Entry & progression
Time on deck can be credited toward an engineer endorsement. How much depends entirely on which endorsement you are chasing. There is no single number, and anybody who gives you one is guessing.
This matters more on yachts than anywhere else, because yacht careers are messy. People arrive as deckhands, drift into the engine room, cover both, and end up with a service record that is genuinely mixed. The Coast Guard will credit some of that deck time — but it prices it differently at every rung of the ladder, and the differences are not small.
The table — and this is the whole lesson
| Endorsement sought | Deck credit allowed | Citation |
|---|---|---|
| Third Assistant Engineer | up to 3 months, on vessels of 100 GRT or more | 11.516(b) |
| Chief Engineer-Limited / Assistant Engineer-Limited / DDE | up to 25% or 6 months, whichever is less | 11.504 |
| STCW OICEW (III/1) | up to 3 months | 11.329(b) |
| STCW Chief Engineer, 750–3,000 kW | up to 2 months | 11.331(a)(1) |
| STCW Second Engineer, 750–3,000 kW | up to 1 month | 11.333(a)(1) |
Five rungs. Five different answers. One number will not cover them all, and the spread runs from a single month to six.
What the pattern tells you
Read the table as a statement of intent and it stops looking arbitrary. The Coast Guard is willing to concede that a deckhand on a working vessel learns something transferable — seamanship, watch discipline, how a ship behaves. It is not willing to concede that deck time teaches you the plant. So the allowance is real, and it is small, and it shrinks as you climb.
Notice where it is largest. The Limited grades and DDE get the most generous treatment — 25% or 6 months, whichever is less — and those are the small-vessel, sole-engineer rungs where a mixed background is normal. Notice where it is smallest: one month toward STCW Second Engineer on the 750–3,000 kW ticket. By the time you are asking to be the number two of a department, the Coast Guard has almost stopped counting your deck time.
WARNING — Read '25% or 6 months, whichever is less' properly It is a cap on a cap. Twenty-five percent of the required service, but never more than six months — so on a rung requiring three years, 25% would be nine months and the six-month ceiling cuts it back. On a rung requiring one year, 25% is three months and that is the binding limit. Always compute both and take the smaller.
NOTE — The Third Assistant Engineer route carries a tonnage condition 11.516(b) allows up to 3 months of deck credit — but only for deck experience on vessels of 100 GRT or more. Deck time on smaller boats does not buy you into the unlimited ladder. It is the same instinct as the walk-in engine room test: the Coast Guard wants the experience to have happened on something substantial.
CAUTION — Do not plan a career around deck credit The allowances above are ceilings, not entitlements, and whether a particular period of deck service is creditable at all is an evaluator's judgment. Deck credit is a way to recover a few months of a mixed history — it is not a route. If your plan depends on the maximum being granted, confirm it with the NMC before you commit to it.