Entry & progression
The most common reason a yacht engineer never starts a USCG credential is a belief that the time will not count. It counts. This lesson gives you the sentence to quote and the axes the time is measured on.
What the NMC actually says
From the NMC's own guidance on crediting sea service, verbatim: "Sea service is a measure of a mariner's lifetime experience on boats, whether recreational, commercial, or military. It may be counted from the day a mariner turns age 16."
Read the middle of that sentence again. Recreational. A private yacht is a recreational vessel, and the NMC's own words put recreational service in the same breath as commercial and military. And the clock starts at 16 — earlier than most people expect, and worth knowing if you grew up around boats.
The silence in the regulation is not a prohibition
Here is the thing that surprises people who go looking. The words yacht, recreational and pleasure appear zero times in the whole of 46 CFR Part 10. Not once. The regulation that governs the crediting of sea service simply does not mention yachts.
That silence is routinely misread as exclusion. It is the opposite. Part 10 does not exclude yacht service — it does not name it, because it does not categorise service by the vessel's social purpose at all. It categorises service by what the vessel is and where it went.
The axes your time is actually measured on
- Route — inland, near-coastal, oceans. Where the vessel operated, not where she was registered.
- Tonnage — and on the engineering side, this caps the lower grades rather than defining them.
- Propulsion power — the engineering unit. Main propulsion machinery only.
- Capacity served — Wiper, QMED, engineer officer. What you were doing, not what the crew list called you.
- Hours per day — the 8-hour day of the last lesson.
Every one of those is a fact about the vessel and your job on her. None of them is a fact about whether guests paid to be aboard. A 3,000 kW motor yacht crossing an ocean and a 3,000 kW tug crossing the same ocean present the evaluator with the same numbers on the same axes.
TIP — Propulsion power means the mains — and only the mains This is the axis yacht crew get wrong most often. Propulsion power is the total maximum continuous-rated output of the main propulsion machinery, and 46 CFR 10.107 says it "excludes thrusters and other auxiliary machinery." Your gensets, your bow and stern thrusters and your hydraulic plant do not count toward it — however much of your working life they consume. A yacht with an enormous electrical plant and modest mains sits lower on this axis than her crew assume.
CAUTION — Counting is not the same as evidencing That yacht time counts in principle is settled. Whether your time is credited depends entirely on how it is documented and who signs for it — and that is where most yacht service actually fails. The next lesson is the one that saves the year.