Bosun, Able Seafarer and Ordinary Seaman: What Is the Difference?
Three deck titles, different responsibilities. Compare supervision, practical deck work and certification without assuming that one company’s promotion ladder applies to every vessel or flag.
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An ordinary seaman, an able seafarer and a bosun can work alongside each other on deck, but their responsibilities are not interchangeable. The useful distinction is between developing experience, carrying out competent deck work and organising other people's work.
Three roles on the same deck
Ordinary seaman, or OS: often a developing deck role. Carnival's example includes maintenance, assistance with stores and arrival preparations, and assigned lookout support. An entry-level-sounding title does not guarantee that the employer accepts applicants without sea experience.
Able seafarer, often advertised as AB: a more qualified deck rating. Carnival's AB description includes lookout, hand steering, mooring assistance and supervised maintenance. The actual watch duties depend on certification, competence and assignment.
Bosun, also written boatswain: a practical supervisory role. Carnival's 2nd Bosun description includes coordinating maintenance, coaching ratings and supporting the 1st Bosun. Some vessels use one bosun; others divide responsibilities further.
These are examples, not a promise that every OS becomes an AB and then a bosun on a fixed timetable. Employer titles and formal certificates are different things.
Training matters more than the label
The UK Maritime and Coastguard Agency distinguishes watch-rating, efficient deck hand and able-seafarer requirements. Other administrations have their own application and recognition processes. Ask which certificate and endorsement the vacancy actually requires, then check with the issuing administration or approved training provider.
Do not pay for a course simply because a recruiter calls it the next step. Request the course's exact name, approving authority and explanation of how it fits your route.
For a practical interview example, describe an assigned task, the instructions you confirmed and when you asked for help. Knowing your limits is a strength in deck work. This article cannot train someone to moor a vessel, work aloft or enter a tank.
Before you accept
Ask whether the position is watchkeeping or day work, who supervises you, which equipment familiarisation is included and how sea service will be documented. Also ask about protective equipment, working-hour records and the process for raising an unsafe-task concern.
Keep the written job description beside the offer. If the two describe different ranks, resolve that before travelling.
Your next step
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Sources
- Carnival: Ordinary Seaman. Example OS duties and experience expectations
- Carnival: Able Body. Example AB deck and watchkeeping duties
- Carnival: 2nd Bosun. Example supervisory duties and variation within bosun ranks
- MCA: Able Seafarer, Rating and EDH requirements. Separate UK deck-rating certification pathways
Sources are references, not endorsements. Examples in this article are illustrative and do not describe a particular company, ship or person. Arrangements vary by employer and vessel: your own ship's instructions come first.
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