Effective communication is paramount within any industry, and the maritime sector is no exception. The safe and efficient movement of goods and personnel across international waters hinges upon a robust and standardized communication infrastructure.
This article provides an overview of marine communications, exploring the established protocols, emerging technologies, and their significance for global trade and maritime safety.
Duplex and Simplex Modes of R/T Operation
The majority of radiotelephone public correspondence and commercial radio traffic is operated on a duplex basis using paired working frequencies, i. e., transmission and reception are simultaneous, using two different frequencies so that it is just like an ordinary phone call. Simplex operation is used in ship-to-ship communication using one frequency; each person needs to say “over” and release the “press-to-talk” button before they can receive.
General Procedures
Calls to coast stations should be made on the appropriate working channel whenever possible. At other times, 2182 kHz (MF) or channel 16 (VHF) should be used. On HF, the paired calling frequency should be used. The ITU List of Coast Stations should be consulted for further details.
All ships making international voyages in Region 1 should be able to use the ship-to-shore working frequency 2045 kHz and the intership frequency. However, these frequencies shall not be used for working between stations of the same nationality. Instead, the nationality authorized frequencies should be used. In regions 2 and 3, ships making international voyages should be able to use the intership frequencies 2635 kHz and 2638 kHz.
When transmitting certain expressions, unusual name and words, figures or abbreviations, the International Phonetic Alphabet should be use. This is shown in Table 1.
Table 1. International Phonetic Alphabet and Figure Code | ||
---|---|---|
Code word | Spoken as | |
A | Alpha | AL FAH |
B | Bravo | BRAH VOH |
C | Charlie | CHAR LEE or SHAR LEE |
D | Delta | DELL TAH |
E | Echo | ECH OH |
F | Foxtrot | FOKS TROT |
G | Golf | GOLF |
H | Hotel | HOH TELL |
I | India | IN DEE AH |
J | Juliet | JEW LEE ETT |
K | Kilo | KEY LOO |
L | Lima | LEE MAH |
M | Mike | MIKE |
N | November | NO VEM BER |
O | Oscar | OSS CAR |
P | Papa | PAH PAH |
Q | Quebec | KEH BECK |
R | Romeo | ROW ME OH |
S | Sierra | SEE AIR AH |
T | Tango | TANG GO |
U | Uniform | YOU NEE FORM or OO NEE FORM |
V | Victor | VIK TAH |
W | Whiskey | WISS KEY |
X | X-Ray | ECKS RAY |
Y | Yankee | YANG KEY |
Z | Zulu | ZOO LOO |
0 | Nadazero | NAH-DAH-ZAY-ROH |
1 | Unaone | OO-NAH-WUN |
2 | Bissotwo | BEES-SOH-TWO |
3 | Terathree | TAY-RAH-TREE |
4 | Kartefour | KAR-TAY-FOWER |
5 | Pantative | PAN-TAH-FIVE |
6 | Soxisix | SOK-SEE-SIX |
7 | Setteseven | SAY-TAY-SEVEN |
8 | Oktoeight | OK-TOH-AIT |
9 | Novenine | NO-VAY-NINER |
Decimal point | Decimal | DAY-SEE-MAL |
Full stop | Stop | STOP |
In practice, difficult names or words should be spoken and then spelt phonetically and then spoken again. All figures should be repeated, e. g., “eighteen miles, I say again 18 (one eight) miles”.
Speak slowly and clearly at all times. In case of communication/language difficulties, refer to IMO Standard Marine Communication Phrases.
The Q-code abbreviations are often employed by coast stations, ship stations and other types of station to aid communications. The full list of Q-Codes used in Maritime Mobile and Maritime Mobile-Satellite Services.
The Q-Code abbreviations, plus complementary information, are put in the form of a question when followed by the signal RQ (spoken as “ROMEO QUEBEC”). Some abbreviations may be given an affirmative or negative sense by adding the signals C (positive) or NO (negative) (spoken as “CHARLIE” or “NO”).
Many of the Q-Codes for the maritime mobile service have meanings similar to signals appearing in the Code of Signals (INTERCO).
R/T Call & Reply Frequencies
Internationally, 2182 kHz and VHF channel 16 are used for call and reply (calls being less than 1 minute), and by coast stations to announce traffic lists, weather bulletins, etc. For information on communications with the various coast stations, consult the ITU List of Coast Stations. Radiotelephone operation at HF and VHF is also subject to the channel plans established in Appendices 16 and 18, respectively, of the ITU Radio Regulations (see the ITU Manual for Use bye the Maritime Mobile and Maritime Mobile Satellite-Services).
The HF frequencies generally authorised for ship stations to call coast stations in the duplex (i. e., paired-frequency) mode of operation are:
- 4125*kHz;
- 6215*kHz;
- 8255*kHz;
- 12290*kHz;
- 16420*kHz;
- 18795*kHz;
- 22060*kHz;
- 25097*kHz.
The frequencies 4125 kHz, 6215 kHz, 12290 kHz and 16420 kHz are also designated as simplex mode radio-telephone distress and safety traffic frequencies (see article R/T Distress Calls, Mayday Procedures & Terrestrial Communications“NON-DSC Terrestrial Distress Communications”). Use of these frequencies for other purposes is therefore allowed only on the condition that harmful interference to distress, urgency and safety communications shall not occur.
The frequencies 4125 kHz and 6215 kHz may in addition be used for and reply purposes by coast and ship stations on a simplex basis provided that the power does not exceed 1 kW. In addition, the frequency 4125 kHz is also authorised for common use in the United States by coast stations and ship stations for radiotelephone communications on a simplex basis with the power limit of 1 kW.
Calling Procedures
Once the chosen frequency is established, the ship station operator should ensure that proceeding with the call is not likely to cause interference to transmissions already in progress. If, by chance, interference is caused then the transmission must cease as request. The station making the request should indicate the time needed to complete its traffic.
Traffic Lists
For ship to shore communications it is the ship which usually establishes communication. Coast stations with traffic for ships transmit their call in the form of a traffic list which consists of the names and call signs, in alphabetical order, of the ships for which they have traffic on hand.
Traffic lists are sent at fixed times. For this reason, ship should monitor local stations on MF or VHF and/or HF according to the information given in the ITU List of Coast Stations and relevant national publications.
If, after the name or call sign, the Q-Code QTC is sent, this indicate that the coast station has a telegram for the ship. Similarly, the Q-Code QTJ indicates that there is a telephone call for the ship.
In both cases the ship waits the end of the traffic list and then call the coast station and asks for its traffic.
Working Procedures
When making a call to a coast station on 2182 kHz the ship station operator should indicate the reason for the call and the intended working channel for the subsequent traffic, e. g.,
THIS IS
MUNDOGAS ATLANTIC (up to 3 times)
CALL SIGN LIMA ECHO ECHO NOVEMBER
I HAVE A TR FOR YOU ON CHANNEL 23
OVER
When calling on a VHF working channel, the ship should indicate which channel it is calling on.
If the station being called does not reply to a call sent three times at 2 minutes intervals, the ship should stop calling for a further period of 3 minutes.
When reply to a call, the coast station may ask the ship to go immediately to a working frequency, in which case the ship should then re-establish contact with the coast station. If the ship is given a turn number, the ship should go to the working frequency and wait for the coast station to call. Once contact is established, names or call signs need only be used once.
When a called station is unable to accept traffic immediately, it may indicate the waiting time, with a reason if the delay exceeds 10 minutes.
When a station receives a call without being certain for which the call is intended, it shall not reply until the call has been repeated. Alternatively, if the call is intended for it but the called station is uncertain who is calling, it shall replay immediately, asking for a repetition , e. g.,
PLEASE REPEAT YOUR CALL
OVER
During communications between ships and coast stations, the coast station controls the working. In communications between ships, the called ship station controls the working.
Ships stations whose operation is not continuos should not close before:
- Finishing all operations relating to distress, urgency or safety.
- Receiving or transmitting, as far as is practicable, all traffic known to be available.
When arriving in port and intending to close down, ship stations should so advise the local station.
On-board Communications
Normally conducted on VHF channels 15 or 17; or in UHV in the bands between 450 and 470 MHz. Transmitter power output is limited to 1 W on VHF; 2 W on UHF.
Call should take the form of the following examples.
From the Controlling Station (Bridge):
THIS IS
ATLANTIC CONTROL (×3)
From the Sub Station
THIS IS
ATLANTIC ALPHA (×3)
Pilot Services
A ship calling a pilot service should use, in order of preference:
- A VHF channel (usually a working channel);
- An MF R/T working frequency;
- 2182 KHz to determine working frequencies.
Communications in the Port Operations Service are restricted to those relating to the safe movements of ships, operational handling and, in an emergency, the safety of persons.
Specific details of pilot and port operations services and their frequencies are available in the ITU List of Coast Stations and other publications produced by national Administrations and service providers.
R/T Commercial Working(1.25)
An exercise in commercial working which includes a simulated distress situation is recommended for the GMDSS examination.
The following section gives an example exercise where the examiner will take the part of both the vessel in distress and the local coast station. The candidates will each assume they are on a different ship in the vicinity on the incident and must respond accordingly whilst at the same time keeping a log.
The practice working described includes more than learning about distress operations. Candidates need to be able to send a transit report (TR), make R/T link call, receive a traffic list, receive a weather bulletin, etc.
Operational Watchkeeping Procedures
Commercial working exercise should allow the candidate to gain experience in the complete sequence of operations involved in sending a TR, making link call, calling the coast station on 2182 MHz or a VHF channel with call details and the intended working channel or frequencies, etc.
Commercial Working Exercise
THIS IS
MUNDOGAS ATLANTIC (up to 3 times)
CALL SIGN LIMA ECHO ECHO NOVEMBER
I HAVE A TR AND A LINK CALL FOR YOU CHANNEL 16
PLEASE
OVER
The coast station would then reply:
MUNDOGAS ATLANTIC
THIS IS SINGAPORE RADIO
ROGER
CHANGE THE CHANNEL 27
OVER
Or:
MUNDOGAS ATLANTIC
THIS IS SINGAPORE RADIO
ROGER
CHANGE THE CHANNEL 27
STANDBY YOU ARE TURN NUMBERTWO
OVER
The reply would be:
- ROGER GOING UP (now change to the working channel);
When on channel 27, either call the coast station
[(a) above]
THIS IS
MUNDOGAS ATLANTIC (up to 3 times)
How do you read me
OVER
Or [(b) above], stand by until Singapore Radio calls again.
When the coast station asks for the TR, reply:
THIS IS MUNDOGAS ATLANTIC
MY TR BEGINS,
CALL SIGN LIMA ECHO ECHO NOVEMBER
I AM IN POSITION
BOUND FOR
END OF MY TR,
OVER
The coast station then acknowledges receipt of the TR and, if a link call has been request, will ask for the telephone number.
Then reply:
THIS IS MUNDOGAS ATLANTIC
MY LINK CALL NUMBER IS…,
I SAY AGAIN…
MY ACCOUNTING CODE IS (….)
OVER
The coast station may then give instructions to STANDBY while the call is connected and will then reply that the telephone call has been connected, read back the number (N. B.; the telephone number should be verified before completing the connection), and give the instruction GO AHEAD.
The reply then is:
ROGER GOING AHEAD (The call now takes place).
When the call is completed, inform the coast station so:
THIS IS MUNDOGAS ATLANTIC
THAT IS THE END OF MY LINK CALL,
OVER
The coast station then REPLIES, giving details of the call duration, which should be confirmed before signing off, i. e.
THIS IS MUNDOGAS ATLANTIC
I AGREE 3 MINUTES
I HAVE NO FURTHER TRAFFIC, THANKYOU,
OUT
The call details should then be recorded (the radio log may be used for the exercise, although in practice computer systems are often used to record details of chargeable calls).
At some stage of the exercise the coast station can announce the traffic list on channel 16, e. g.:
THIS IS SINGAPORE RADIO
LISTEN FOR MY TRAFFIC LIST ON CHANNEL 24
STANDBY
Then change on to the broadcast frequency, receive the list and the information (again, the log can be used for the purposes of the exercise).