How Much Sea Time Do You Need for Each USCG License?

Passing the exam is only half of earning a Coast Guard license. The other half is proving you've actually been on the water — your sea service. More applications stall over sea time than over the test, usually because the days weren't documented right or didn't meet the recency rule. Here's exactly how much you need for each credential and how to make it count.

What Counts as a Day of Sea Time

The Coast Guard defines a day of sea service as at least 4 hours underway on a vessel. Underway means not moored, anchored, or aground — the vessel is actually operating. A single calendar day can only ever count as one day, no matter how many hours you put in, and the National Maritime Center (NMC) does not count fractional days beyond that 4-hour threshold.

Two things matter just as much as the raw count:

• It has to be documented. Sea service is proven with a signed letter from the vessel owner or operator (or your own logbook for vessels you owned/operated), transcribed onto Form CG-719S. Undocumented time doesn't exist as far as the NMC is concerned.
• It has to be recent enough. Most credentials require a portion of your total days to fall within the last few years. Old time alone won't qualify you.

The 90-Day Recency Rule

For an original (first-time) license, the NMC generally wants to see at least 90 days of your total sea service within the last three years. You can have hundreds of days from a decade ago, but if you haven't been on the water recently, you'll need to rebuild that recent block before you qualify.

This is the single most common reason an otherwise-ready applicant gets held up. Track total days and recent days separately so you always know where you stand — the Binnacle School sea time tracker breaks both out for you and flags when the recent minimum is met.

Sea Time by License

These are the headline minimums. Real requirements shift with route (inland vs. near-coastal vs. ocean) and tonnage, so always confirm the specifics for your situation with the NMC.

OUPV / 6-Pack

• 360 days total, with at least 90 within the last 3 years.
• For the near-coastal route, a portion of those days must be on the ocean or near-coastal waters; the inland route is logged on inland waters.
• This is the most attainable threshold and why the OUPV is the entry point for most mariners.

Master 25 / 50 / 100 Ton

• 360 days total for the base license, again with 90 recent.
• Tonnage is set by the size of the vessels your documented time was earned on — your license is limited to roughly the tonnage you can prove experience on, so logging time on bigger boats matters if you want a higher tonnage.
• Near-coastal Master adds offshore-day requirements on top of the base count.

Master 200 Ton

• 720 days total is the common benchmark, with 90 recent.
• Higher tonnage and near-coastal/ocean routes carry their own offshore-day expectations, and the exam itself adds Celestial Navigation and Radar Observer.

Merchant Mariner Credential (MMC) and Upgrades

• Requirements vary widely by the specific officer endorsement, tonnage, and route — there's no single number. A common entry baseline is around 360 days, but mate and master upgrades on larger tonnage can require far more, much of it on specific routes.
• This is the credential where you most want to confirm the exact requirement before you start gathering letters.

How to Document It Right

1. Log as you go. Record vessel name, dates, route, and your role for every trip. Reconstructing two years of trips from memory the week before you apply is miserable and error-prone.
2. Get sea service letters. For vessels you didn't own, you need a signed letter from the owner or operator confirming your time. Ask while you still have the relationship — chasing a former employer for a letter a year later is hard.
3. Transcribe onto CG-719S. The form is where your days officially live. Keep your underlying logs and letters as backup in case the NMC asks.
4. Watch the clock on recency. If your recent days are thin, prioritize getting back on the water before you apply.

Common Sea-Time Mistakes

• Counting dock days. Time moored or at anchor isn't underway and doesn't count.
• Double-counting a day. Two trips on the same calendar day is still one day.
• Letting it lapse. Hitting 360 total means nothing if you don't also have 90 in the last three years.
• No paper trail. Verbal assurances from a captain won't satisfy the NMC — get it in writing.

Track It, Then Test

Sea time is a marathon you run in the background while you study. Keep a running tally so the requirement never sneaks up on you — the sea time tracker logs your voyages, watches the recency rule, and exports a clean summary to copy onto Form CG-719S. When your days are in order and you're ready to tackle the written exam, the Binnacle School question bank covers every category for your license.

Binnacle School is a study and planning resource and is not affiliated with the USCG or the National Maritime Center. Always confirm current requirements at uscg.mil/nmc.