Human factors · Communications · Safety at sea
A radio may work perfectly while the message itself fails. Under pressure, attention narrows, memory becomes less reliable and ordinary conversation habits become dangerous.
Stress does not simply make people speak faster. It changes what they notice, what they remember and how they interpret incomplete information. At sea, those effects can meet noise, weak signals, unfamiliar voices and a channel shared by many users.
The radio is only one link
A successful exchange requires a chain: the sender must recognise what matters, form a clear message, transmit it intelligibly, reach the right station and receive confirmation that the meaning—not merely the sound—was understood. Stress can weaken every link.
A person dealing with flooding, fire, injury or loss of control may try to explain the whole story at once. The result is often a long transmission in which the essential facts are buried. The listener may hear many words but still lack a reliable position, the nature of the problem or the number of people at risk.
Urgency increases the need for structure precisely when structure becomes hardest to maintain.
What pressure does to a message
Under stress, people commonly experience narrowed attention. They may focus on the most visible problem and omit information that is obvious to them but invisible to the receiving station. Working memory also becomes crowded: a call sign, position, channel instruction or question can disappear almost as soon as it is heard.
Speech may accelerate, volume may rise and breathing may become irregular. None of these guarantees clarity. A louder transmission cannot repair clipped words, an overdriven microphone or a message delivered without pauses.
Expectation creates another trap. Listeners may hear what they anticipate rather than what was said—especially with similar vessel names, numbers or place names. That is why acknowledgement and read-back matter. “Received” confirms reception; repeating the critical detail helps confirm meaning.
Why standard language helps
The IMO Standard Marine Communication Phrases were developed to standardise safety-related verbal communication and reduce misunderstandings caused by language difficulties. The phrases use simplified maritime English and cover ship-to-ship, ship-to-shore and onboard situations.1
Standard wording reduces the number of choices a speaker must make. It also gives the listener a familiar pattern. Prowords, a predictable order of information and short transmissions are therefore not ceremonial habits. They are tools for reducing cognitive load.
The listener is part of the safety system
Good communication is not produced by the caller alone. A skilled receiving operator slows the exchange down without wasting time. Short, specific questions—position, nature of distress, assistance required, persons on board—turn an unstructured account into usable information.
Closed-loop communication is especially valuable: the receiver repeats a critical detail, and the sender confirms or corrects it. This is not necessary for every routine sentence, but it is powerful when a digit, direction, position or intention could change the response.
Preparation creates capacity
Familiarity cannot remove fear, but it can preserve mental space. Knowing where the radio is, how to select the correct channel, how the microphone behaves and where the vessel’s identity and position can be found reduces the number of new decisions required in an emergency.
The goal is not a perfect voice. It is a message that another person can turn into action. Clear structure, deliberate pace, accurate identification and confirmation make communication more resilient when the people using it are under the greatest pressure.
References and further reading
- International Maritime Organization. IMO Standard Marine Communication Phrases.
- IMO Assembly Resolution A.918(22). IMO SMCP, 2001.
- Maritime and Coastguard Agency. GMDSS VHF DSC procedures for small boat users, updated 2024.
