USCG Master’s License Requirements: Sea Service, Exam, and TWIC

To earn a U.S. Coast Guard Master’s License, you must be old enough for the credential you want, be a U.S. citizen, pass a physical and drug test, clear a character and background check, hold current first aid and CPR certificates, log the sea service tied to your target route and tonnage, pass either the Coast Guard exam or an approved course, and submit the application through a Regional Examination Center along with a valid TWIC and the required fees. The Coast Guard doesn’t issue one generic license: what you’ll actually need depends on where you plan to sail and how big a vessel you plan to command. The National Maritime Center (NMC), a Coast Guard headquarters unit, evaluates every application and issues the credential.¹

Pick Your Route and Tonnage First

Master endorsements sit on a grid of operating routes and vessel tonnage limits, and every requirement below scales with that combination. Figure out which square you’re aiming for before you gather anything else.

The four route tiers are:

Oceans: unlimited geographic range.
Near Coastal: waters up to 200 miles offshore.
Great Lakes: the five Great Lakes and connecting waterways.
Inland: rivers, bays, sounds, and other internal U.S. waters.

Common tonnage tiers are under 100 gross register tons (GRT), under 200 GRT, under 500 GRT, under 1,600 GRT, and unlimited. A charter fishing captain typically needs a Master 100 GRT Near Coastal; running a large commercial ship on international routes calls for a Master Unlimited Oceans. Sea service demands and exam difficulty rise as the route widens and the tonnage climbs.

Baseline Eligibility

Federal regulations set requirements every Master applicant must meet, regardless of route or tonnage.²

Age

The default minimum age is 21. Some lower-tonnage credentials are available sooner: Master of near-coastal, Great Lakes, or inland vessels between 25 and 200 GRT is open at 19, and limited Master credentials for vessels under 100 GRT are open at 18.²

Citizenship

You must be a U.S. citizen. The only exception for officer endorsements applies to operators of uninspected passenger vessels that aren’t documented under U.S. law.²

Character and Background Check

The Coast Guard investigates your habits and character before issuing a credential. If the review turns up information suggesting you can’t be trusted with the responsibilities of the endorsement, or that your application was false or incomplete, the Coast Guard can declare the credential void and require you to return it.² Not disclosing a criminal conviction is one of the fastest ways to lose a credential you already hold.

Medical Exam and Drug Test

You need a physical exam documented on Form CG-719K, where a licensed physician evaluates your vision, hearing, and general fitness for sea service, plus a drug test on Form CG-719P showing a negative result from an accredited lab. If you don’t meet the medical standards, the Coast Guard may grant a waiver when the circumstances justify it. There is no separate waiver application; the Coast Guard decides during its review of your CG-719K. A waiver typically shortens the medical certificate’s validity to one or two years and comes with a waiver letter you have to carry aboard whenever you sail.³

First Aid and CPR

You’ll need certificates for both a first aid course and a CPR course. The Coast Guard accepts first aid training from the American Red Cross Standard First Aid program or any Coast Guard-approved course. For CPR, certificates from the American Red Cross and the American Heart Association both qualify.⁴

Sea Service

Sea service is where most of the time investment lives, and it’s where most applications stall. The Coast Guard sets different minimums for each credential, and the math has to be right before your file moves forward.

Minimums by Credential

For a Master of ocean self-propelled vessels under 200 GRT, you need three years of total service on ocean or near-coastal waters, with two of those years served as Master, Mate, or equivalent while holding the appropriate endorsement. Great Lakes and inland service can substitute for up to 18 months.⁵

For a Master of near-coastal vessels under 200 GRT, the total drops to two years, with one year as Master, Mate, or equivalent. Great Lakes and inland service can substitute for up to one year.⁶

For a Master of Great Lakes and inland vessels under 200 GRT, you need one year of total service, with six months as Master, Mate, or equivalent. To get Great Lakes authority specifically, at least three months of that service must have been on Great Lakes waters; without it, your endorsement is limited to inland waters.

If you don’t have enough time on the largest vessels you’d like to command, the Coast Guard doesn’t necessarily deny the application. Instead, you may receive a tonnage limitation on your credential based on the sizes of the vessels you actually served on.⁷ Most mariners step up in tonnage over the course of a career rather than reaching the top tier in one application.

How a Day Is Counted

A standard day of sea service is eight hours of watchstanding or day-working, not counting overtime. On vessels under 100 GRT, four hours or more earns a full day; less than four earns nothing. On vessels authorized to operate a two-watch system, a 12-hour working day counts as one and a half days.⁸

Recency

Old sea time alone won’t do it. You need at least three months of qualifying service on appropriately sized vessels within the seven years before you apply.⁹

Documenting Your Time

The NMC is exacting about proof. Every service letter or record must include the vessel’s name and official number, its gross tonnage and propulsion type, your position aboard, the specific dates of service, and the routes you sailed.¹⁰

Commercial service is typically documented in a letter on company letterhead signed by the vessel’s owner, operator, Master, or Chief Engineer. On vessels under 200 GRT, owners may attest to their own time if they provide proof of ownership; if you served on someone else’s vessel under 200 GRT, you’ll need a letter from a credentialed mariner or the vessel’s owner.¹⁰ The service itself is recorded on Form CG-719S.¹¹

Exam or Approved Course

You have two ways to prove professional competence. The first is sitting for the Coast Guard national exam at a Regional Examination Center, which covers navigation, rules of the road, and deck general safety, with scope and difficulty rising at higher tonnage levels.¹²

The second is completing a Coast Guard-approved course at a certified maritime school. When you pass the school’s final exam, the course certificate substitutes for the government test. That certificate is valid for one year, so submit your application promptly after completing the course.¹³ Certificates that don’t substitute for an exam have a five-year validity window instead. Either way, all certificates go into your application package. Regional Examination Centers pre-screen applications for completeness and administer the exam for those taking the government test route.¹⁴

TWIC and FCC Radio Permit

A valid Transportation Worker Identification Credential is required before you submit your application. TSA administers the TWIC through a fingerprint-based background check. A new applicant card costs $124 and is valid for five years.¹⁵

If you’ll be operating a vessel with HF radio, traveling in foreign waters with VHF, or commanding a vessel 20 meters or longer where a marine radio is legally required, you also need a Restricted Radiotelephone Operator Permit from the FCC. The permit is lifetime, with no test but a processing fee.¹⁶

Forms, Fees, and Submission

The main application is Form CG-719B, which collects your personal and professional history.¹¹ Filed alongside it:

CG-719K, the physical examination form completed by a licensed physician.
CG-719P, the drug test verification form showing a negative result.
CG-719S, the sea service record for every vessel and period of service claimed.

All forms are on the NMC’s website. Fees are paid through Pay.gov.¹⁷ What you’ll pay depends on the credential level:

Lower-level original (under 1,600 GRT): $100 evaluation, $95 examination, $45 issuance, for $240 total.
Upper-level original (unlimited tonnage): $100 evaluation, $110 examination, $45 issuance, for $255 total.
Renewal: $50 evaluation, $45 examination, $45 issuance, for $140 total.

Those are Coast Guard fees only. Budget separately for the TWIC ($124), a DOT-compliant drug test (typically $45 to $150 depending on the facility), and any approved training course tuition, which varies by school and credential level.

Compile the forms, training certificates, sea service documentation, and TWIC receipt into a single PDF and submit it electronically through a Regional Examination Center. The NMC then begins evaluation and security review. Processing times vary with backlogs and how clean your paperwork is. You can track your file through the NMC’s online tracking tool.¹⁸ Once approved, the credential is mailed to your address.

Validity and Renewal

A Merchant Mariner Credential is valid for five years from issuance. You cannot serve under an expired credential.¹⁹

To renew, you need 360 days of sea service during the five years before your application date.²⁰ If you’re short, you can instead pass a comprehensive open-book exercise, complete an approved refresher course, or show at least three years of employment during the past five in a position closely related to vessel operations, construction, or repair.²¹

Under a temporary policy effective as of 2024, the Coast Guard extended the administrative grace period for renewal from one year to six years past expiration. You can renew an expired credential up to six years after it lapsed without starting from scratch, though you still can’t sail during that window. The policy stays in effect indefinitely until the Coast Guard issues further guidance.²²

When STCW Also Applies

If you’ll sail internationally, the Standards of Training, Certification, and Watchkeeping (STCW) convention adds a separate layer of training and certification. STCW does not apply to every Master. You’re outside its scope if your vessel operates exclusively on the Great Lakes or U.S. inland waters, if you command a vessel under 200 GRT on domestic or near-coastal routes, or if you operate a small passenger vessel subject to Subchapter T or K regulations beyond the boundary line. Fishing vessels and barges are also exempt.²³ If STCW does apply, expect approved courses in advanced shiphandling, stability, meteorology, leadership, search and rescue, and medical care management, along with current basic training and advanced firefighting certificates.²⁴

1
United States Coast Guard. About the National Maritime Center
2
eCFR. 46 CFR 11.201 – General Requirements for National and STCW Officer Endorsements
3
National Maritime Center. Frequently Asked Questions – Medical Certificates
4
eCFR. 46 CFR 28.210 – First Aid Equipment and Training
5
eCFR. 46 CFR 11.424 – Requirements for Master of Ocean Self-Propelled Vessels of Less Than 200 GRT
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eCFR. 46 CFR 11.426 – Requirements for Master of Near-Coastal Self-Propelled Vessels of Less Than 200 GRT
7
United States Coast Guard. National Master of Self-Propelled Vessels of Unlimited Tonnage Checklist
8
eCFR. 46 CFR 10.107 – Definitions in Subchapter B
9
National Maritime Center. Recency Credit
10
eCFR. 46 CFR 10.232 – Sea Service
11
United States Coast Guard. Application for Merchant Mariner Credential CG-719B
12
United States Coast Guard. Q450 Navigation General – Rules of the Road
13
United States Coast Guard National Maritime Center. Frequently Asked Questions – Courses
14
United States Coast Guard. National Maritime Center – Regional Examination Centers
15
Transportation Security Administration. TWIC
16
United States Coast Guard Navigation Center. FCC Radio Licenses
17
United States Coast Guard. National Maritime Center Fees FAQ
18
National Maritime Center. National Maritime Center Home Page
19
eCFR. 46 CFR 10.205 – Validity of a Merchant Mariner Credential
20
United States Coast Guard. National Renewal Checklist
21
eCFR. 46 CFR 10.227 – Requirements for Renewal
22
United States Coast Guard. Temporary Extension of Administrative Grace Period for Credentialing Transactions
23
eCFR. 46 CFR 11.301 – Requirements for STCW Officer Endorsements
24
United States Coast Guard National Maritime Center. Checklist for STCW II/2 – Master 3000 GT or More Management Level