The bosun rank is the most senior deck rating on a merchant ship. A bosun, or boatswain, ranks above the able seafarers and ordinary seamen, below every deck officer, and reports to the chief officer.
This guide explains where the bosun sits in the crew and what the word means. It then covers daily duties, the certificate and sea time needed, and pay. It is written for seafarers, cadets and anyone weighing a deck career.
What Rank Is a Bosun on a Ship?
A bosun is the highest-ranking rating in the deck department. The bosun is not an officer: the bosun leads the able seafarers (ABs) and ordinary seamen (OSs) and takes orders from the chief officer.
| Deck rank | Officer or rating | Reports to | STCW certificate |
|---|---|---|---|
| Master (captain) | Officer | Shipowner or manager | II/2 Master |
| Chief officer | Officer | Master | II/2 Chief Mate |
| Second and third officers | Officers | Chief officer | II/1 Officer of the watch |
| Bosun | Senior rating | Chief officer | II/5 Able Seafarer Deck |
| Able seafarer (AB) | Rating | Bosun; officer of the watch on watch | II/5 Able Seafarer Deck |
| Ordinary seaman (OS) | Rating | Bosun | II/4 Rating forming part of a navigational watch |
Deck cadets are officer trainees, so they sit outside the ratings’ chain. On deck, though, a cadet does day work under the bosun’s direction. The full structure, including the engine and catering departments, is in our guide to shipboard organization and ranks.
Is a Bosun a High Rank?
Among ratings, yes: bosun is the top deck job a rating can hold. It usually takes several years as an AB to reach it, and the bosun runs the whole deck crew day to day.
Compared with officers, the bosun ranks below even the third officer. Many bosuns stay in the role for a career; others study for an officer’s certificate and move up.
What Does Bosun Mean?
Bosun is the phonetic spelling of boatswain, the old name for the seaman in charge of a ship’s boats, rigging and deck crew. Both words mean the same job and are pronounced “BOH-sun”.
The word goes back to late Old English batswegen: bat meaning boat and swain meaning a young attendant. It is recorded as a minor ship’s officer from the mid-15th century, and the spelling “bosun” from 1840, according to the Online Etymology Dictionary.
Is There a Difference Between Bosun and Boatswain?
No. Boatswain is the formal spelling and bosun the everyday one; dictionaries also list bos’n and bo’sun. “Boson” is a common misspelling, and so is “boswain”.
Crew lists, contracts and wage scales usually write “bosun”. Older regulations, naval titles and some flag-state documents still use “boatswain”.
What Does a Bosun Do on a Ship?
A bosun runs the deck crew’s daily work. The bosun turns the chief officer’s plan into jobs for the ABs and OSs and supervises maintenance. The bosun also leads mooring work forward and looks after deck stores.
- Plans and assigns work: agrees the day’s jobs with the chief officer, then sets each rating’s tasks.
- Supervises maintenance: chipping, painting, greasing, wire renewal and upkeep of deck machinery.
- Leads mooring and anchoring: works the windlass and mooring winches forward under an officer.
- Runs deck stores: the bosun’s store, paint locker, ropes, wires and tools.
- Keeps the crew safe: checks permits, PPE and working practice on every deck job.
- Trains: teaches OSs and deck cadets seamanship, rigging and safe work.
On most cargo ships the bosun is a day worker, not a watchkeeper. The day usually starts with a short meeting with the chief officer. Port calls, mooring and cargo work add extra hours.
How Does the Bosun Manage Deck Maintenance?
Salt water corrodes steel and machinery constantly, so maintenance never stops. The bosun inspects the open decks and superstructure, finds rust and damage early, and plans the repair with the chief officer.
The work covers deck plating, hatch coamings, railings, cargo gear and deck machinery such as winches, windlasses and cranes. Ratings clean, chip, prime and paint, and the bosun checks the quality and finish.
Most of these jobs sit in the ship’s planned maintenance system, which the company sets up to meet section 10 of the ISM Code. The bosun’s records feed the chief officer’s maintenance reports and the company’s inspections.
What Is the Bosun’s Role in Mooring and Anchoring?
Mooring and anchoring are critical operations: one mistake can injure crew, damage the ship or pollute the sea. The bosun usually works the forward station with ABs, under the chief officer or another officer.
Forward, the bosun runs the windlass and mooring winches, handles lines and watches the snap-back zones. The bosun also maintains the anchors, the anchor chain and its stoppers, and reports how many shackles are out during anchoring.
Rigging the pilot ladder is another critical job. Under SOLAS Chapter V Regulation 23, a responsible officer supervises rigging and pilot boarding; the bosun and ABs usually rig the ladder.
What Safety Duties Does a Bosun Have?
The bosun makes sure deck work is done safely. That means the right permit, PPE and supervision for jobs such as working aloft, hot work or entering tanks and holds.
- Arranges the work permits for hot work, work aloft and enclosed space entry with the responsible officer.
- Helps the third officer maintain lifeboats, liferafts, the embarkation ladder and firefighting gear.
- Leads deck parties in fire and abandon-ship drills, often in a fire or boat team.
- Gives short safety briefings before risky jobs and stops work that is unsafe.
What Skills Does a Good Bosun Need?
A good bosun combines practical seamanship with leadership. The job needs hands-on skill with ropes, wires, paint and deck machinery, and the ability to run a small, often multinational team.
- Leadership: assigns work fairly, keeps standards high and keeps the crew calm and focused when things go wrong.
- Communication: gives clear orders on mixed-nationality crews, and reports problems to officers early.
- Problem solving: handles breakdowns, injuries and changes of plan during a job.
- Mechanical skill: maintains winches, hydraulics and deck equipment, and works with the engineers on repairs.
- Seamanship: splicing, knots, rigging, safe line handling and weather awareness.
Most of these are built over years on deck. They are covered in more depth in our guide to essential seamanship skills.
What Certificate Does a Bosun Need?
A bosun normally holds the STCW Able Seafarer Deck certificate under Regulation II/5. There is no separate bosun certificate: the company appoints an experienced AB to the role.
Requirements vary by country. In the UK, for example, the MCA application for Able Seafarer Deck asks for:
- A minimum age of 18.
- A Navigational Watch Rating certificate (STCW II/4).
- 18 months of deck sea service while holding it, or 12 months with an approved Maritime Studies Qualification.
- STCW basic training, survival craft and rescue boats, and an approved Efficient Deck Hand course.
- An ENG1 medical that does not restrict lookout duties.
In the US, the equivalent is the Able Seafarer endorsement under 46 CFR 12.401, which also requires age 18, a medical and a drug test. How STCW ratings certificates fit together is explained in our guide to the STCW certificate.
How Do You Become a Bosun?
The usual path is ordinary seaman, then able seafarer, then bosun. Bosun is not an entry-level job. It comes after years as a rating in the navigational watch and on deck day work.
- Ordinary seaman: entry level, from 16 under the MLC, with STCW basic training and a II/4 watch rating certificate.
- Able seafarer: from 18, after the sea service above and the II/5 certificate.
- Bosun: appointed by the company once an AB shows the skill and leadership to run the deck crew.
- Officer (optional): some bosuns study for an STCW II/1 officer of the watch certificate and move to the bridge.
Minimum ages and medical standards by country are in our guide to merchant navy age limits and health requirements.
How Much Does a Bosun Earn?
Under the ITF Uniform TCC agreement for 2026, a bosun’s basic wage is US$1,031 a month and total monthly pay is US$2,164. That is a floor for ships under ITF agreements; many companies pay more.
| Benchmark | Bosun | Able seafarer | Source and date |
|---|---|---|---|
| ITF Uniform TCC, basic wage | US$1,031/month | US$923/month | ITF Uniform TCC CBA, from 1 Jan 2026 |
| ITF Uniform TCC, total monthly pay | US$2,164/month | US$1,950/month | Same; includes guaranteed overtime, leave pay and allowances |
| ILO minimum basic wage | Not set for bosuns | US$690/month | ILO Subcommittee on Wages of Seafarers, from 1 Jan 2026 |
| US median pay, sailors and marine oilers | $51,520/year (bosuns and ABs combined) | US Bureau of Labor Statistics, May 2025 | |
Actual pay depends on ship type, company, flag, nationality and experience. Tankers, gas carriers and offshore vessels usually pay more than the ITF floor.
Pay is earned per contract month, not as a yearly salary. Whether it is taxed depends on the seafarer’s country of tax residence, not on the ship. Free food and accommodation on board add to its real value.
The title is shared, but the job differs. A navy boatswain’s mate is an enlisted rating in a military rank structure. A yacht bosun is a senior deckhand on a private or charter yacht.
- US Navy Boatswain’s Mate (BM): supervises deck crews in cleaning, painting and maintenance, runs small boats, and handles replenishment at sea. It is an enlisted rating, not a merchant certificate.
- Yacht bosun: leads the deck team, keeps the exterior finished to a high standard, and runs the tenders and water toys. Many hold an RYA Powerboat Level 2 and are working towards Yachtmaster.
- Merchant ship bosun: an STCW II/5 rating leading the deck crew on a trading ship, as described above.
For life on board beyond the deck, see what working on a merchant vessel is like.
Related Topics
- Deck cadet duties and responsibilities
- Duties of a third engineer
- How many crew members modern ships need
Frequently Asked Questions
What rank is a bosun on a ship?
The bosun is the most senior rating in the deck department. The bosun leads the able seafarers and ordinary seamen and reports to the chief officer.
Is a bosun an officer?
No. A bosun is a rating, not an officer, and ranks below the third officer. Older dictionaries call the boatswain a petty officer, but on merchant ships the role is the senior deck rating.
Is bosun a high rank?
It is the highest deck rank a rating can hold, usually reached after several years as an able seafarer. All deck officers still rank above the bosun.
What is the difference between a bosun and a boatswain?
There is none. Bosun is the phonetic spelling of boatswain, and both are pronounced “BOH-sun”. Bos’n and bo’sun are other accepted spellings.
Who does the bosun report to?
The bosun reports to the chief officer, who heads the deck department. During mooring or anchoring, the bosun works under the officer in charge of that station.
What certificate does a bosun need?
A bosun normally holds the STCW Able Seafarer Deck certificate under Regulation II/5. There is no separate bosun certificate; the company appoints an experienced AB.
How much does a bosun earn?
Under the ITF Uniform TCC agreement for 2026, a bosun’s basic wage is US$1,031 a month and total pay US$2,164 a month. Many companies, especially on tankers and gas carriers, pay more.
A bosun can steer under an officer’s orders, like any able seafarer. A bosun cannot take charge of a navigational watch without an STCW officer of the watch certificate.
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