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Providing Credentials to Mariners
The Code of Federal Regulation (CFR) mandates that all mariners who want to sail in US waters are required to have a Merchant Mariner Credential (MMC). When applying for your MMC, documentation must be provided that clearly shows your sea time.
The links below are provided to assist you in calculating your sea time.
Start with our checklist to see the Sea Service requirements specific to the position for which you are applying before doing the calculations.
- Checklist
- Sea Service Calculator (ZIP file)
- Types of Sea Service
- Small Vessel Sea Service - Form CG-719S
- SAMPLE General Sea Service Letter
- SAMPLE Tankerman PIC Sea Service and Transfer Letter
- SAMPLE Tankerman PIC (Barge) Sea Service/Employment and Transfer Letter
According to the CFR’s you should have received a certificate of discharge documenting your sea service. You will need to provide a copy of this document with your application. International Mariners or military seamen will have a different type of sea service documentation - see type of sea service for further information.
(a) Each master or individual in charge of a vessel shall, for each Merchant Mariner being discharged from the vessel, prepare a certificate of discharge and two copies; whether by writing or typing them on the prescribed form with permanent ink or generating them from computer in the prescribed format; and shall sign them with permanent ink (Section 14.307, para. a).
In order to count your days of seagoing service you must understand that a “day” is defined in the regulations as “eight hours of WatchStanding or day-working not to include overtime.” For vessels under 100 GRT, however, you may receive a day’s credit for less than eight hours, but in no case will the acceptable period be less than four hours.
12 Hour Work Day
If you work on a vessel where a 12-hour day is authorized and practiced (crew boats, supply boats, towboats, and some commercial fishing boats), you can claim one-and-a-half days for each 12 hour day worked. A 20 day hitch is thus transformed into 30 days of sea time. The 24 months (720 days) that you need to qualify for a license can be reduced to 480 “12-hour” days – if you have served on vessels that are authorized to work a two watch system. To claim this time, your documentation of service must specifically state that you worked 12 hours per day.
Time Served on a Vessel
When reading the requirements, keep in mind that “sea service” means time on the vessel – not time of employment. You may have been employed by a towboat company (or several) over a period of 4 years and two months, for example, but the Coast Guard will only credit you with the time you spent on the boat.
NMC Customer Service Center (CSC): 1-888-IASKNMC (1-888-427-5662) email (IASKNMC@uscg.mil)
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