Third engineer duties and responsibilities centre on keeping an engine-room watch and maintaining assigned machinery, usually the boilers, auxiliary engines, fuel system and purifiers. The third engineer reports to the second engineer and holds an STCW officer-of-the-watch certificate.
This guide sets out the daily duties, maintenance and reports. It also covers the certificates needed in the US, UK, India and the Philippines.
What Is a Third Engineer on a Ship?
A third engineer is the third most senior engineer officer on a merchant ship, below the chief and second engineers. He or she keeps an engine-room watch, maintains assigned machinery and holds an STCW Regulation III/1 certificate of competency.
The rank usually wears two stripes. On US-flag ships the same job is often titled Second Assistant Engineer, while a new US academy graduate sails as Third Assistant Engineer.
How the engine department fits the rest of the crew is set out in our guide to ranks on merchant navy ships.
| Rank | Reports to | Typical machinery |
|---|---|---|
| Chief engineer | Master | Whole engine department, fuel and compliance |
| Second engineer | Chief engineer | Main engine, work planning, engine crew |
| Third engineer | Second engineer | Boilers, auxiliary engines, fuel system, often purifiers and air compressors |
| Fourth engineer | Second engineer | Purifiers, pumps, sewage and bilge systems on many ships |
What Are the Main Duties of a Third Engineer?
The main duties are keeping a safe engine-room watch, maintaining assigned machinery, managing fuel transfers and keeping logs and maintenance records. The exact split is set by the second engineer and the company.
- Fuel oil: keep the specified viscosity and temperature at the inlet to the fuel pumps, and drain water from the settling and service tanks daily.
- Auxiliary engines: check exhaust gas temperatures, lube oil temperatures and pressures, and the differential pressure across fuel and lube oil filters.
- Purifiers: operate the fuel oil purifiers at the correct temperature and throughput, and clean them on schedule.
- Water tests: test the high- and low-temperature cooling water and carry out boiler water treatment, then log the results on company forms.
- Soot blowing: blow soot from the exhaust gas boiler after informing the bridge, so deck and wind conditions are checked first.
- Air compressors: keep oil levels correct and check running condition, drains and unloaders.
- Emergency equipment: run assigned tests, such as the emergency generator, emergency fire pump, bilge alarms and engine-room fan dampers.
- Overhauls: assist with major repairs, including main engine work led by the second engineer.
- Reporting: report any defect to the second engineer at once, and to the chief engineer when it affects seaworthiness.
- Records: keep the engine log, fuel consumption figures, running hours and spare-part inventories up to date.
On some ships the third engineer also looks after deck machinery such as winches and cranes. Company circulars and technical bulletins must be read and followed as they arrive.
What Does a Third Engineer Do on Watch?
On watch, the third engineer monitors the running plant, takes rounds of the engine room, responds to alarms and records readings in the engine log. On a traditional watch system the third engineer often keeps the 12–4 watch.
- Take over the watch only after checking running machinery, tank levels and any defects with the outgoing engineer.
- Make rounds every watch: leaks, abnormal noise or vibration, temperatures, pressures and bilge levels.
- Answer bridge orders and alarms, and call the second or chief engineer when unsure.
- Hand over with a clear verbal and written report.
Many modern ships run unmanned machinery spaces (UMS). There, engineers work days and take turns as duty engineer at night, answering alarms in the cabin.
Watch and work hours are limited by rest-hour rules. The STCW Code requires at least 10 hours of rest in any 24 hours and 77 hours in any 7 days. The MLC 2006 sets the same rest limits, or equivalent maximum working hours.
How Does a Third Engineer Handle Fuel and Bunkering?
The third engineer prepares the fuel system for bunkering and sounds tanks before, during and after it. He or she also transfers fuel to the settling and service tanks.
The chief engineer is in charge of bunkering and plans each stem. Daily soundings give the remaining-on-board (ROB) figures the chief engineer uses for bunker requests. During bunkering on ships, the third or fourth engineer usually handles valves, vents and sounding pipes.
Fuel and sludge operations are recorded in the Oil Record Book Part I, required by MARPOL Annex I. The officer in charge signs each entry, and the master signs each page.
How Is Third Engineer Maintenance Planned and Recorded?
Maintenance runs through the ship’s planned maintenance system (PMS). The software lists jobs as they fall due by running hours or calendar dates, and the second engineer assigns them.
A PMS is how the ship meets the maintenance element of the ISM Code. Each finished job, and every spare part used, is recorded so the next port order is correct.
Most third engineers look after the auxiliary engines, purifiers, boilers and air compressors. Below are examples of that work before and after overhaul.
Fuel Oil Purifier Overhaul
Air Compressor Overhaul
Example of a PMS Screen
How Is Work Divided in the Engine Room?
The second engineer oversees and divides the work by the manpower needed and each engineer’s experience. Jobs are discussed at the engine toolbox meeting before they start.
Hot work and entry into tanks need permits to work. The permit, risk assessment and isolation are agreed before the job begins.
Which Reports Does a Third Engineer Prepare?
A third engineer prepares month-end reports for the company on the machinery, stores and tests in their charge. The list varies by company, but a typical set looks like this.
- Critical spares and critical special tools inventory
- Gases, chemicals and lube oil inventory
- Main engine and auxiliary engine running hours and performance reports
- Motor and pump maintenance report
- Critical alarm test report
- Boiler maintenance and alarm test report
- Air compressor maintenance and alarm test report
- Purifier maintenance report
- Heat exchanger maintenance report
- Water test and lube oil test reports
What Qualifications Does a Third Engineer Need?
A third engineer needs an STCW Regulation III/1 certificate as officer in charge of an engineering watch on ships of 750 kW or more. It requires approved training, 12 months of sea and workshop training, a medical and an exam.
- Age: at least 18 under STCW; national rules can be higher.
- Training: an approved programme with combined workshop training and sea service of at least 12 months, recorded in a training record book.
- Watchkeeping: at least 6 months of engine-room watchkeeping under supervision.
- Safety courses: basic training, survival craft, advanced fire fighting and medical first aid.
- Medical: a valid seafarer medical certificate.
The STCW route is explained in our guide to the STCW certificate of competency. Each country issues it through its own maritime authority.
| Country | Usual route to the certificate | Authority |
|---|---|---|
| United States | Engineering graduate of a maritime academy, or 1,080 days of engine-room service (720 as QMED), then the USCG exam for Third Assistant Engineer; minimum age 19 | US Coast Guard NMC (46 CFR 11.516) |
| United Kingdom | Approved cadetship (HND or Foundation Degree) with 12 months of sea and workshop training, then the MCA oral for Engineer Officer of the Watch | Maritime and Coastguard Agency (MSN 1857) |
| India | B.E./B.Tech Marine Engineering, or the 1-year GME course for mechanical engineers, then sea service and the MEO Class IV exam | DG Shipping (now DGMA) |
| Philippines | BS Marine Engineering plus 12 months of onboard training as engine cadet, then the OIC-EW exam and assessment | MARINA (STCW Circulars 2018-08 and 2018-09) |
US readers can compare the academy route in our guide to maritime colleges and academies in the US. The US Bureau of Labor Statistics gives a median of $109,530 a year for all ship engineers (May 2025).
What Is the Difference Between a Third and Fourth Engineer?
The third engineer is senior to the fourth and usually holds the larger machinery, such as boilers and auxiliary engines. The fourth engineer is the most junior officer and often looks after purifiers, pumps, sewage and bilge systems.
Both hold the same III/1 certificate; seniority and experience decide the rank. The fourth engineer’s responsibilities show where most engineers start.
How Does a Third Engineer Become a Second Engineer?
A third engineer becomes a second engineer after at least 12 months of approved sea service as an engineer officer. He or she then passes the exams for an STCW Regulation III/2 certificate.
On ships under 3,000 kW, Regulation III/3 applies instead. Promotion also depends on company appraisals and leadership. Many third engineers sail one or two more contracts before the company offers the second engineer post.
What Skills Does a Third Engineer Need?
A third engineer needs strong technical knowledge, problem-solving under pressure, organisation and clear communication. Leadership grows in importance as the engineer moves up the rank.
- Technical ability: operate and overhaul engines, compressors, boilers and purifiers, and read piping diagrams and mechanical drawings.
- Leadership: organise oilers and wipers, share out tasks and keep track of rest hours when senior engineers are not there.
- Problem-solving: troubleshoot faults, including a blackout at sea, with decisions that are technically sound.
- Teamwork: work and communicate safely with other crew members, often from several countries.
- Organisation: keep inventories and maintenance records current, and order spares and repair kits in time.
- Computer skills: use the PMS, reporting and requisition software.
- Reading comprehension: follow manufacturers’ manuals precisely when operating or overhauling machinery.
Is Being a Third Engineer a Hard Job?
Yes, the job is physically demanding. Third engineers lift heavy parts, work long hours on overhauls and spend much of the day in a hot, noisy engine room.
Engine-room temperatures can be high in the tropics, which makes heat stress a real risk. Rest breaks, fluids and a sensible work plan matter as much as technical skill.
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Frequently Asked Questions
What are the duties of a third engineer on a ship?
A third engineer keeps an engine-room watch and maintains assigned machinery, usually the boilers, auxiliary engines, fuel system and purifiers. The role also covers fuel transfers, bunkering preparation, logs and month-end reports.
Who does the third engineer report to?
The third engineer reports to the second engineer, who plans the engine-room work. Defects affecting seaworthiness are also reported to the chief engineer.
What certificate does a third engineer need?
A third engineer needs an STCW Regulation III/1 certificate as officer in charge of an engineering watch. It covers ships with 750 kW or more of propulsion power.
Is a third engineer an officer?
Yes. The third engineer is a licensed engine officer, usually wearing two stripes, and ranks above the fourth engineer.
What watch does a third engineer keep?
On a traditional three-watch system the third engineer often keeps the 12–4 watch. On UMS ships engineers work days and share night duty-engineer turns.
What is a third engineer called in the US?
On US-flag ships the role is usually titled Second Assistant Engineer. A new US academy graduate starts as Third Assistant Engineer, a rank closer to the international fourth engineer.
How much does a third engineer earn?
Pay depends on the flag, company and ship type. In the US, the Bureau of Labor Statistics gives a median of $109,530 a year for all ship engineers (May 2025).
How long does it take to become a third engineer?
Most engineers reach third engineer after one or more contracts as fourth engineer. The certificate itself needs approved training and at least 12 months of sea and workshop training.
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