Sea-time calculator

Quick answer

How much sea time do I need for a captain's license?

The OUPV (Operator of Uninspected Passenger Vessels, six-pack) and Master 25 to 100 Ton routes require 360 days of documented sea service since your 16th birthday, of which 90 days must fall inside the recency window. A day counts for 4 or more hours underway, capped at one day per calendar date. This calculator applies those rules to your own voyages.

Last reviewed 2026-07-22 by Captain's License Prep editorial team

Enter your voyages

Add a row per trip or per stretch of similar days. Hours per day is your typical time underway on that trip. Everything stays on your device.

License tier you are targeting Recency window (unresolved in the rules, set your assumption)

Estimates creditable sea time from the public rules for planning only. It is not legal advice and it does not issue or guarantee any credential: the National Maritime Center makes the final determination. Document your time on Form CG-719S.

How a day of sea time is credited

The day rule. A day of sea service is a day underway. The standard is an 8-hour day; for the OUPV and Master 25 to 100 Ton routes the National Maritime Center credits a day for a minimum of 4 hours underway.
Calendar dedup. You are credited no more than one day per calendar date, even if you served on two vessels that day.
The 360 and 90. The route needs 360 total documented days since your 16th birthday, with 90 of them recent. The exact recency-window length is not stated consistently across the public sources, so treat it as an assumption to confirm.
Water type matters. Near-coastal and ocean days qualify you for the Near Coastal route and the tonnage tiers; inland and Great Lakes days count toward the Inland route. The calculator splits your days so you can see both.
Documentation. Time is recorded on Form CG-719S, signed by the vessel owner or operator, or self-certified for a vessel you own.

Frequently asked questions

How does the Coast Guard count a day of sea time?

One day of sea service is credited for a day underway. The standard measure is an 8-hour day, and for the OUPV and Master 25 to 100 Ton routes the National Maritime Center credits a day for a minimum of 4 hours underway. You never earn more than one day per calendar date, even if you worked on two vessels that day.

Is this sea-time calculator free?

Yes. It runs entirely in your browser with no signup, no email, and no paywall. Your voyage dates stay on your device; when you calculate we receive only an anonymous, banded summary such as the tier you targeted and whether you met the recency window, with no identifier. See our privacy policy.

Does the calculator decide whether I get my license?

No. It estimates creditable sea time from the public rules so you can plan, but the National Maritime Center makes the final determination on every application. Documented sea time is submitted on Form CG-719S, signed by the vessel owner or operator, or self-certified for a vessel you own.

Why does the recency window ask me to choose 3 or 7 years?

The public sources disagree on how far back the required recent days may fall, and initial-issuance recency differs from renewal recency. Rather than hard-code a number that may be wrong for your case, the tool exposes it as a labeled assumption you set, and we verify it against 46 CFR 11 and the NMC checklist before relying on it.