Nate Gilman
Which is better? A Merchant Mariner Credential (MMC) or a U.S. Coast Guard (USCG) License?
A Merchant Mariner Credential (MMC) and a U.S. Coast Guard (USCG) License are the same thing! Technically the phrase USCG License is considered a legacy term, we still use it within the maritime community.

So what is a Merchant Mariner Credential (MMC)?
An MMC is issued by the U.S. Coast Guard (USCG) in accordance with Federal regulations. Each MMC describes the type(s) of vessel(s), tonnage(s), horsepower(s), and waters (routes) for which the mariner is qualified. For service in international waters, the MMC would include appropriate endorsements according to the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW).
Do I need an USCG License or MMC to work on boats?
It depends, if you are working on a United States (U.S.) merchant vessel that is greater than 100 Gross Register Tons (GRT) you are required to have a valid U.S. MMC. This means everyone from the Steward to the Captain has to have a valid MMC on them at all times. The only exception to this 100 GRT rule is operators of uninspected passenger vessels. If you are working on vessels less than 100 GRT there are certain positions which are required to have a valid MMC which are clearly laid out in the vessels safe manning document. It's typical for only the Captain on a vessel less that 100 GRT to hold a USCG License while the crew does not hold a valid MMC.

We hope this made your life a little easier and if you have other questions the MM-SEAS team is always here to help!
We do prefer to answer questions live with screen sharing to make both of our lives easier.
We hold free live virtual master classes Monday and Wednesday from 5:00 - 5:30 pm PT inside of mmseas.com under License Guidance and then Daily Master Classes.
Pro MM-SEAS members get access to our daily live office hours Monday thru Friday from 5:00 - 5:30 pm PT. You also get access to unlimited live 1 on 1 calls with one of our USCG Licensing Specialists. Pro MM-SEAS members can access these features inside of mmseas.com under License Guidance.