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Sea Service for your USCG License Defined

Every day that you are serving on a vessel in an assigned position where you worked for more than 4 hours is a sea day. A “day,” as defined by 46 CFR §10.107 is dependent on the tonnage of the vessel. For vessels over 100 GRT a “day” is 8 hours of watch-standing or day-working, not to include overtime. For vessels under 100 GRT you must be underway for at least 4 hrs in a day for it to count as a “day”.





No matter if you are sailing a 1000 ft tanker, 209 ft research boat or your 14 ft sailboat a sea day is a sea day. For the person on the tanker and the research boat it means the day they report and the day they depart as long as they work 8 hours they receive a “day” of sea day credit. This also means that you get a “day” of sea day credit if you are taking your small sailboat out for over 4 hours.


There are a few very special vessels which are listed in 46 U.S.C. 8104 and 46 CFR 15.705, who are authorized to operate a two-watch system, a 12-hour working day may be creditable as 1.5 “days” of service only on those vessels.


The types of vessels listed in 46 U.S.C. 8104 and 46 CFR 15.705


Towing vessels and Barges who are engaged on a voyage of less than 600 miles and the licensed individuals and crewmembers are divided, when at sea, into at least 2 watches can receive time and a half credit for every sea day they work 12 hours.


Offshore Supply Vessels that are at least 6,000 gross tons who are engaged on a voyage of less than 600 miles, and the licensed individuals and crewmembers are divided, when at sea, into at least 2 watches can receive time and a half credit for every sea day they work 12 hours.


Fish Processing Vessels who entered into service before January 1, 1988, and are more than 1,600 gross tons and the licensed individuals and crewmembers are divided, when at sea, into at least 2 watches can receive time and a half credit for every sea day they work 12 hours.


Fish Processing Vessels who entered into service after December 31, 1987, and has more than 16 individuals on board primarily employed in the preparation of fish or fish products and the licensed individuals and crewmembers are divided, when at sea, into at least 2 watches the licensed individuals and crew members can receive time and a half credit for every sea day they work 12 hours.


If you are a cadet sailing on a training ship furnished by the Maritime Administration under 46 CFR 310.4, a day may be creditable as 1.5 days of service.


There are many examples of companies and government agencies (especially the NOAA Fleet) issuing sea service letters with 12 hr days when it is not authorized. The USCG National Maritime Center will typically only give the mariner one sea day for each day worked no matter what the letter says. We encourage mariners to be realistic and understand the rules that they are working with. We would never want a mariner to have obtained a license they were not qualified for due to illegal paperwork from their employers and mistakes by the evaluators at the USCG National Maritime Center.


If you need any help or have more questions about sea service use the “Ask us anything maritime” above!


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