Is English legally required to work on a ship?

For officers on ships of 500 GT and above, STCW requires the ability to use English in written and oral form, including IMO Standard Marine Communication Phrases. For ratings, STCW requires the ability to understand orders and communicate on safety matters, and in practice on international ships that language is English. The ISM Code additionally requires a working language the crew understands.

Does any regulation require the Marlins test?

No. No international regulation names any commercial English test. Marlins and similar tests are industry standards adopted by employers, who set their own required scores at recruitment.

Standard Marine Communication Phrases: the IMO's standardised set of English phrases for ship-to-ship, ship-to-shore and on-board communication. They exist because miscommunication causes accidents, and they are part of STCW English requirements for watchkeeping officers.

Do you need English to work at sea? STCW requirements explained

Updated 22 August 2026

Short answer: yes, and not because of any single test. English at sea stands on three legs: international regulations, your employer's recruitment thresholds, and the simple fact that a mixed-nationality crew has one language when the alarm sounds. Here is how the pieces fit together.

What STCW actually requires

The STCW Convention sets competence standards for seafarers, and English appears in them directly:

Officers of the navigational watch on ships of 500 GT and above must have adequate knowledge of English, written and spoken, to use charts and nautical publications, understand meteorological information and messages about the ship's safety and operation, and communicate with other ships, coast stations and multilingual crews. This includes the use of IMO Standard Marine Communication Phrases.
Engineer officers must be able to use English to work with engineering publications and to perform their duties.
Ratings must be able to understand orders and make themselves understood on matters relevant to their duties, above all safety. On international ships the working language is, in practice, English.

On top of this, the ISM Code requires a working language on board that the crew actually understands, and on mixed-nationality ships that language is English almost by definition.

Why SMCP exist

Accident reports keep repeating one chapter: communication failure. The IMO answered with Standard Marine Communication Phrases, a controlled set of English phrases for the situations where misunderstanding kills: navigation, distress, fire, man overboard, pilotage, cargo. Learning SMCP is not bureaucracy; it is the same category of protection as a harness. That belief is the reason this site exists: knowledge gives safety at sea.

Where the tests come in

Here is the part that surprises many candidates: no regulation names any commercial English test. STCW says what you must be able to do; it does not say how an employer should check it. The industry filled that gap with recruitment tests, most commonly the Marlins English Language Test, and each employer sets its own required score, typically 70-80% and higher for senior and DP positions. So your legal obligation and your recruitment reality are two different bars, and the recruitment bar is usually the higher one.

What this means for you

If you are aiming at officer positions, treat English as a core professional skill, equal to navigation or engineering knowledge. It is examined at certification and again at every recruitment.
If you are a rating, strong English widens your market dramatically: it is often what separates candidates with identical documents.
Wherever you are now, measure first. Our free English check shows your level in 10 minutes, section by section.

Frequently asked questions

Is English legally required at sea?: For officers on ships of 500 GT and above, yes, explicitly under STCW, including SMCP. For ratings, STCW requires understanding orders and safety communication, which on international ships means English.
Does any law require the Marlins test?: No. Commercial tests are employer standards, not regulation. Employers set their own score thresholds.
What are SMCP?: The IMO's Standard Marine Communication Phrases: standardised English for safety-critical communication at sea.

This guide summarises requirements for information purposes and is not legal advice. Certification details depend on your flag administration: always confirm with your maritime authority or training centre.