Boatswain: The Bosun's Job, Rank and Career Path at Sea

The boatswain, almost always shortened to bosun, is the senior rating in a ship's deck department and the working foreman of the unlicensed deck crew. The bosun takes the chief officer's maintenance and cargo plan, turns it into a day's work for the able seafarers and ordinary seamen, allocates tools and safety equipment, then works alongside the gang doing it.

It is a supervisory job that is still a hands-on job. That combination is what makes the rank hard to fill well, and it is why a competent bosun is one of the most valued people on a merchant ship.

What a bosun actually does in a working day

The bosun runs the deck day work, which on most cargo ships means the period between the morning and afternoon watches when ratings not on the bridge are working on deck. Typical responsibilities include:

• Planned maintenance of hull and deck. Chipping, priming and painting, greasing, freeing seized fittings, renewing wastage, and keeping the paint and stores log honest so the chief officer can order against real consumption.
• Mooring stations. The bosun normally runs the forward station under an officer, handling lines, tugs and the anchor party, and owns the condition of ropes, stoppers, winches and brakes.
• Cargo gear and lifting appliances. Derricks, cranes, wires, shackles, hatch covers and their sealing arrangements, plus the associated inspection records.
• Access equipment. Rigging and inspecting the pilot ladder and accommodation ladder, safety-critical work with a poor casualty record across the industry.
• Enclosed space and hot work preparation. Ventilating, gas freeing, standing by entries, and confirming permits are in place before anyone goes in.
• Stores and rigging. Running the bosun's store, ordering consumables, and keeping wires, ropes and lifting tackle certified and in date.

Where the bosun sits in the deck department

The deck department runs officers on one side and ratings on the other. The master sits above the chief officer, who has the second and third officers below him for watchkeeping. On the ratings side the order is ordinary seaman at entry, then able seafarer, then bosun at the top. Some ships in the offshore and cruise trades add a bosun's mate or lead seaman between AB and bosun.

The reporting line runs from the bosun to the chief officer, and the bosun is the translation layer between the two halves of the department. Officers set what needs doing and by when; the bosun decides who does it, in what order, with what gear, and pushes back on what is not realistic. On a ship where that relationship works, deck maintenance stays ahead of the survey cycle.

Where it does not, the chief officer ends up supervising individual ratings directly and nothing gets planned.

The certificates behind the job

There is no STCW certificate called boatswain. The rank is a company appointment, and the qualification underpinning it is the able seafarer deck certificate under STCW Regulation II/5, held on top of rating forming part of a navigational watch under Regulation II/4.

Routes differ by flag state but the shape is consistent:

• United Kingdom. The MCA requires the navigational watch rating certificate first, then 18 months of deck sea service holding it, reduced to 12 months for candidates following an approved education and training programme, plus proficiency in survival craft and rescue boats and demonstrated competence against STCW Code Table A-II/5.
• United States. The Able Seafarer-Deck endorsement is set out in 46 CFR 12.603, layered on the domestic able seaman ratings and the Merchant Mariner Credential.
• Every flag. Basic safety training under STCW Regulation VI/1 is the entry gate, and most owners add ship-type specific training such as tanker familiarization or crane operation.

Because the rank itself is not certificated, promotion is a matter of company assessment: years of AB service, appraisal reports, and demonstrated ability to lead a mixed-nationality gang safely.

How seafarers reach the rank

The normal path is ordinary seaman to able seafarer to bosun, with several years at AB before the step up. A realistic timeline from first sea time to bosun is often eight to twelve years, longer on ships with low crew turnover. Fleet size matters more than most candidates expect: a large owner with many similar ships promotes on a predictable cycle, while a small operator with three vessels may have no vacancy for years.

The rank is also a genuine junction. Some bosuns stay in the role for a whole career, and on well-run ships that is a respected professional choice. Others use it as a base to convert to officer status through a rating-to-officer scheme, which typically requires academic study plus structured sea time toward an officer of the watch certificate.

Anyone intending that move should start collecting the required watchkeeping service and academic prerequisites before taking the bosun's job, because bosun work is day work and generates little bridge watchkeeping time.

What separates a good bosun from an adequate one

Three things, consistently. The first is planning a day's work that can actually be finished with the people and weather available, rather than starting five jobs and completing none. The second is safety discipline that holds when the schedule is tight, particularly on enclosed space entry, working aloft and mooring under tension.

The third is teaching: a bosun who trains the ordinary seamen properly produces the next generation of ABs, and that is the part of the job no certificate measures.

Seafarers planning the step from AB to bosun should check their flag state's able seafarer deck requirements first, then ask the crewing department for the appraisal criteria it actually uses. More on ratings and officer progression is in the Marine Insight 360 Merchant Navy Careers section.

Sources and further reading

• 46 CFR 12.603 Requirements to qualify for an STCW endorsement as Able Seafarer-Deck
• MCA Merchant Shipping Notice MSN 1862 (M)
• Apply for navigational and engine room ratings certificates (GOV.UK)

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