Military Sea Service: How USCG Credits It

Sea Service › Military Sea Service

By Captain Mike · 50 years at sea · former MITAGS faculty
Checked against the NMC's Crediting Military Sea Service guide (September 2022), the NMC Documenting Military Sea Service brochure (July 2026) and 46 CFR 10.232 · October 2026

The short answer

Sea service on Army, Navy, Air Force, Marine Corps, Coast Guard, NOAA and Public Health Service vessels can count toward a Merchant Mariner Credential (MMC), whether you served in uniform or as a civilian aboard.
The National Maritime Center (NMC) normally credits 60% of your total time assigned to a ship as sea service.
What it counts for depends on your rate or rank, your department, your watch qualifications, and the vessel's tonnage, horsepower and waters.
You need an official record of sea service. A DD-214 is not accepted, because it doesn't show the vessels, tonnage, horsepower or positions.

How much of your time counts

For applications received after March 24, 2019, the NMC normally calculates sea service at 60% of your total time onboard a ship. For example, 1,000 days assigned to a cutter would normally be credited as about 600 days. Some older applications were calculated at 70%; credentials already issued on that basis stay as they are. NMC guide

Tonnage still matters. Military vessels often aren't measured in gross tons, so the NMC accepts an estimate of full-load displacement × 0.57 to set the tonnage of your endorsement. Vessel Tonnage →

What your rate or rank may count as

These are the NMC's general guidelines. Enlisted evaluations are complex because duties vary so much; the NMC makes the final decision for each application. NMC brochure

Military service	May be treated as
Seaman Apprentice (SA) or Seaman (SN)	Ordinary Seafarer (formerly Ordinary Seaman) or deckhand
Fireman Apprentice (FA) or Fireman (FN)	Wiper
Deck petty officer, E-4 and above	Able Seafarer (AB) time
Engine petty officer, E-4 and above	QMED (Qualified Member of the Engine Department) time
Junior Officer of the Deck (JOOD)	AB time, day for day
Deck rating E-4 and above qualified as Deck Watch Officer (DWO)	Licensed mate time
Engine rating E-4 and above qualified as Engineering Watch Officer (EWO)	Licensed assistant engineer time
Officers serving as underway DWO or EWO	Licensed mate or engineer watchstanding, usable for an original or raise of grade

The full rating table is in the Coast Guard's Marine Safety Manual, Volume III, Chapter 2 (Figure 2-1).

Academy graduates. Graduates of the Coast Guard Academy or Naval Academy who qualified as an underway officer of a navigational or engineering watch may qualify for Third Mate or Third Assistant Engineer. 46 CFR 11.516
Army mariners. The Army has many watercraft certifications and licenses, and the Coast Guard has approved some of them for credit toward mariner credentials. Check the U.S. Army Transportation School's list of approved courses.

Small boats

Permanently assigned to a ship or cutter: you're credited for your time on the ship. You don't get extra credit for running its small boats. One exception: someone whose regular job doesn't earn sea time, such as a yeoman, who also qualified as a coxswain or boat crew, may document actual days underway on the boat.
Temporarily assigned (for example, a law enforcement detachment or special boat team aboard a ship): the ship time normally isn't credited, but properly documented days running the small boats can count day for day.
A small-boat day must be at least 4 hours in a 24-hour period. You can't add up hours to make a day, and extra hours beyond 4 earn nothing more.

Recency for officer endorsements

For an original deck or engineer officer endorsement, you need 90 days of service within the 7 years before you apply on uniformed-service vessels, or within the 3 years before you apply on other vessels, or a combination of both. NMC guide Recency explained →

The records you need

Your record must show each vessel's name or official number, your dates aboard, its horsepower, tonnage and area of operation, your rate or rank, and your position. 46 CFR 10.232

Service	What to get	Where
Coast Guard	Transcript of Sea Service (TOSS) for cutters. Small-boat time isn't on the TOSS; use an Abstract of Operations (AOPS) report.	USCG Pay and Personnel Center, or Direct Access
Navy	History of Assignments (HOA)	Navy Personnel Command (BUPERS / NPC)
Army	Sea-service information letter	Army Maritime Qualification Division, Joint Base Langley-Eustis, or request records with SF-180
All veterans	Military service records	National Archives, using Standard Form 180 (SF-180)

Watch qualification letters. Include proof of your Deck Watch Officer, Officer of the Deck or Engineering Watch qualifications (personnel qualification standards or designation letters). A missing qualification letter is one of the most common delays.
Shipboard letters signed by the commanding officer can show qualifications and duties, but normally can't replace your official sea-service record, and can only speak for that CO's own command.

Get your records before you separate. It's much easier to request a transcript and qualification letters while you're still serving than years later.

Common mistakes

Sending a DD-214 as proof of sea service.
Missing watch qualification letters when you want officer credit.
Asking for the "highest level possible." Apply for a specific endorsement. The NMC evaluates your service in the order you earned it, and you must meet each level before the next (for example, Third Mate before Second Mate).
Using engine time for a deck license, or deck time for an engine one.
Assuming military courses count. Most military training isn't Coast Guard-approved for mariner credentials. Check before you rely on one.
A CO vouching for service at another command. Each command can only document its own service.

THE CAPTAIN SAYS…

Your military time is worth real credit, but only if it's on paper the right way. Get your transcript and every watch qualification letter before you leave the service, then apply for the specific endorsement you want, not "whatever I qualify for."

Next step: Military to Mariner: GI Bill, MSC and next steps →

Ready to apply? Applications now go through Navita, the Coast Guard's online credentialing system. It changes how you apply, not what you need. Navita: what changed →

Official sources

For information only. Mariners Online is independent and not affiliated with the Coast Guard or any military service. The NMC decides how your service is credited; confirm with the NMC before you apply.