46 CFR § 11.211 - Creditable service and equivalents for national and STCW officer endorsements.
(c) Service on mobile offshore drilling units.
(1) MODU service is creditable for raise of grade of an officer endorsement. Evidence of 1 year of service on MODUs as mate or equivalent while holding an officer endorsement or license as third mate, or as engineering officer of the watch or equivalent while holding an officer endorsement or license as third assistant engineer, is acceptable for a raise of grade to second mate or second assistant engineer, respectively. However, any subsequent raises of grade of unlimited, non-restricted officer licenses or endorsements must include a minimum of 6 months of service on conventional vessels.
(2) Service on MODUs maintaining station by means of dynamic positioning, may be credited as service on conventional vessels for any raise of grade; however, time more than 8 hours each day will not be credited.
(3) A day of creditable MODU service must be a minimum of 4 hours, and no additional credit will be granted for periods of more than 8 hours.
(4) Creditable MODU service excludes time spent ashore due to crew rotation.
(d) Service on Articulated Tug Barges (ATBs) and Integrated Tug Barges (ITBs). Service on ATB or Dual Mode ITB units is creditable for an original deck officer endorsement or raise of grade of any deck officer endorsement. Service on an ATB or Dual Mode ITB with an aggregate tonnage of 1,600 GRT/3,000 GT or more is creditable on a two-for-one basis (2 days experience equals 1 day of creditable service) for up to 50 percent of the total service on vessels of 1,600 GRT/3,000 GT or more required for an unlimited officer endorsement. The remaining required service on vessels of more than 1,600 GRT/3,000 GT must be obtained on conventional vessels or Push Mode ITBs.
(e) Service on towing vessels. Service as master or mate (pilot) on towing vessels, when the aggregate tonnage of the tug and barges is 1,600 GRT/3,000 GT or more, is creditable, using the aggregate tonnage, on a two-for-one basis (2 days experience equals 1 day of creditable service) for up to 50 percent of the total service on vessels of 1,600 GRT/3,000 GT or more required for an unlimited officer endorsement. The remaining required service on vessels of more than 1,600 GRT/3,000 GT must be obtained on conventional vessels. This service must be documented as specified in § 10.232(a) of this subchapter.
(f) Individuals obtaining sea service as part of an approved training curriculum pursuant to either § 11.407(a)(2) or § 11.516(a)(3) of this part must do so in the capacity of cadet (deck) or cadet (engine), as appropriate, notwithstanding any other rating endorsements the individual may hold or any other capacity in which the individual may have served.
(g) Other experience. Other experience in a marine-related area, other than at sea, or sea service performed on unique vessels, will be evaluated by the Coast Guard for a determination of equivalence to traditional service.
(h) Tonnage. When determining sea service credit for officer endorsement applicants under subpart D of this part, the tonnage of a vessel solely admeasured using the Convention measurement scheme under 46 U.S.C. Chapter 143 will be credited as Gross Register Tonnage. This paragraph does not apply to those vessels measured under the optional regulatory measurement provisions of 46 U.S.C. 14305.