 13.403
Service requirements
April 15, 2021
(a) Each applicant already holding an MMD or MMC endorsed tankerman-assistant for DL and seeking one for LG, or the converse, must—
(1) Provide evidence of at least half the service required in §13.401(e)(2) of this subpart and successfully complete a professional examination for the topics identified in Table 1 to §13.121(e) of this part appropriate to the endorsement applied for; or
(2) Complete a course in DL or LG appropriate to the endorsement applied for as prescribed in §13.401(e)(1) of this subpart.
(b) [Reserved]
[USCG-2004-17914, 78 FR 77996, Dec. 24, 2013]