What Master 25 GT lets you operate#
Master 25 GT covers inspected passenger vessels up to 25 gross tons on the route printed on the credential. It is different from OUPV/Six-Pack: OUPV is for uninspected passenger vessels carrying six or fewer passengers for hire, while a Master endorsement is the path for inspected passenger vessels and larger passenger counts.
For many inland lake, river, harbor-tour, launch, and small sightseeing operations, the business question is not whether Master 100 sounds better; it is whether the vessel's Certificate of Inspection and actual gross tonnage require more than 25 GT. If the vessel is under that limit, Master 25 can be the correct endpoint rather than a consolation prize.
Under the Inland Navigation Rules, three short blasts on the whistle by a power-driven vessel indicates which of the following?
Sea-time requirements by route#
The route comes first. Current NMC guidance for Master less than 100 GRT Great Lakes/Inland lists 360 total days of service; Great Lakes authority needs 90 of those days on Great Lakes waters. Near-Coastal Master less than 100 GRT uses 720 deck-department days, with ocean, near-coastal and Great Lakes service all credited day for day and only inland service other than the Great Lakes capped at 360 of the 720 (46 CFR 11.401(e); the NMC Near-Coastal checklist is worded the same way) — Great Lakes time counts toward the base requirement, not against a substitution ceiling.
For an original national officer endorsement, the NMC now applies USCG Policy Letter 02-25: at least 90 days of qualifying service within the 7 years immediately before application. The NMC applies the appropriate-tonnage test for the credential sought, so the recent days still need to be creditable toward Master 25. This recency check is separate from both the total route requirement and the tonnage limit. A candidate can have enough days for Master Inland or Master Near-Coastal and still receive a 25 GT limit if the documented vessels are too small to support 50 or 100 GRT. For what counts as a sea-service day and how to record each vessel's gross tonnage on CG-719S, see the USCG sea time requirements guide.
Why the limit lands at 25 GT#
A 25 GT limitation usually means the sea-service days support a Master endorsement but the vessel-size history does not clear the higher tonnage bands. Under 46 CFR 11.422 and the current NMC tables, the Coast Guard evaluates how much qualifying service was earned on larger vessels before assigning 25, 50, or 100 GRT.
The practical cutoff to remember: the NMC checklists tie 50 GRT to documented time on 17+ or 26+ GRT vessels, with the exact day threshold depending on route. If your valid Master service is mostly on smaller boats, the evaluator can issue 25 GT even though your route service is otherwise acceptable.
Exam and application sequence#
Master 25 GT uses the same Master less-than-100 framework as Master 50 and Master 100. Original applicants should expect Master-level modules such as Rules of the Road, Deck General, Deck Safety, Navigation General, and, for Near-Coastal routes, chart plotting. The Approval to Test letter is the controlling document for your exact module list.
The rest of the package is the same Merchant Mariner Credential workflow: CG-719B application, CG-719K medical certificate or valid medical certificate, drug-test evidence or enrollment, TWIC status, CPR/First Aid where required, sea-service documentation, and the applicable NMC fees.
When to upgrade from 25 to 50 or 100 GT#
Upgrade only when the operation needs it and your vessel history supports it. If the boat is larger than 25 GT, carries a passenger count that needs an inspected-vessel Master, or the business plan is moving into larger tour boats, begin collecting sea-service letters that show the vessel name, official number or registration, route, dates, hours, and gross tonnage.
The upgrade path is usually not about repeating all of your sea time from scratch. It is about proving additional qualifying service on larger vessels and passing any exam modules required by the NMC for the raise in grade, increase in scope, or route change.