Section 13.503 - Service requirements(a) Each applicant for a tankerman-engineer endorsement must present evidence of at least-(1) 90 days of service as an engineering officer on tankships or self-propelled tank vessels certified to carry DL or LG appropriate to the endorsement applied for;(2) 90 days of rating or cadet service in the engine department on tankships or self-propelled tank vessels certified to carry DL or LG appropriate to the endorsement applied for; or(3) A combination of the service in paragraphs (a) (1) and (2) of this section.(b) Each applicant already holding an MMD or MMC endorsed as tankerman-engineer for DL and seeking an endorsement for LG, or the converse, must prove at least half the service required by paragraph (a) of this section.CGD 79-116, 60 FR 17142, Apr. 4, 1995, as amended by CGD 79-116, 62 FR 25134, May 8, 1997; USCG-2006-24371, 74 FR 11260, Mar. 16, 2009; USCG-2004-17914, 78 FR 77997, Dec. 24, 2013