What counts as a sea-service day#
NMC's current sea-service guide defines a standard day as 8 hours of watchstanding or day-working in an assigned deck or engineering position, not passenger time. For vessels under 100 GRT, NMC 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.
Do not assume a long day automatically gives extra credit. Time-and-a-half is limited to vessels and service letters that show an authorized two-watch system; ordinary overtime, recreational small-vessel days, and most under-100-GRT work are still credited as a single day.
To run your own logbook through these rules — creditable days, the route conditions, the 90-day recency screen, and the tonnage band the 46 CFR 11.422 formula assigns — use the sea time calculator. It keeps every entry in your browser.
When the Coast Guard issues a new MMC to a mariner before the existing MMC's expiration date, what is the status of the previously issued MMC?
Recreational vs commercial#
Recreational sea time on your own boat counts — provided it is documented and signed by a witness who can attest to the dates and the operator role. Commercial time on a USCG-documented vessel can be verified by the owner or master.
CG-719S: the small-vessel sea-service form#
Use CG-719S for service on vessels of less than 200 GRT. Complete one form per vessel, list the body of water, official or state registration number, vessel dimensions and gross tons, propulsion, capacity served, days by month and year, average hours underway, Great Lakes days, and days shoreward or seaward of the boundary line.
Who may attest is set by 46 CFR 10.232(a)(4), and it turns on ownership rather than on the form: for service on vessels of less than 200 GRT, owners may attest to their own service and provide proof of ownership, while applicants who do not own the vessel must obtain letters or other evidence from credentialed personnel or from the owners of the vessels listed. Above 200 GRT there is no CG-719S path — the service is proved with certificates of discharge, official letters, or comparable documents instead.
CG-719S is a container, not a licence to skip the content rules. Whatever you attach to it is still documentary evidence under 46 CFR 10.232(a)(2) and has to carry the eleven items below unless it is a Certificate of Discharge conforming to 46 CFR 14.307.
The same form matters later if you renew on recent service: the USCG captain's license renewal forms guide explains where CG-719S fits in the 5-year renewal package.
The sea service letter: the eleven items 46 CFR 10.232 requires#
A sea service letter is any documentary proof of sea time that is not a Certificate of Discharge — a signed letter from a marine company, a service log, a pilotage billing form. As of 2026-08-06, 46 CFR 10.232(a)(1) accepts all of those, provided the letter is signed by the owner, operator, Master, or Chief Engineer of the vessel and the Coast Guard is satisfied as to its authenticity.
There is no official USCG sea service letter template, and that is why letters get returned. What exists instead is a content requirement: unless your evidence is a Certificate of Discharge conforming to 46 CFR 14.307, 46 CFR 10.232(a)(2) says it must contain all of the following — (1) vessel name(s) and the official numbers listed on the registration, certificate, or document issued; (2) gross tonnage of the vessel; (3) propulsion power and mode of propulsion; (4) the amount and nature of your experience, naming the position served; (5) applicable dates of service for each vessel, and the ports or terminals if applicable; (6) the routes upon which the experience was acquired; (7) for a Radar Observer renewal, whether the vessel carried radar and whether you served in a position that routinely used it for navigation and collision avoidance; (8) for towing-vessel credit under 46 CFR 11.211(e), the aggregate tonnage of the tug and barges during your service; (9) any other information needed to determine whether STCW applies to the vessel; (10) whether the vessel is manned and equipped in accordance with SOLAS; and (11) where an officer endorsement requires it, time served on bridge or engine watchkeeping duties under the supervision of a qualified officer.
Two items decide most rejections. Routes (6) is the one evaluators cannot infer: an oceans or near-coastal claim credited under the day-for-day limits above needs the letter to say where the vessel actually ran, not just that it ran. And the position in (4) has to be a deck or engineering assignment — a letter that says you were "aboard" documents passenger time, which earns no credit.
Supervised service carries an extra burden. Under 46 CFR 10.232(a)(5), where the endorsement's watchkeeping or duty requirements come from 46 CFR 11.323, 11.329, 11.333, 11.470, 11.472, or 11.474, the letter must state on its face that the service was carried out under the supervision of the appropriate person. If you have been working as a Pilot, 46 CFR 10.232(a)(6) lets a pilots' association letter attest to the service, and pilots outside an association may submit billing forms or comparable records — but a raise of grade still has to meet the eleven-item list.
Because 46 CFR 11.211(a) sends officer-endorsement applicants to 46 CFR 10.232 for all documentation questions, this list governs every national officer endorsement, from OUPV up. Run the days themselves through the sea time calculator first, then write the letter to match what the calculator shows.
Near-Coastal vs Inland time#
OUPV Near-Coastal requires 12 months of vessel-operating experience, including at least 3 months on ocean or near-coastal waters. OUPV Inland requires 12 months of vessel-operating experience on inland waters. For any original national officer endorsement, current USCG Policy Letter 02-25 treats the recency requirement as at least 3 months (90 days) of qualifying service on appropriate vessels within the 7 years immediately before you apply. Current NMC OUPV and Master checklists use that seven-year window even though the underlying 46 CFR 11.201(c) text still describes a three-year window for most non-uniformed-service applicants.
The 90-day recency check is separate from the route-specific totals. For oceans, near-coastal, or STCW endorsements, 46 CFR 11.211 credits Great Lakes service day-for-day up to the full requirement, while inland waters other than the Great Lakes may credit day-for-day for up to 50% of the total required service. Track Great Lakes, inland, ocean, and near-coastal days separately on your forms so the evaluator can apply those limits correctly. The same day count feeds the Master routes and tonnage bands — see how it maps to the 100-ton Master captain's license requirements once your service is in hand.