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USCG sea time calculator. Days, route, and tonnage.

Log your service one vessel at a time and see what the Coast Guard will actually credit: days under the 8-hour rule, progress toward each OUPV and Master route, the 90-day recency screen, and the 25 / 50 / 100 GRT band the 46 CFR 11.422 formula assigns you. Everything stays in your browser.

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Add a block of service

One row per vessel and water body — the same way CG-719S wants it. Everything stays in this browser.

Creditable days

0

Total

0

Ocean / near-coastal

0

Great Lakes

0

Inland

Within the last 7 years: 0 of the 90 days the NMC wants recent — not met yet (Policy Letter 02-25).

Where that puts you

Your likely tonnage band

The 25 / 50 / 100 GRT limit on a Master credential is not chosen — it is computed from the size of the vessels in your qualifying service under 46 CFR 11.422. Because the formula uses the required days for the credential you are seeking, the same logbook can produce different bands for different routes.

Not enough creditable service yet to compute a band. The formula needs service on vessels totalling at least 25% of the 360-day requirement (that is 90 days) before any tonnage falls out of it.

46 CFR 11.422 also lets you raise a limit with additional service — 90 days as Master in your highest authorized tonnage, or 6 months of extra deck-department service for a one-increment increase. The NMC applies the formula to your documented service, so the band on your credential can differ from this estimate.

Take it to your application

Copy a per-vessel worksheet — days, hours, waters, tonnage, and the credited totals — in the order CG-719S asks for them. It is a worksheet, not a substitute for the form.

Open form CG-719S

Educational estimate, not a credentialing determination. The Coast Guard National Maritime Center makes the final call on creditable days, route, and tonnage after reviewing your documented service. Your entries are stored only in this browser — clearing site data deletes them, and nothing is sent to us.

How the Coast Guard counts your days

Three rules decide whether a day in your logbook survives an evaluator, and a fourth decides how big a vessel your credential lets you run. Most applications that stall do so on one of them — not on the total.

The 8-hour day

46 CFR 10.107 makes a day 8 hours of watchstanding or day-working, excluding overtime. Under 100 GRT, the NMC may credit a full day for 4+ hours; under 4 hours earns nothing. A 14-hour day is still one day without a documented two-watch system.

Route conditions, not just totals

Every route above inland is bought with 3 months on the water it authorizes — ocean or near-coastal days for Near Coastal, Great Lakes days for the Great Lakes. An inland-only logbook can hold 900 days and still not reach those routes.

The substitution ceiling

For Master Near Coastal, 46 CFR 11.428 lets Great Lakes and inland service substitute for at most 1 year of the 2 years required. Everything past that ceiling is real experience that earns no credit toward this endorsement.

Tonnage is computed, not requested

46 CFR 11.422 derives the 25 / 50 / 100 GRT limit from the size of the vessels in your qualifying service. Service concentrated on small boats caps the credential — over 75% on vessels of 5 GRT or less limits it under 25 GRT automatically.

Frequently asked

How many hours count as a day of sea time?
46 CFR 10.107 defines a day as 8 hours of watchstanding or day-working, not including overtime. On vessels of less than 100 GRT the National Maritime Center may credit a full day for 4 or more hours when the vessel's operating schedule makes the 8-hour standard inappropriate; service under 4 hours receives no credit at all. A long day does not earn extra credit unless the vessel runs a documented two-watch system, and you can never count more than one day in a 24-hour period.
How much sea time do I need for an OUPV six-pack?
Since the 25 November 2024 amendment, 46 CFR 11.467 states the requirement in months: 12 months of experience in the operation of vessels, which is 360 days at 46 CFR 10.107's 30-day month. Near Coastal adds at least 3 months of that service on ocean or near-coastal waters; the Great Lakes route adds 3 months on Great Lakes waters; Inland has no additional water condition.
How much sea time does a Master less than 100 GRT need?
It depends entirely on the route. Master Inland is 1 year (360 days) of service on any waters under 46 CFR 11.457. Master Great Lakes and Inland is 1 year of total deck service under 46 CFR 11.455, of which 3 months must be on Great Lakes waters or the endorsement is limited to inland waters. Master Near Coastal is 2 years (720 days) of deck service on ocean or near-coastal waters under 46 CFR 11.428, and Great Lakes plus inland service may substitute for up to 1 year of it — which is why an all-inland logbook stalls at 360 credited days for that route no matter how many days it holds.
How is my 25, 50, or 100 GRT tonnage limit decided?
By formula, not by choice. Under 46 CFR 11.422 the endorsement is limited to the maximum gross tonnage on which at least 25 percent of the required experience was obtained, or 150 percent of the maximum tonnage on which at least 50 percent of the service was obtained — whichever is higher — then rounded-sm up to the 25, 50, 100, or 200 GRT band. If more than 75 percent of your qualifying experience is on vessels of 5 GRT or less, the credential is automatically limited to vessels under 25 GRT. Because the first test measures against the required days, the same logbook can yield a lower band for a 720-day route than for a 360-day one.
Does my sea time expire?
The days themselves do not expire, but recency is checked separately. USCG MMC Policy Letter 02-25 has the NMC look for at least 90 days of qualifying service in the 7 years immediately before you apply, and current OUPV and Master checklists apply that window. Old service still counts toward the route total; it just cannot satisfy the recency screen on its own.
Does recreational time on my own boat count?
Yes, when it is documented. Time operating your own vessel counts if it is recorded and attested by someone who can vouch for the dates and your role — the owner, master, or another person with knowledge of the service. Use form CG-719S for vessels of less than 200 GRT, one form per vessel, and attach proof of ownership if the boat is yours. Passenger time never counts.
Is this calculator an official Coast Guard determination?
No. It applies the published rules in 46 CFR Parts 10 and 11 plus current NMC policy to the numbers you enter. The National Maritime Center makes the final decision on creditable days, route, and tonnage after reviewing your documented service. Where a rule is discretionary — the under-100-GRT 4-hour credit, time-and-a-half — this tool withholds the credit rather than promising a day the NMC has not agreed to.

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