Speaking and listening on the radio are distinct activities from normal speaking and listening, and this is particularly important to remember when speaking. Radio transmission clarity requires a shift from natural habits of speech into a more self-conscious procedure emphasizing clarity, brevity and certainty. Following the directives of pronunciation is imperative for the operator. As you can see from the expression of numbers, an initial system is in the process of being scrapped for one that is more likely to ensure accurate transmission and comprehension.

Other than following prescribed pronunciations and processes, the operator must always remain conscious of precision in pronunciation, and refrain from inserting extra sounds into his speech—even such reflexive habitual sounds as ‘ah’, ‘er’, ‘um’, etc. At the initiation of any transmission the operator should be aware of the microphone placement, so that he is not to close or too far from the microphone. In urgent situations it is common for the speaker to ‘mouth’ the microphone, blurring the sounds so that they become incomprehensible.

The main guidelines to follow are:
  • Use all prescribed words, codes and phrases
  • Speak clearly without emitting extraneous sounds
  • Establish, when there is time, a pitch that is most comprehensible, as well as the optimal distance of mouth from microphone, tempo and volume
  • Follow the established order of transmission where applicable
Most non-emergency calls follow the same pattern:
  • The identity of the station called, followed by “THIS IS + (Your identification),” followed by the word “OVER”, which always ends your portion of a conversation segment.
  • After contact has been established, whatever message you wish to transmit follows you identification and is followed by “OVER”.

Important procedural words

Before listing important words and phrases, it would perhaps be beneficial to list the priority of communications:
  1. Distress communications (highest priority)
  2. Urgency messages
  3. Safety messages
  4. Navigational directives: bearings
  5. SAR messages
  6. Meteorological messages
  7. Messages related to the UN Charter (for ships engaged by the UN)
  8. Service messages related to R/T or related to previous messages
  9. All other communications
A review of key emergency words:
Although a complete list of Standard Marine Communication Phrases (SMCP) is beyond the scope of this course, it is highly recommended that you expand your marine radio vocabulary to include the following terms, understanding their precise usage.
Note for non-native English speakers: The following terms may be just as difficult for native English speakers, for they generally have a tendency to think in terms of synonyms for the standard words.

Message marker words: question, answer, request, information, advice, instruction, warning, intention. These words are used to announce the type of message you are about to broadcast, enhancing the likelihood of rapid comprehension and response.
  • “Question: How many tugs do you require?”
  • “Answer: I require one tug.”
  • “Request: immediate tug assistance.”
  • “Information: my position is…”
  • “Advice*: maintain course…” *Advice is strongly recommended as opposed to instruction, which, though put mildly, is actually an order.
  • “Instruction: alter course to…”
  • “Warning: Gale force winds…”
  • “Intention: I intend to alter course to port…”
Each of these message marker words along with their messages require a standard response:
  • Answer:
  • Request received:
  • Information received:
  • Advice received:
  • Instruction received:
  • Warning received:
  • Intention received:
The following are words used to clarify, or ensure proper understanding during radio communication:
  • Understood:
  • Mistake…correction
  • Stay on
  • Nothing more
  • Say again (not ‘repeat’!)
  • Read back
The following list of words and phrases are commonly used and should be known and understood by all marine radio operators (they are taken from IMO SMCP recommendations):
  • Acknowledge…This means 'let me know that you have received and understood this message'
  • Affirmative…Yes, or permission granted
  • All ships in…Request that all ships in stated area listen to what follows
  • Break…I must break into transmission for urgent reasons
  • Calling…I wish to speak to…
  • Channel…change to channel_______ before proceeding
  • Confirm…My understanding is_______, please verify.
  • Correction…An error had been made, following is the correct version…
  • Go ahead…Proceed with your message
  • How do you read?...How well are you receiving me? (Do you receive me?) Answers: I read bad/poor/well/good/excellent, or 1 through 5, 5 being excellent
  • I say again…I will say again (importantly, never use the word repeat in this situation)
  • I am coming to your assistance…response to an initial distress message when applicable
  • Mayday relay…spoken words for distress relay signal
  • Message for you…I have a message for you and will read it when you let me know you are ready to receive it…(proceed, after acknowledgment, to read message)
  • Mistake…There is a mistake in your transmission. Correction:
  • Negative…No, or that is not correct, or I do not agree
  • Over…My transmission has ended and I expect a response from you
  • Out…Transmission ended and no response expected.
  • Please acknowledge…Indicate that you have received what I have just said…
  • Readback…Repeat entire message exactly as received after I have said ‘Over’…
  • Standby…I must pause briefly, please wait…
  • Seelonce*…Indicates that silence has been imposed on the frequency due to a distress situation (*also spelled Silence, but understood to have a French pronunciation)
  • Seelonce Feenee*…cancellation of distress radio silence (*also Silence Fini, French pronunciation)
  • Seelonce Mayday…transmitted from a ship in distress to indicate ‘Seelonce’ conditions
  • Stand by on VHF channel…Remain on VHF channel (“Standing by on channel…”)
  • Standing by on…I agree to keep watch on VHF channel
  • Stay on…Do not terminate conversation, I have more to say
  • Stop transmitting…stop transmitting on this channel—a higher priority transmission has begun or is about to…
  • This is…Used to identify a station…
  • VHF channel__unable…I cannot switch to channel___
  • VHF channels available…I can transmit on the following channels
  • Words Twice…either request to receive or announcement of intent to transmit each word twice due to difficulty of communication

International code of signals (ICS)

The purpose of the International Code of Signals is to provide ways and means of communication in situations related essentially to safety of navigation and persons, especially when language difficulties arise. Orignally it was a system using flags, but could also be used by other means (RT, sound, signal lamp …). Every SOLAS ship should be equipped with ICS, while for other vessels it is strongly recommended.

For examples see appendix.


Q codes are a long series of three letter abbreviations beginning with Q that were originally developed for commercial radiotelegraphic communication, but later was found very useful for radio users to communicate with people who spoke different languages. Naturally, this made the Q codes interesting to marine communication experts. However, the vast number of codes and the near impossibility of memorizing all of them has reduced the efficacy of this system of communication, though the system remains popular with radio amateurs.

A list of Q codes applicable for maritime communications can be found in many manuals such as the ITU Manual for use by the Maritime mobile and Maritime Mobile-Satelite Services. And you should know that Q codes applicable to maritime transmissions range from QOA (meaning ‘can you communicate by radiotelegraphy {500 kHz}?) to QUZ (may I resume restricted working?).
Q codes are turned into question form in radiotelephony by the addition of RQ (ROMEO QUEBEC) at the end of a transmission.

Internationally understood responses of 'yes' and 'no' are standardized in Q code correspondence to C (spoken ‘Charlie’) for 'yes', and NO (spoken ‘No’) for no. In Q code correspondence all times are to be understood as UTC unless otherwise noted. An asterisk following a Q code abbreviation means that it has a meaning similar to a signal that is part of the International Code of Signals.

A list of Q-codes is included in the appendix.
Last modified: Saturday, 25 April 2020, 7:50 PM