Since man took to the sea, the need to communicate easily between ships has been vital. Did you know what approximately 80% of the world’s trade is done by sea? Whether to convey information about hazards or to inform a shore of your arrival, sharing messages helps to minimise injuries for all. According to a report published by the Swedish Club in 2015, poor communication was recorded as the leading culprit for maritime accidents. Therefore, it’s important that information is conveyed clearly, for the health and wellbeing of those on board. This guide will look into communication at sea and how technology has advanced to improve these systems.

The challenges of communication at sea

Unlike generic, on-shore professions, working onboard a vessel of any sort presents unique challenges when it comes to passing information. Largely, this is due to ships spending the vast majority of their time out of normal terrestrial network ranges. This inhibits the ability to communicate between ships in a traditional manner, leading to broken messages or lost information. Other challenges faced include the variety of native languages spoken and lack of face-to-face interactions for better interpretation. There are a set of standardised phrases, called the IMO Standard Marine Communication Phrases (SMCP), which were developed to ensure important safety-related information can be conveyed across language barriers to minimise the rate of misunderstanding. Regardless of this, technology continues to develop in order to combat many of the other issues that seafarers face on an everyday basis and during an emergency.

A brief history of communication at sea

The technology that supports communication onboard has continued to evolve and improve throughout the years. In the 1790’s, Claude Chappe, a French inventor, developed the semaphore communication method. It involved the use of two red and yellow flags that were placed in specific positions to convey letters or numbers to form a message. By the 1800’s, this had been adopted into the marine industry as a fast and easy way to communicate between ships.

Then, in 1872, Samuel Finley Breese Morse invented a communication system that encodes messages through a series of dots and dashes (also known as dits or dahs). This was taken on by the marine industry due to its long-reaching capabilities and speed. Specifically, during WW2, sailors relied on morse code to enable naval warships to share critical information. Over time and by the late 19th century, marine communication changed once again, morphing into Marine VHF Radio. This worldwide system of two-way radio communication is generally used for emergency situations at sea, allowing you to summon the Coastguard or other vessels of a situation. When improving safety, Digital Selective Calling (DSC) was also invented as a core part of the Global Maritime Distress Safety System.

How do we communicate at sea today?

Nowadays, the way in which we communicate at sea has advanced in line with existing technology. The majority of vessels will rely heavily on satellite systems as opposed to terrestrial alternatives. This is due to the speed at which messages can be sent and the distances they can travel. In general, there are two parties that provide marine communication services – namely INMARSAT (two-way communication) and COSPAS – SARSAT (emergency services).

When it comes to maintaining safety while at sea, the Global Maritime Distress Safety System is an internationally accepted set of standards and communication protocols that make it easier to rescue distressed ships. The requirements for different systems depends on the type of vessel and its geographical division within the four designated groupings – A1, A2, A3 and A4. All of these systems are put in place to standardise communication between countries, limiting miscommunication and the risk of serious accidents.

Communication technology found onboard

For complete and appropriate communication while at sea, standard SOLAS-compliant vessels will be fitted with a minimum level of appropriate technology. This will include:

  • VHF and DSC – for distress signals and communication.
  • MF (Medium Wave Frequency) transceiver and DSC – for general alerts and communication within an 800-miles radius.
  • HF (High Frequency) Transmitter and DSC – used for worldwide distress signals.
  • EPIRB (Emergency Position Indicating Radio Beacon) – uses LEO satellites for distress location fixing and to identify the vessel.
  • SART (Search and Rescue Radar Transponder) – for accurate location pinpointing from distress alerts.
  • Navtex – for alerts, weather updates and maritime safety reports.
  • Satcom C – for distress alerts and maritime safeties reports.

The list is not exhaustive but details much of the technology that exists at sea.

Tips for improving communication on board

It’s not just the communication between vessels and ashore that holds significance when at sea. One must consider the viability of communication on board too, in order to ensure the ship is able to arrive at its destination with minimal issues or delays.

Short messaging

When at sea, you’re up against a number of distracting factors – none less than noise pollution and distance from other crew members. Keep all messages short, concise and to the point. Use previously agreed-on phrases to reduce the chance of confusion or miscommunication. And make sure to pronounce each word clearly before waiting for a response.


There should be an agreed-upon statement or word used when a message has been heard and understood. When passing on communications, you should listen for this confirmation before proceeding.


If you do not hear the confirmation word/phrase, repeat the message clearly once more. Much of the information used to keep sailors safe while at sea needs to be shared accurately to minimise the risk of accidents. Make sure the recipient has heard you clearly and has the tools needed to proceed with the job at hand.

Marine Electronics and Safety at Pinpoint Electronics

Understanding the importance of clear communication for the maritime industry is something we, here at Pinpoint Electronics, have been doing for many years. By working with some of the most recognised and innovative names in the market, we are able to bring you the highest quality navigational, safety and communication equipment for your vessel.

Understanding the scope of communication at sea is complex and requires a clear comprehension of the world’s standards and requirements. If you would like to discuss the existing equipment onboard or have an individual request, get in contact today at or via (+44) 1392 339159.