How sea time works for the captain's license

Sea time is the requirement that stalls more captain’s license applications than any exam question. The rules are simple to state and easy to get wrong in practice: you need enough total days, enough of them recent, earned on the right kind of water, and documented on the right form. This guide walks through each rule, and the free sea-time calculator applies all of them to your own list of voyages so you can see exactly where you stand.

The credential itself is a U.S. Coast Guard Merchant Mariner Credential (MMC) with an Operator of Uninspected Passenger Vessels (OUPV) or Master officer endorsement, issued by the National Maritime Center (NMC). Sea-time rules come from Title 46 of the Code of Federal Regulations (CFR) Part 11 and the public NMC checklists. This site is independent and is not the Coast Guard, the NMC, or a course provider.

How many days of sea time do you need?

For the OUPV (six-pack) and the Master 25, 50, or 100 ton routes, you need 360 days of documented sea service, counted since your 16th birthday. That is the headline number nearly every source agrees on. A day here is a day underway, not a calendar day you happened to own a boat, and it is documented, not estimated after the fact.

Three hundred and sixty days sounds like a full year, but it does not have to be one continuous year. It is a running total across your whole boating life from age 16 forward, assembled from every qualifying trip. Most applicants reach it by adding up years of weekend and seasonal outings rather than a single job.

What counts as one day of sea time?

The standard measure is an 8-hour day underway. For the OUPV and Master 25 to 100 ton routes, the NMC will credit a full day for a minimum of 4 hours underway. So a 4-hour afternoon on the water counts as one day, and so does a 10-hour day: you never earn more than one day of credit per calendar date, no matter how many hours you were out.

That last rule is the one people miss. If you ran two charters on the same date, or served on two vessels in one day, it is still one day of sea-time credit. The sea-time calculator enforces this calendar deduplication automatically, so overlapping trips never inflate your total.

A quick way to reason about it:

• Under 4 hours underway on a given date: no credit for that date.
• 4 hours or more, once in a date: one day of credit.
• Two trips totaling more than 8 hours in one date: still one day of credit.

What is the 90-day recency requirement?

Of your 360 total days, at least 90 must be recent, falling inside a rolling recency window that ends today. This is the rule that catches people who earned their sea time years ago and then took time off the water. You can have 800 lifetime days and still fall short if fewer than 90 of them are recent enough.

There is an honest complication here, and we will not paper over it: the public sources disagree on how long the recency window is. Some course-seller pages say the last three years, others say the last seven, and the recency rule for an initial license differs from the recency rule at renewal. Rather than print a single number that might be wrong for your situation, the sea-time calculator exposes the window as a labeled assumption you set yourself, and this figure carries a verify note against 46 CFR 11.201 and 11.211 and the NMC OUPV checklist. Confirm the current window with the NMC or your evaluator before you rely on it.

The practical takeaway does not depend on the exact number: if you have been off the water for a stretch, log a few more recent qualifying days before you apply, because recency is the cheapest gap to close.

Does near-coastal or inland time matter?

Yes, and it decides which license you get. Sea time is split by water type:

• Near coastal and ocean days qualify you for the Near Coastal route and for the tonnage tiers (Master 25, 50, or 100 tons).
• Inland and Great Lakes days count toward the Inland route.

You can hold, for example, an OUPV Near Coastal only if enough of your documented days were earned on near-coastal or ocean waters. Someone with 400 days entirely on a lake qualifies for OUPV Inland, not Near Coastal, no matter how many days they have. The calculator splits your entered days by water type so you can see both totals at once and know which route your log actually supports. For the difference between the OUPV and Master routes, see OUPV vs Master.

How do you document sea time?

Sea time is proven on Form CG-719S, the Small Vessel Sea Service Form, signed by the owner or operator of each vessel you served on. If you owned the vessel yourself, you can self-certify your own time. Keep the forms organized by vessel, because the NMC evaluates the documented days, not the days you remember.

The CG-719 forms walkthrough covers exactly how to fill out the CG-719S, including the tonnage and water-type fields that determine your route. Sloppy or incomplete sea-service forms are a common reason an application bounces back for correction, which adds weeks to an already long wait (see the processing tracker for current NMC timelines).

How the calculator applies all of this

A chat answer can recite “360 days, 90 recent,” but it cannot take your specific list of messy trip ranges, apply the 4-hour minimum, deduplicate overlapping dates, split near-coastal from inland, run the recency window against today’s date, and tell you which tier you qualify for and what is still short. That is what the free sea-time calculator does. You enter each voyage (start date, end date or number of days, hours underway per day, water type, and vessel tonnage), and it returns your total creditable days, your recent-day count, your water-type split, and a plain readout such as “you qualify for OUPV Near Coastal but you are 40 days short for the 50-ton Master.” Everything runs in your browser; your trip dates never leave your device.

Sea-time requirements at a glance

• Total: 360 documented days since your 16th birthday.
• Recent: at least 90 days inside the recency window (window length unresolved in the public sources, treat as an assumption to confirm).
• A day: 4 or more hours underway, capped at one day per calendar date.
• Water type: near-coastal and ocean days unlock Near Coastal and the tonnage tiers; inland and Great Lakes days count toward Inland.
• Proof: Form CG-719S signed by each vessel’s owner or operator, or self-certified for a vessel you own.

Sources: 46 CFR Part 11 (11.201 and 11.211) via ecfr.gov, and the public National Maritime Center OUPV and Master checklists (dco.uscg.mil/nmc), verified 2026-07-22. The 360-day total, the 4-hour minimum, and the one-day-per-calendar-date cap are set by federal rule and the NMC. The exact length of the recency window is stated inconsistently across public sources and differs between initial issuance and renewal; it is presented here as an assumption to confirm with the NMC, not a fixed figure. The National Maritime Center makes the final determination on every application.