Your Go-to Merchant Mariner Credential Guide to Set Sailing

Explore how MMC can elevate your maritime career. Discover roles, ratings, and more.

6 mins read・Oct 31, 2023
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In the maritime world, there's two things that tell the rest of the community that you are a professional: your Merchant Mariner Credential (MMC) and how well you do your job. It’s almost impossible to move up in your career if they don’t match. An MMC ain't no fancy diploma; it's your ticket to a life less ordinary.

Forget the suits and ties; we're talking about a different kind of professional here. If chipping rust, turning a wrench and then steering a ship before breakfast sounds like fun to you, a MMC is what you need to crack the door wide open. We’re going to dive deep into what Merchant Mariner Credentials (MMCs) are all about, no fluff, no frills.

Importance of Merchant Mariner Credentials (MMC)

Merchant mariners play a crucial role in supporting the U.S. maritime commerce industry, contributing significantly to an estimated $5.4 trillion in annual economic activity. Beyond commerce, they also play a vital role in national defense by providing essential support in times of emergencies or war.

These mariners are civilians who fulfil various roles typically on privately-owned U.S. registered merchant, towing, and passenger vessels. There are a few positions for mariners on government owned vessels as well. Their positions range from deck officers and engineers to stewards responsible for services like making sure everyone is fed aboard the vessel.

Types of Ratings and Officer Positions on the USCG Merchant Mariner Credentials

In the professional maritime sector, the USCG Merchant Mariner Credential (MMC) is the key that unlocks your career progression into various jobs and duties. 

Mariner credentialing infographic.

There are many different roles, and we'll look at some of the common ones:

Deck Officers:

  • Master: Holds the highest authority on the ship and is also called “Captain”.
  • Mate: These officers serve various roles on the ship and may include the Chief Mate, Second Mate, Third Mate, and others, each with specific duties. The Chief Mate often takes on the role of the second-in-command, assisting the captain.

Engine Officers:

  • Chief Engineer: The leader responsible for overseeing the ship's mechanical systems.
  • First Assistant Engineer: This officer supports the Chief Engineer in maintaining and operating the ship's machinery.

Qualified Members of the Engine Department:

These are individuals who work in various roles within the engine room, contributing to the vessel's mechanical operations.

Able Seaman:

A vital part of the deck crew, involved in the day-to-day operations and maintenance of the vessel.


Tankerman PIC (DL or LG): Specialized mariners handling bulk liquids or gases, such as those on oil tankers or liquefied natural gas carriers.

Entry Level:

  • Ordinary Seaman: They support the deck crew and undertake various tasks on the ship including those responsible for steering the ship safely.
  • Wiper: They support the ship’s engineers and are typically responsible for keeping the engine spaces and machinery of a ship clean.

Eligibility Requirements for USCG Licenses and Endorsements

To obtain various licenses and endorsements from the United States Coast Guard (USCG), mariners must meet specific eligibility criteria, which vary depending on the type of license or endorsement sought. Below is an overview of the common eligibility requirements, qualifications, and examples for USCG licenses and endorsements.

  1. U.S. Citizenship: Applicants for USCG Captain or Engineer licenses must be U.S. citizens. You can obtain your OUPV as a non-citizen but it is only valid on vessels that are not documented under the laws of the United States. For all USCG Ratings including QMED, Able Seaman and Entry Level MMCs you must be a citizen of the United States; a person who is lawfully admitted to the United States for permanent residence or a foreign national who is enrolled in the United States Merchant Marine Academy (USMMA).
  2. Age Requirements: The minimum age for applicants varies by endorsement type, ranging from 16 to 21 years. For example, candidates applying for Master of Self-propelled vessels of 500 GRT upon Near Coastal waters must be at least 21 years of age while a Master of Self-propelled vessels of 100 GRT upon Inland Waters (100 ton Captains license) only needs to be 19 years old. However, for an Entry Level MMC which includes Ordinary Seaman, Wiper and Food Handler you only need to be 16 years old.
  3. Sea Service, Route and Tonnage Requirements: Eligibility for each USCG endorsement hinges on a calculation of your accumulated sea service days which are then compared to the specific requirements based on the endorsement you are seeking. The sea service requirements typically include a total number, number of days on specific water types, the size of the vessel as well as the amount within the past three years. Mariners may need to provide proof of service in the deck or engine department, depending on their role.
  • For example - To qualify as a Master Of Self-Propelled Vessels Of Less Than 100 GRT Upon Near Coastal Waters you must accrue 720 days in the deck department of which 360 may be on Great Lakes or Inland waters. The rest of your sea days need to be on Near Coastal waters or the Ocean. You will also need either 180 days on vessels of at least 51 GRT or 360 days of service on vessels that are 34 GRT or above. On top of that, you need to have 90 days of sea service in the last three years. You need to meet all of the eligibility criteria for sea service days to qualify for a 100 ton Near Coastal Captain's License.
  • An Able Seaman - Limited must have 360 days deck service on the navigable waters of the U. S. which includes all your time on the Ocean, Near Coastal, Inland or Great Lakes waters on any size vessel.
  • A Designated Duty Engineer (DDE) of Motor Propelled Vessels of Less Than 1000 HP / 750kW on Vessels of Less Than 500 Gross Register Tons (GRT) or in normal boat talk a DDE 1000hp for Motor Vessels, needs to have 360 days of service working in the engine room on vessels that actually have an engine room. 180 of those sea service days must be as a Qualified Member Of The Engine Department (QMED) or equivalent position as documented on your sea service letter by clearly stating QMED or “Equivalent position to QMED'' for your position served on the Sea Service Letter you get from your company.
  1. Training and Certification: Depending on the endorsement you are adding to your MMC, your path to proficiency may require you to complete a specialized training accredited by the USCG. The USCG endorsement checklists will guide you on exactly what you need. These can include:
  • CPR / First Aid (CPR/ FA)
  • Basic Fire Fighting (F/F)
  • Advanced Fire Fighting (Adv F/F)

Additionally, there are STCW endorsements which are issued from the USCG that require specific training. STCW endorsements are required for a very limited number of ships in the U.S., mainly those operated by unions that provide training to their members. A typical benefit of union membership is providing you with all of your training at no cost. We recommend that you only take STCW training if it is required by your employer and someone else is paying for it, typically your union. These can include, not limited to:

  • STCW Basic Training (STCW BT) which includes: Basic Fire Fighting (STCW F/F), Personal Safety and Social Responsibility (PSSR), STCW Personal Survival Techniques (PST) and STCW CPR / First Aid (STCW CPR/ FA)
  • STCW Rating Forming Part of a Navigational Watch (RFPNW)
  • STCW Rating Forming Part of a Engineering Watch (RFPEW)
  1. Approved Course Programs: The majority of courses that you take related to USCG licensing replace the need to take the tests at a USCG Regional Exam Center. The course will take the time to help you learn the required knowledge, verbiage and standards so you can pass the USCG exam. Courses can range from a week to a few years depending on the course you select and what endorsements are included. You can take courses to get any Captain or Mate licenses up to 200 GRT, Apprentice Mate of Towing, increase your scope from Near Coastal Waters to Oceans for a 500 or 1600 GRT Mates license or even get your DDE 4000hp. These can include, not limited to:
  • 100 ton Captains License 
  • OUPV / Six Pack
  • Able Seaman
  • DDE 1000hp
  • QMED

You can refer to the approved courses list given by USCG which lists all of the courses you can take to substitute for the examinations.

USCG licenses and endorsements have diverse eligibility criteria, from citizenship and age requirements to sea service and training mandates. This is a confusing web of rules and regulations that we never recommend anyone navigate alone.

We recommend finding a mentor that will help you understand the USCG License requirements as well as using USCG licensing software tools like MM-SEAS. If you don’t have a mentor, our MM-SEAS team of USCG licensing specialists are trained industry professionals who can help you set up a plan to achieve your USCG licensing dreams for MM-SEAS PRO Members.

USCG licensing eligibility criteria.

How to Get and Apply for a USCG Medical Certificate

  1. Complete a CG-719K Application for Medical Certificate or CG-719K/E Application for Medical Certificate ONLY for Entry Level Ratings (Ordinary Seaman, Wiper and Food handler).
  2. Submit your medical forms and supporting documentation for your Medical Certificate as one pdf to the USCG Medical team via email, ensuring accuracy to avoid delays or rejection. Email directly to and we recommend obtaining your USCG Medical Certificate before you start your USCG licensing journey or take any courses.

How to Get and Apply for a Merchant Mariner Credential (MMC)

  1. Identify the specific MMC Officer and/or Ratings you aim to obtain by understanding the corresponding USCG MMC license requirements. Seek expert guidance from specialized USCG application tools like MM-SEAS software for detailed insights, bearing in mind that each officer and/or rating has distinct eligibility requirements.
  2. Undergo Drug Testing using a CG-719P Periodic Drug Testing Form or you can choose from alternative options listed on Page 2 of the CG-719P form.
  3. Apply for a Transportation Worker’s Identification Credential (TWIC) and ensure your occupation is listed as "Merchant Mariner." If you are renewing or upgrading you may not need a TWIC.
  4. Complete a CG-719B Application for Merchant Mariner Credential.
  5. If applicable based on the specific requirements, Complete a CG-719C Conviction Statement.
  6. Pay user fees at Print the payment receipt for submission with your application.
  7. If applicable, complete CG-719S Sea Service forms, provide other documented sea service in the correct format and any supporting documentation as needed. This may also include any approved course(s) which may satisfy a portion of the service requirements.
  8. Provide relevant Training and Course Certificate(s) and/or Assessment(s), if applicable.
  9. Submit all forms, photocopies, and supporting documentation for your MMC as one pdf to a Regional Exam Center (REC) via email, ensuring accuracy to avoid delays or rejection.

MM-SEAS USCG licensing software is built to walk you through each of these steps to get your USCG license so that your course is clear.

Merchant Mariner Credential Upgrades or Advancements

Upgrades are called either a Raise of Grade or an Increase in Scope in the context of a Merchant Mariner Credential (MMC) but we just call them all upgrades. Any time you elevate the level of authority and responsibility associated with the credential it’s an upgrade. This process typically involves upgrading to a higher officer or rating position which is reflected by your increased proficiency, experience, and capabilities within the maritime field.

Just like the initial MMC application, every upgrade or raise of grade comes with specific requirements. Sometimes it requires a new course, sometimes lots of training and other times it’s just more sea service experience. For example, transitioning from Master 100 GRT Inland to Near Coastal has distinct criteria, while broadening the scope from Mate 200 GRT to Master 200 GRT Near Coastal involves a different set of requirements.

USCG MMC License Renewal

Getting your initial USCG Merchant Mariner Credential is a great achievement but keeping it valid so you can always work on it is the mark of a true maritime career professional. Your USCG license needs to be renewed every five years and you need absolutely zero sea time to renew it.

Depending on which Officer and/or Ratings you hold in addition to any STCW endorsements as well as how many creditable sea days towards those specific renewals you have accumulated in the last 5 years will dictate the possible exams and training you need to renew.

Your renewal can be as simple as just turning in your sea service to as complicated as numerous open book take home exams and STCW training courses. For an in-depth guide on the USCG license renewal process, eligibility criteria, and essential steps, explore our comprehensive resource. The detailed guide linked above has everything you need to know to stay current, helping you remain at the helm of your maritime career and your USCG credentials.

Some additional FAQ –

How long does it take to get a merchant Mariners credential?

Based on guidance from the USCG National Maritime Center, it's advisable to allow a minimum of 90 days for your USCG license to be processed once your application is submitted. However, MM-SEAS USCG licensing software customers who meet all qualification requirements can expect a significantly faster timeline. In our experience, the entire process typically takes around 5-7 weeks when we submit meticulously prepared applications that align perfectly with the work orders the REC and National Maritime Center evaluators are using. This streamlined approach significantly reduces the wait time from several months to just a few weeks.

It's a good idea to apply early—submit your application at least 90 days before you think you'll need the credential for work as it took the Coast Guard an average of 65 days to process applications for Merchant Mariner Credentials (MMCs) in 2022. Keep in mind that processing times can vary.

Need to renew, upgrade or get your first USCG license? We're here to help.

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About the author

Nate Gilman
Nate Gilman

Nate has over 15 years of professional maritime experience and has hawsepiped his way to a 3rd Mate Unlimited Endorsement with full STCW compliance. He is proud veteran of the NOAA Commissioned Corps.

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