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  • Nate Gilman

Sea Time Requirements for 100 Ton Master

The US Coast Guard requires that all captains must provide the minimum requirement of sea time to get their masters or USCG license. Where you are sailing, the number of days you have in your life and the size of the boat all determine what initial USCG license you qualify for.



You must have at least 360 days of sea time for Inland.

If you have at least 360 days on the water with 90 of those days in the last 3 years you can qualify for a 100 ton master inland.


Depending on the size of your vessels you will initially qualify for either a

  1. 100 ton master – which requires 90 days of service on vessels of 51 GRT or above, OR 180 days of service on vessels of 34 GRT or above

  2. 50 ton master – which requires 90 days of service on vessels of 26 GRT or above OR 180 days of service on vessels of 17 GRT or above

  3. 25 ton master – you will be issued a 25 ton master if you do not qualify for 50 ton master or a 100 ton master


You must have at least 720 days of sea time with 360 days out on the ocean for Near Coastal.

If you have at least 720 days on the water with 360 days on ocean and 90 of those days in the last 3 years you can qualify for a 100 ton master near coastal.


Depending on the size of your vessels you will initially qualify for either a

  1. 100 ton master – which requires 180 days of service on vessels of 51 GRT or above, OR 360 days of service on vessels of 34 GRT or above

  2. 50 ton master – which requires 180 days of service on vessels of 26 GRT or above OR 360 days of service on vessels of 17 GRT or above

  3. 25 ton master – you will be issued a 25 ton master if you do not qualify for 50 ton master or a 100 ton master


The size of the vessels you are on determines how large of a USCG license you are first issued.


No matter if you initially qualify for a 25 ton master or 50 ton master instead of the 100 ton master, you are 90 days away from upgrading to the next one on the same route.


After your master license has been issued you can easily increase your masters license from 25 ton to 50 ton or 50 ton to 100 ton by having 90 sea days on any vessel in any deck position on any waters while holding your current masters license per 46 CFR 11.422.


This means if you get your 25 ton master all you need to do is get 90 more days on any vessel in any deck position on any waters while holding your current masters license to upgrade to a 50 ton master on the same route.


The same is true when you get your 50 ton master. All you need to do is get 90 more days on any vessel in any deck position on any waters while holding your current 50 ton masters license to upgrade to a 100 ton master on the same route.



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 office hours Monday and Wednesday from 5:00 - 5:30 pm PT inside of mmseas.com under License Guidance and then Daily Office Hours.


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.

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