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

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.

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.

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.

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 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.

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.

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.

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.