The third engineer keeps the ship's electricity flowing. On most ships the generators and their engines are the third engineer's machines, together with a share of the auxiliary plant — the boilers, compressors or purifiers, depending on the company. It is the rank where an engineer stops being the newest officer below and starts being responsible for systems the whole ship depends on. This guide covers the duties, the watch, a typical day, the certificate, the interview and the step to second engineer.
What the third engineer does
- Generators. Running, load sharing, maintenance and overhauls of the auxiliary engines that drive the generators; records of running hours and performance.
- Auxiliary machinery. Depending on the company: boilers, air compressors, fuel and lube oil purifiers, fresh water generator, pumps.
- Watchkeeping or duty. On manned engine rooms the third engineer often keeps the 00:00–04:00 and 12:00–16:00 watch; on UMS ships engineers work by day and take turns as duty engineer at night, answering every alarm.
- Planned maintenance. Carries out and records the jobs on their machinery in the planned maintenance system.
- Bunkering and transfers. Often assists with bunkering, soundings and internal fuel transfers.
- Safety. Engine-room rounds, fire-fighting equipment below, and the engine team's roles in drills.
A typical day
- Manned engine room: 00:00–04:00 and 12:00–16:00 on watch, with maintenance on own machinery outside the watch.
- UMS ship: 08:00–17:00 day work with the second engineer and the crew, then — on duty days — the evening round and alarms through the night.
Manoeuvres, bunkering and breakdowns come at any hour; a generator problem is usually the third engineer's first call.
Differences by vessel type
- Container ships: large generators feeding reefer containers — power demand that never stops.
- Tankers: boilers and steam systems for cargo heating and pumps are often part of the job.
- Gas carriers: dual-fuel generators, high voltage, and gas safety systems.
- Offshore: diesel-electric plants where the generators are the propulsion — load management matters for DP.
- Passenger ships: many generators and big hotel loads; often several third engineers.
Certificates and documents
- Certificate of competency, officer in charge of an engineering watch (STCW III/1, 750 kW or more) — revalidated every five years.
- Flag endorsements (STCW I/10).
- Medical certificate — valid for at most two years.
- Basic Training refreshers every five years; Advanced Fire Fighting, Medical First Aid, PSCRB.
- ERM, High Voltage where the ship has it; for tankers and gas carriers the basic cargo courses; for gas-fuelled ships IGF.
What it takes
Under STCW Regulation III/1, the officer in charge of an engineering watch must be at least 18 and have combined workshop skill training and at least 12 months of approved sea service as part of an approved training programme with a training record book — or at least 36 months otherwise, of which at least 30 in the engine department — including at least six months of engine-room watchkeeping under supervision. The third engineer holds the same certificate as the fourth; experience is what separates them.
The path
Fourth engineer → third engineer → second engineer. The step to second engineer needs the III/2 certificate and at least 12 months of approved sea service as an engineer officer.
Contracts and rotation
Third engineers usually sail four to six months, sometimes longer. MLC 2006 limits time on board before repatriation to less than 12 months; the rest-hour minimums — 10 hours in 24 and 77 in seven days — apply even after a night of alarms on a UMS duty.
Interview questions for a third engineer
- "How do you parallel a generator onto the switchboard?" Voltage, frequency, synchroscope, load sharing.
- "A generator trips at sea — what do you do?" Standby start, preferential trips, finding the cause.
- "Boiler low water level alarm — your actions?"
- "Purifier overflowing — what do you check?"
- "What do you check on an engine-room round?" Pressures, temperatures, leaks, bilges, levels.
- "What does the oily water separator do, and what is the limit?" 15 ppm under MARPOL Annex I.
Common mistakes
- A CV that lists ships but not machinery — generator makes and models matter for this rank.
- No High Voltage course when applying to ships that need it.
- Weak electrical basics. Generator questions come in every interview.
- Courses expiring mid-contract.
FAQ
Do the third and fourth engineers need different certificates?
No. Both hold the STCW III/1 certificate; the difference is experience and duties.
Does the third engineer keep a watch?
On manned engine rooms yes, often the 00–04 watch; on UMS ships the third engineer takes turns as duty engineer.
How long until promotion to second engineer?
Usually after one or two contracts, once the second engineer's certificate is in hand.
What does UMS mean?
Unattended machinery space: the engine room runs without a watch at night, and the duty engineer answers alarms.
Pay and jobs
A step up from fourth engineer, and a big one again to second engineer. The current range from real vacancies is on the third engineer jobs page; a comparison by rank on our salaries page.
Your CV
Crewing desks read a third engineer's CV for engine and generator makes, power, vessel types and certificates with dates. The maritime CV puts them on one page.
Requirements follow STCW, MARPOL and MLC 2006; your flag state may add its own. Check them with your maritime administration.