Fourth engineer duties and responsibilities are keeping an engine-room watch and maintaining assigned auxiliary machinery. That usually means purifiers, pumps, the sewage plant and the oily water separator. The fourth engineer (4th engineer) is the most junior engineer officer and reports to the second engineer.
This guide covers the daily duties, the watch and pollution-prevention records. It also sets out the certificates needed in four countries and the path to third engineer.
What Is a Fourth Engineer on a Ship?
A fourth engineer is the most junior licensed engineer officer on a merchant ship, ranking below the chief, second and third engineers. He or she holds an STCW Regulation III/1 certificate and usually wears one stripe.
It is the first officer job after an engine cadetship. On US-flag ships the equivalent rank is Third Assistant Engineer, and in India the certificate is called Marine Engineer Officer (MEO) Class IV.
Some fleets also carry a junior engineer or engine trainee below the fourth engineer. How the engine department fits the crew is set out in our guide to shipboard organization and ranks.
What Are the Main Duties of a Fourth Engineer?
The main duties are standing an engine-room watch, maintaining assigned auxiliary machinery, running pollution-prevention equipment and keeping its records. The fourth also assists with bunkering, drills and major overhauls. The second engineer decides the exact machinery split.
- Purifiers: operate and clean the fuel and lube oil purifiers on many ships, sharing the work with the third engineer on others.
- Pumps: maintain fuel transfer, cooling water, ballast and fire pumps as assigned in the planned maintenance system.
- Sewage: run and maintain the sewage treatment plant.
- Bilge and oily water separator: keep the bilge system and the 15 ppm separator in working order.
- Air compressors: on some ships, keep them running and serviced.
- Ballast water treatment: on some ships, operate and maintain the ballast water treatment system, which the BWM Convention requires.
- Deck machinery: on cargo ships, assist with hydraulic deck cranes and hatch cover systems during cargo work.
Machinery allocation varies by company. The third engineer’s duties usually cover the boilers, auxiliary engines and fuel system.
What Watch Does a Fourth Engineer Keep?
On a traditional three-watch system the fourth engineer often keeps the 8–12 watch, with an oiler or motorman. On watch he or she monitors machinery, takes rounds, answers alarms and logs readings.
- Check temperatures, pressures, leaks, levels and bilges on every round.
- Stand by in the engine room during manoeuvring, such as arrival, departure and canal transits.
- Call the second engineer at once if unsure, and the chief engineer for any serious failure.
How Does the Fourth Engineer Work on a UMS Ship?
Many cargo ships run unmanned machinery spaces (UMS). Engineers then work days and share night duty, with alarms extended to the duty engineer’s cabin.
A UMS ship needs a class notation from its classification society, such as ABS ACCU, DNV E0 or Lloyd’s Register UMS. SOLAS Chapter II-1 Part E sets the basic requirements for periodically unattended machinery spaces.
The duty engineer takes the evening rounds before the engine room is left unattended. Rest hours under the STCW Code still apply: at least 10 hours in any 24 and 77 in any 7 days.
How Does a Fourth Engineer Help With Fuel and Bunkering?
The fourth engineer helps prepare the fuel system, takes tank soundings and lines up valves under the second engineer. The chief engineer is in charge of bunkering and signs the bunker documents.
Daily soundings of fuel, lube oil and sludge tanks keep the remaining-on-board figures current. The full sequence is described in bunkering on ships.
What Pollution-Prevention Duties Does a Fourth Engineer Have?
A fourth engineer often runs the oily water separator, the sludge and bilge systems, and the sewage plant. These operations must meet MARPOL discharge limits and be recorded correctly.
- Oily bilge water may be discharged only through 15 ppm oil filtering equipment under MARPOL Annex I. Larger ships also need an alarm and automatic stop.
- Every bilge and sludge operation goes in the Oil Record Book Part I, signed by the officer in charge.
- Sewage discharge follows MARPOL Annex IV distance and treatment rules.
- Garbage from the engine room, such as oily rags and filters, is segregated under MARPOL Annex V.
Inspectors check these records closely, and false entries can lead to detention and prosecution of the ship’s officers.
Which Safety Duties Does a Fourth Engineer Have?
The fourth engineer takes part in drills and tests emergency machinery. Typical jobs are the lifeboat engines, the emergency generator, the emergency fire pump and engine-room fire-fighting systems.
On many ships the fourth engineer maintains the lifeboat engines with the third officer. During a fire or abandon-ship drill he or she usually joins the engine-room or emergency team.
What Happens When a Fourth Engineer Joins a Ship?
A new fourth engineer takes a handover from the officer leaving the ship. The handover covers the condition of each assigned machine, open defects, overdue jobs and the spare-parts inventory.
- Walk the assigned machinery with the outgoing engineer.
- Check the bunkering lines, bilge and sludge discharge systems.
- Review the planned maintenance system for overdue or upcoming jobs.
- Complete the ship’s safety familiarisation before standing a watch.
How Is a Fourth Engineer’s Performance Judged?
A fourth engineer is judged mainly on keeping machinery reliable and records accurate. Three measures appear in most company appraisals.
- No overdue maintenance: critical jobs in the planned maintenance system are done on time.
- Reliable machinery: purifiers, compressors and other assigned equipment run without avoidable breakdowns.
- Spare parts: stocks of gaskets, filters, bearings and repair kits are kept up and ordered in time.
What Qualifications Does a Fourth Engineer Need?
A fourth engineer needs an STCW Regulation III/1 certificate as officer in charge of an engineering watch. That usually means a marine engineering course, an engine cadetship with 12 months of sea and workshop training, and an exam.
The international rules are explained in our guide to the STCW certificate of competency. Each country issues the certificate and names the first rank differently.
| Country | First engineer officer certificate | Usual entry route | Authority |
|---|---|---|---|
| United States | Third Assistant Engineer | Maritime academy engineering degree, or 1,080 days in the engine room (720 as QMED); minimum age 19 | US Coast Guard NMC (46 CFR 11.516) |
| United Kingdom | Engineer Officer of the Watch (EOOW) | Approved cadetship with 12 months of sea and workshop training, then the MCA oral | Maritime and Coastguard Agency (MSN 1857) |
| India | Marine Engineer Officer (MEO) Class IV | B.E./B.Tech Marine Engineering, or the 1-year GME course, then sea service and the MEO Class IV exam | DG Shipping (now DGMA) |
| Philippines | Officer in Charge of an Engineering Watch (OIC-EW) | BS Marine Engineering with 12 months of onboard training, then the exam and assessment | MARINA (STCW Circulars 2018-08 and 2018-09) |
How Much Does a Fourth Engineer Earn?
A fourth engineer’s pay depends on the flag, company, ship type and any collective agreement. Gas carriers and tankers usually pay more than bulk carriers, but published figures vary widely and are rarely official.
For the US, the Bureau of Labor Statistics gives a median of $109,530 a year for all ship engineers (May 2025). Entry-level officers earn less than that median.
How Does a Fourth Engineer Become a Third Engineer?
A fourth engineer becomes a third engineer through experience and company promotion, not a new certificate. Both ranks hold the same STCW III/1 certificate, and most companies promote after one or two good contracts.
Moving on to second engineer needs at least 12 months of sea service as an engineer officer and an STCW III/2 certificate. Chief engineer is the next step after that.
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Frequently Asked Questions
What are the duties of a fourth engineer on a ship?
A fourth engineer keeps an engine-room watch and maintains auxiliary machinery such as purifiers, pumps, the sewage plant and the oily water separator. The role also covers soundings, drills and Oil Record Book entries.
Who does the fourth engineer report to?
The fourth engineer reports to the second engineer, who assigns the machinery and daily jobs. Serious failures are also reported to the chief engineer.
Is a fourth engineer an officer?
Yes. The fourth engineer is the most junior licensed engineer officer, holds an STCW III/1 certificate and usually wears one stripe.
What watch does a fourth engineer keep?
On a traditional three-watch system the fourth engineer often keeps the 8–12 watch. On UMS ships engineers work days and share night duty-engineer turns.
What is a fourth engineer called in the US?
On US-flag ships the equivalent rank is Third Assistant Engineer. It is the first licence for most US maritime academy engineering graduates.
What is a 4th class marine engineer?
In India, the Marine Engineer Officer Class IV certificate qualifies an officer to sail as fourth engineer. It is India’s version of the STCW III/1 certificate.
What is the difference between a third and fourth engineer?
The third engineer is senior and usually holds boilers, auxiliary engines and the fuel system. The fourth is junior and often looks after purifiers, pumps, sewage and bilge systems.
How long does it take to become a fourth engineer?
Most fourth engineers complete a marine engineering course and an engine cadetship with at least 12 months of sea and workshop training. In total that usually takes three to four years.
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