Marine VHF radio stands as an indispensable tool for maritime communication, ensuring safety, efficiency, and connectivity on the water. This vital technology enables seafarers, from commercial shipping to recreational boating, to communicate with each other, with shore-based stations, and in times of emergency.
Understanding the intricacies of marine VHF radio, including its functionality, regulations, and best practices, is crucial for anyone venturing into maritime environments.
Introduction to Marine VHF
Operator Requirements
Radio licence information
Under the Radiocommunications Act 1992, the installation and operation of marine radio equipment aboard any Australian vessel must be authorised by a licence. In the case of marine VHF (Very High Frequency) equipment on board an Australian vessel this is authorised by a maritime ship station class licence. A copy of this class licence is available from ACMA. Radio call signs are no longer issued by ACMA for marine VHF. However existing radio call signs may still be used.
The class licence does not authorise the operation of a “home base“. Except in special cases, marine radio equipment in private residences will not be authorised by ACMA. The class licence allows for unqualified people to use VHF radios, provided they are supervised by a suitably qualified person.
Operators qualifications
As a minimum, under the above licence conditions, all operators of marine VHF equipment are required to possess the Marine Radio Operators VHF Certificate of Proficiency (MROVCP) as issued by the Office of Maritime Communications (OMC), a branch of the AMC, on behalf of ACMA.
Marine VHF
National and International systems exist to provide prompt and effective search and rescue assistance to ships in distress. By complying with the following procedures, ship station operators can ensure that these systems continue to work effectively for the benefit of all mariners.
The transmission of false or deceptive distress, urgency or safety messages is strictly forbidden. Extremely severe penalties, including imprisonment, exist under the Radiocommunications Act 1992, for any person found guilty of making such a transmission.
All radiotelephony distress, urgency and safety calls and messages should be spoken slowly and clearly. The phonetic alphabet and figure code should be used if necessary. Use of the Standard Marine Communication Phrases is recommended in the case of language difficulties.
Frequency of Marine VHF
Frequency spectrum
The International Telecommunication Union (ITU) has allocated various bands of frequencies throughout the frequency spectrum for maritime use. The frequency spectrum is divided into eight bands, of which frequencies for maritime VHF use fall between 30 to 300 megahertz (MHz).
The VHF channel plan, as described in the International Radio Regulations, shows a total of 59 VHF channels available for marine use.
- 56 channels are allocated for radiotelephone (voice communications).
- 22 of these channels operate in simplex mode (transmission and reception taking place on a single frequency).
- 34 of these channels operate in duplex mode (simultaneous transmissions and reception taking place on separate but paired frequencies).
- (Channel 70) is for DSC – Digital Selective CallingDigital Selective Calling (DSC); and
- (Channel 87B, and 88B) are exclusively for Automatic Identification Systems (AIS1 and AIS2 respectively).
For a complete list of VHF frequencies and uses, see the table below.
| Table of Transmitting Frequencies | |||||||
|---|---|---|---|---|---|---|---|
| Channel designator | Notes* | Transmitting frequencies (MHz) | Inter-ship | Port operations and ship movements | Public correspondence | ||
| Ship stations | Coast stations | Single frequency | Two frequency | ||||
| 60 | 156,025 | 160,625 | x | x | x | ||
| 01 | 156,050 | 160,650 | x | x | x | ||
| 61 | m), o) | 156,075 | 160,675 | x | x | x | |
| 02 | m), o) | 156,100 | 160,700 | x | x | x | |
| 62 | m), o) | 156,125 | 160,725 | x | x | x | |
| 03 | m), o) | 156,150 | 160,750 | x | x | x | |
| 63 | m), o) | 156,175 | 160,775 | x | x | x | |
| 04 | m), o) | 156,200 | 160,800 | x | x | x | |
| 64 | m), o) | 156,225 | 160,825 | x | x | x | |
| 05 | m), o) | 156,250 | 160,850 | x | x | x | |
| 65 | m), o) | 156,275 | 160,875 | x | x | x | |
| 06 | f) | 156,300 | x | ||||
| 66 | 156,325 | 160,925 | x | x | x | ||
| 07 | 156,350 | 160,950 | x | x | |||
| 67 | h) | 156,375 | 156,375 | x | x | ||
| 08 | 156,400 | x | |||||
| 68 | 156,425 | 156,425 | x | ||||
| 09 | i) | 156,450 | 156,450 | x | x | ||
| 69 | 156,475 | 156,475 | x | x | |||
| 10 | h) | 156,500 | 156,500 | x | x | ||
| 70 | j) | 156,525 | 156,525 | Digital selective calling for distress, safety and calling | |||
| 11 | 156,550 | 156,550 | x | ||||
| 71 | 156,575 | 156,575 | x | ||||
| 12 | 156,600 | 156,600 | x | ||||
| 72 | i) | 156,625 | x | ||||
| 13 | k) | 156,650 | 156,650 | x | x | ||
| 73 | h), i) | 156,675 | 156,675 | x | x | ||
| 14 | 156,700 | 156,725 | x | ||||
| 74 | 156,725 | 156,725 | x | ||||
| 15 | g) | 156,750 | 156,750 | x | x | ||
| 75 | n) | 156,775 | x | ||||
| 16 | 156,800 | 156,800 | DISTRESS. SAFETY AND CALLING | ||||
| 76 | n) | 156,825 | 156,875 | x | |||
| 17 | g) | 156,850 | 156,850 | x | x | ||
| 77 | 156,875 | x | |||||
| 18 | m) | 156,900 | 161,500 | x | x | x | |
| 78 | 156,925 | 161,525 | x | x | x | ||
| 19 | 156,950 | 161,550 | x | x | x | ||
| 79 | 156,975 | 161,575 | x | x | x | ||
| 20 | 157,000 | 161,600 | x | x | x | ||
| 80 | 157,025 | 161,625 | x | x | x | ||
| 21 | 157,050 | 161,650 | x | x | x | ||
| 81 | 157,075 | 161,675 | x | x | x | ||
| 22 | m) | 157,100 | 161,700 | x | x | x | |
| 82 | m), o) | 157,125 | 161,725 | x | x | x | |
| 23 | m), o) | 157,150 | 161,750 | x | x | x | |
| 83 | m), o) | 157,175 | 161,775 | x | x | x | |
| 24 | m), o) | 157,200 | 161,800 | x | x | x | |
| 84 | m), o) | 157,225 | 161,825 | x | x | x | |
| 25 | m), o) | 157,250 | 161,850 | x | x | x | |
| 85 | m), o) | 157,275 | 161,875 | x | x | x | |
| 26 | m), o) | 157,300 | 161,900 | x | x | x | |
| 86 | m), o) | 157,325 | 161,975 | x | x | x | |
| 27 | 157,350 | 161,950 | x | x | |||
| 87 | 157,375 | 157,375 | x | ||||
| 28 | 157,400 | 162,000 | x | x | |||
| 88 | h) | 157,425 | 157,425 | x | |||
| AIS 1 | i) | 161,975 | 161,975 | ||||
| AIS 2 | i) | 162,025 | 162,025 | ||||
Table notes:
a) Administrations may designate frequencies in the intership, port operations and ship movement services for use by light aircraft and helicopters to communicate with ships participating coast stations in predominantly maritime support operations. However, the use of the channels which are shared with public correspondence shall be subject to prior agreement interested and affected administrations.
b) The channels of the present Appendix, with the exception of Channels 06, 13, 15, 16, 17, 70, 75 and 76, may also be used for high-speed data facsimile transmissions, subject to special arrangement between interested and affected administrations.
c) The channels of the present Appendix, but preferably Channel 28 and with the exception of Channels 06, 13, 15, 16, 17, 70, 75 and 76, may be used for direct-printing telegraphy and data transmission, subject to special arrangement between interested and affected administrations.
d) The frequencies used in this table may also be used for radio communications on inland waterways.
e) Administrations having an urgent need to reduce local congestion may apply 12,5 kHz Channel interleaving on a non interference basis to 25 kHz channels, provided:
- Recommendation ITU-R M. 1084-2 shall be taken into account when changing to 12,5 kHz Channels;
- it shall not affect the 25 kHz Channels of the Appendix 4 maritime mobile distress and safety frequencies, especially the Channels 06, 13, 15, 16, 17, and 70, nor the technical characteristics mentioned in Recommendation ITU-R M.489-2 for those channels;
- implementation of 12,5 kHz channel interleaving and consequential national requirements shall be subject to prior agreement between the implementing administrations and administrations whose ship stations or services may be affected.
f) The frequency 156,300 MHz (Channel 06) may also be used for communication between ship stations and aircraft stations engaged in co-ordinated search and rescue operations. Ship stations shall avoid harmful interference to such communications on Channel 06 as well as to communications between aircraft stations, ice-breakers and assisted ships during ice seasons.
g) Channels 15 and 17 may also be used for on-board communications provided the effective radiated power does not exceed 1 W, and subject to the national regulations of the administration concerned when these channels are used in its territorial waters.
h) Within the European Maritime Area and in Canada, these frequencies (Channels 10, 67, 73) may also be used, if so required, by the individual administrations concerned, for communication between ship stations, aircraft stations and participating land stations engaged in co-ordinated search and rescue and anti-pollution operations in local areas.
i) The preferred first three frequencies for the purpose indicated in Note a) are 156,450 MHz (channel 09), 156,625 MHz (channel 72) and 156,675 MHz (channel 73).
j) Channel 70 is to be used exclusively for Digital Selective Calling for distress, safety and calling.
k) Channel 13 is designated for use on a worldwide basis as a navigation safety communication channel, primarily for intership navigation safety communications. It may also be used for the ship movement and port operations service subject to the national regulations of the administrations concerned.
l) These Channels (AIS 1 and AIS 2) will be used for an automatic ship identification and surveillance system capable of providing worldwide operation on high seas, unless other frequencies are designated on a regional basis for this purpose.
m) These Channels (18 and 82 to 86) may be operated as single frequency channels, subject to special arrangement between interested or affected administrations.
n) The use of these channels (75 and 76) should be restricted to navigation-related communications only and all precautions should be taken to avoid harmful interference to channel 16, e. g. by limiting the output power to 1 W or by means of geographical separation.
o) These Channels may be used to provide bands for initial testing and the possible future introduction of new technologies, subject to special arrangement between interested or affected administrations. Stations using these channels or bands for the testing and the possible future introduction of new technologies shall not cause harmful interference to, and shall not claim protection from, other stations operating in accordance with ITU Radio Regulations /Volume 1 / Chapter S11 – Frequencies / Article S5 / Frequency allocations.
DEFINITION
SIMPLEX – Transmission and reception taking place on a single frequency;
DUPLEX – Simultaneous transmission and reception taking place on separate but paired frequencies.
| Table 1. Professional fishing vessels frequencies | ||
|---|---|---|
| Carrier Frequency (Tx/Rx) & Channel No. | Communicating with | Purpose |
| 156,575 MHz (Ch 71) | Limited coast and ship stations | Calling and working |
| 156,625 MHz (Ch 72) | Ship Stations | Calling and working |
| 156,875 MHz (Ch 77) | Ship Stations | Calling and working |
| Table 2. Commercial vessel frequencies | ||
|---|---|---|
| Carrier Frequency (Tx/Rx) & Channel No. | Communicating with | Purpose |
| 156,300 MHz (Ch 6) | Ship Stations | Calling and working |
| 156,400 MHz (Ch 8) | Ship Stations | Calling and working |
| 156,625 MHz (Ch 72) | Ship Stations | Calling and working |
| 156,725 MHz (Ch 74) | Limited coast stations and ship stations | Calling and working |
| 156,925/161,525 MHz (Ch 78) | Limited coast stations | Calling and working |
| Table 3. Yachts and pleasure vessels frequencies | ||
|---|---|---|
| Carrier Frequency (Tx/Rx) & Channel No. | Communicating with | Purpose |
| 156,625 MHz (Ch 72) | Ship stations Calling and working | Calling and working |
| 156,675 MHz (Ch 73) | Limited coast and ship stations | Calling and working |
| 156,875 MHz (Ch 77) | Ship stations Calling and working | Calling and working |
| Table 4. Port operations frequencies | ||
|---|---|---|
| Carrier Frequency (Tx/Rx) & Channel No. | Communicating with | Purpose |
| 156,300 MHz (Ch 6) | Ship stations | Calling and working |
| 156,400 MHz (Ch 8) | Ship stations | Calling and working |
| 156,425 MHz (Ch 68) | Limited coast stations | Calling and working |
| 156,450 MHz (Ch 9) | Limited coast stations and ship stations | Calling and working |
| 156,500 MHz (Ch 10) | Limited coast stations and ship stations | Calling and working |
| 156,550 MHz (Ch 11) | Limited coast stations | Calling and working |
| 156,600 MHz (Ch 12) | Limited coast stations | Calling and working |
| 156,625 MHz (Ch 72) | Ship stations | Calling and working |
| 156,650 MHz (Ch 13) | Limited coast stations and ship stations | Calling and working |
| 156,700 MHz (Ch 14) | Limited coast stations | Calling and working |
| 156,975/161,575 MHz (Ch 79) | Limited coast stations | Calling and working |
| 157,000/161,600 MHz (Ch 20) | Limited coast stations | Calling and working |
| Table 5. VHF marine repeater channels | ||
|---|---|---|
| Carrier Frequency (Tx/Rx) & Channel No. | Communicating with | Purpose |
| 157,050/161,650 MHz (Ch 21) | Limited coast and ship stations via repeaters | Vessel movements, safety of vessels and persons |
| 157,100/161,700 MHz (Ch 22) | Limited coast and ship stations via repeaters | Vessel movements, safety of vessels and persons |
| 157,025/161,625 MHz (Ch 80) | Limited coast and ship stations via repeaters | Vessel movements, safety of vessels and persons |
| 157,075/161,675 MHz (Ch 81) | Limited coast and ship stations via repeaters | Vessel movements, safety of vessels and persons |
| 157,125/161,725 MHz (Ch 82) | Limited coast and ship stations via repeaters | Vessel movements, safety of vessels and persons |
NOTE. Public correspondence channels
- Ship stations may use those VHF frequencies detailed by their provider for public correspondence.
- Subject to the International Radio Regulations, when operating outside Australian territorial waters, ship stations may use any maritime mobile frequency authorised by those regulations. Details may be found in the Manual for Use by the Maritime Mobile and Maritime Mobile-Satellite Service, published by the International Telecommunication Union.
RANGE OF VHF
Due to the propagation conditions of VHF, that part of the radio wave emitted from the transmitter (surface or ground wave) only follows the curvature of the earth’s surface for a limited distance. Range of VHF is therefore considered as “short” and dependent on the combined height of the Ship’s Antennas Systems and Radio Wave Propagationtransmitting and receiving antennas.
Read also: SART – Search and Rescue Transponders – Portable VHF Transceivers
Generally speaking, the range of VHF is slightly greater than the visual line of sight of the combined antennas; the higher the antenna, the greater the range. During certain atmospheric conditions, particularly during the summer months, the ground wave may be refracted around the earth’s surface for a far greater range than would normally be expected of VHF. This phenomenon is known as “ducting” and should not be regarded as normal.
VHF Marine Radio Equipment
Principle of operation
VHF marine equipment offers a communications range between vessels of up to 20 km (10,8 nautical miles) and between vessel and shore of 50 km (27 nautical miles), and possibly significantly greater:
- a safety service provided by limited coast stations operated by marine rescue and other organisations;
- the advantages of being relatively inexpensive, of providing the highest quality signal, of suffering least from interference caused by atmospheric or ignition sources, and;
- of providing access to a radiotelephone service (not available in Australia); but
- the disadvantage of suffering blind spots behind cliffs, sand hills and heavy vegetation.
VHF marine equipment is suitable for small vessels remaining relatively close to the coast and within range of limited coast stations operating on VHF channels.
VHF marine equipment fitted with Digital Selective Calling facilities may offer a single button distress facility and automatic watch keeping.
The Major Parts of Radio Equipment
Marine radio equipment operating in the VHF band is made up of three major parts:
- the power supply;
- the transceiver; and
- the antenna or aerial.
Each part is dependent on the other. A fault in any one of the parts will not allow the equipment to function correctly.
The power to operate the radio equipment may be supplied by the vessel’s engine or from an independent battery.
The transmitter and receiver are combined into a single unit and commonly referred to as the “Transceiver“. The Digital Selective Calling (DSC) unit may be further integrated with the transceiver.
The antenna for a marine VHF transceiver should be mounted as high as possible, preferably at the top of a mast, in order to give greater range, and is described as “A short vertical whip or rod antenna”. Ultra-violet radiation will cause fibreglassed whip antennas to deteriorate after many years of service to a point where moisture can penetrate the layers of insulation. This will seriously affect radiation efficiency and replacement or re-fibreglassing will be necessary.
Transceiver controls
This section details the functions of important operator controls which may be found on marine VHF radio equipment. Not all will be found on each brand of equipment. Transceiver controls may be identified differently by individual manufacturers but will have the same purpose:
On/Off and Volume Control. Often these functions are combined into a single control. It is used to turn the equipment on or off, and to adjust the level of signals coming from the loudspeaker.
Squelch Control. This control allows the operator to stop the constant and annoying, internally generated, background noise from the receiver in the absence of an incoming signal. On VHF marine equipment, it is usually an adjustable control.
The correct setting is found by turning the control clockwise until the noise stops, but no further. If the control is adjusted beyond this point, the receiver will be desensitised and may not receive weak signals.
Channel Selector. This control is used to select the channel on which transmission or reception is required.
Dual Watch (DW). This control will be found on the majority of VHF equipment. In operation it will permit the operator to keep a listening watch on a working channel and Channel 16. This is NOT to be confused with scanning desirable or selected VHF channels.
Scan. This control may be available on some brands of marine VHF equipment. Not to be confused with the Dual Watch control. This control may offer the operator the choice of scanning all the marine VHF channels, or selected channels.
Power Selector. This control varies the power of the Transmission of Urgency and Safety Signals from a Vesseltransmitted signal. International regulations restrict the output power of Marine VHF to 25 Watts maximum. On VHF marine equipment it may be marked “25W/1W” (25 Watts or 1 Watt) or “high/low“. The use of more power than is required to communicate satisfactorily is a breach of the International Radio Regulations, may cause unnecessary interference, and drains the battery supplying the equipment at a faster rate. The correct transmitter power setting is generally referred to as “the minimum power to maintain reliable communication”.
It will be interesting: Ship’s Antennas Systems and Radio Wave Propagation
International/USA Control. This control may be found on some VHF marine equipment. It is provided by the manufacturer to permit communications with stations in the USA which do not conform to the International VHF channel plan. It is important that this control is kept in the International’ position at all times unless in the coastal waters of the USA. Some manufacturers of marine VHF supplied to Australian operators may have “International” substituted by “Aus“.
General care and maintenance
Vessel owners should be aware that, on occasions, a power supply fuse will blow when the transceiver is malfunctioning or for no apparent reason. It is recommended that a supply of fuses of the manufacturer’s recommended value be carried on board. For safe keeping spare fuses could be contained in a suitable container.
VHF Marine Repeaters
Principle of operation
VHF communication range depends mainly on the height of the antennas of the transmitting and receiving stations. By using VHF marine repeater stations, the range of ship to ship, ship to shore and shore to ship communications can be significantly increased.
VHF marine repeaters are unmanned shore installations usually located at geographically high points. They are designed to transmit and receive simultaneously and will retransmit or “repeat” all signals received. Retransmitted signals can be received by any station listening on the repeater channel.
Limited coast stations operated by marine rescue organisations routinely monitor VHF repeater channels operating in their area. Not all coastal areas of Australia are served by VHF marine repeaters.
VHF marine repeater channels
VHF marine repeaters operate in the DUPLEX mode on channels 21, 22, 80, 81 or 82. For their own safety, boat owners should ensure that they are familiar with the location and operating channel of their local repeater.
Digital Selective Calling alerts using VHF must be confined to channel 70 and will not operate through repeaters.
Use of VHF marine repeaters
In most cases VHF marine repeaters are installed and maintained by marine rescue organisations as a service to mariners and are available for use by all licensed VHF ship stations. However, in order to minimise congestion, if direct ship to ship or ship to shore communications are possible on a non-repeater channel, this must be used in preference.
Source: AI generated image
Repeater channels must not be used as “chatter channels“. Communications must be restricted to those concerning the movements of vessels and safety of vessels and persons. To discourage lengthy conversations, repeaters will incorporate an automatic time restriction of approximately thirty seconds.
If not apparent by monitoring, a ship station can gain an indication of its ability to access a repeater by momentarily depressing the microphone button. If a brief (approximately one second) burst or “tail” of noise is heard from the loudspeaker when the button is released. then the vessel is activating the repeater. If a “tail” is not heard, it is probable that the vessel is out of range of the repeater.
Operators using VHF equipment equipped with an “International” or “Aus” channel switch should note that it is essential that the switch be in the “International” or “Aus” position to access repeaters.
Stations for Marine Communications
Limited coast stations
Limited Coast Stations are stations on land established for the purpose of communicating with vessels at sea. These stations are primarily responsible for the safety of movement and operation of vessels within their local area. These stations are not licensed to handle public correspondence.
There are no fixed hours for the radio service provided by Limited Coast Stations and many do not offer a continuous service. Hours of service are determined by local requirements or, in some cases, by State Government legislation.
In the interests of safety, boat operators should familiarise themselves with services available to their area of operations. Limited Coast Stations generally fall into the category of marine rescue units, yacht clubs or fishing cooperatives.
Station identification
Transmission without identification is forbidden. All transmissions should be identified by the vessel’s name, any other identity (if available) or by other means, such as the Maritime Mobile Service Identity (MMSI).
Operating Procedures
National and International systems exist to provide prompt and effective search and rescue assistance to ships in distress. By complying with procedures in this chapter, ship station operators can ensure that these systems continue to work effectively for the benefit of all mariners.
All Distress Signals And Distress Trafficradiotelephony distress, urgency and safety calls and messages should be spoken slowly and clearly. The phonetic alphabet and figure code should be used if necessary. Use of the standard marine vocabulary is recommended in the case of language difficulties.
Authority of the master
A ship radio station and the service it provides are placed under the authority of the master, skipper, or the person responsible for the safety of the vessel.
Priority of communications
All radiotelephony communications have been prioritised as follows:
- Distress calls, messages and traffic are broadcast to all stations on distress channels.
- Urgency calls, messages and traffic may be broadcast to all stations or transmitted to an individual station on channels allocated for distress communications or on a working channel if the message is of an urgent medical request or repetition of an overdue vessel report.
- Safety calls and messages may be broadcast to all stations or transmitted to an individual station. The safety message will always be transmitted on a working channel. An acknowledgment is not expected for a safety broadcast.
- General or Routine communications will always be transmitted to an individual station on a working channel.
Radiotelephony calling & working channels
Channels allocated to ship and limited coast stations are categorised as either calling or working channels:
- calling channels are for establishing the initial contact with other stations; and
- working channels are for the exchange of messages or conducting public correspondence by radiotelephone.
Protection of channels
It is important that channels are used only for the purpose for which they have been assigned; e. g. channels authorised for calling are not used as working channels. Channels authorised for calling coast stations are not used for calling ship stations.
Secrecy of communications
Article 17 of the ITU Radio Regulations prohibits the unauthorised interception of Radio Communications not intended for the general use of the public.
Secrecy of communications does not apply to the broadcast of distress, urgency or safety traffic addressed to all stations.
Watch keeping
Whilst at sea it is a requirement for small craft to maintain a listening watch on Channel 16. Regulations and Rules for Vessels to Carry Liquefied GasCommercial vessels are currently required to maintain a continuous listening watch on Channel 16.
| Common Channel | Channels, MHz | Communication with | Purpose |
|---|---|---|---|
| Ch 77 | 156,875 | Ship stations | General or routine communications |
| Ch 73 | 156,675 | Limited coast and ship stations (Yacht & Pleasure craft) | Calling and working |
| Ch 72 | 156,625 | Limited coast and ship stations | Calling and working |
| Ch 71 | 156,575 | Limited coast and ship stations (Professional Fishing vessels) | Calling and working |
| Ch 70 | 156,525 | All stations | DSC distress, urgency, safety and routine alerting |
| Ch 67 | 156,375 | All stations | Distress, urgency and safety calling (supp. to Ch 16) |
| Ch 16 | 156,800 | All stations | International Radiotelephony distress, urgency, safety and calling channel |
| Ch 13 | 156,650 | Ship stations | Intership Maritime Safety Information. May be used by Port Authorities for vessel harbour movements communications. |
| Ch 6 | 156,300 | Ship and aircraft | Co-ordinated Search and Rescue (SAR). May be used by Port Authorities for tug to ship berthing communications |
Silence periods
The international regulations no longer require silence periods to be observed on the distress and calling frequencies. Those vessels that come under the Safety of Life at Sea regulations maintain a continuous watch on VHF DSC and a listening watch on Channel 16.
Whether or not you observe silence periods, it’s important to remain tuned in to the distress channels on your marine radio. And remember – when making a radio call, always listen first. That way, you won’t interfere with anyone else who may be transmitting.
Unnecessary communications
Transmissions should be as brief as possible. Non-essential remarks, bad language and unnecessary conversations should be avoided. It is an offence under the Radiocommunications Act 1992, to use a transmitter in a manner that may cause a reasonable person to feel threatened or harassed.
Test transmissions
Test transmissions should be made on a working channel and kept to a minimum or avoided altogether on distress, urgency, or safety channels. If, after technical maintenance, or prior to departing port, it is necessary to test the radio equipment, approval from the nearest coast or limited coast station may be required.
Log keeping
Operators should keep a record of all distress alerts and messages transmitted or received. Particulars should include the station or stations with which the messages were exchanged, the channels used and the date and times of the transmission and reception. Instead of an official logbook, an exercise book could be drawn up. (See figure below).
Phonetic alphabet and figure code
When experiencing difficulties with the exchange of radio communications, e. g. language difficulties, it may be necessary to exchange communications by the use of the Phonetic Alphabet, especially during distress communications situations. (See figure below).
| Miscellaneous | ||
|---|---|---|
| Letter to be transmitted | Code word to be used | Spoken as ** |
| R | Your message is received and understood | ROMEO |
| OVER | Invitation to reply | OVER |
| OUT | This transmission is ended | OUT |
| DECIMAL POINT | Decimal | DAY-SEE-MAL |
| FULL STOP | Stop | STOP |
| COMMA | Comma | COMMA |
| / | Oblique Stroke | OBLIQUE |
| ** Each syllable should be equally emphasised. | ||
| Figure code (A few digits and numbers have a modified pronunciation compared to general English) | ||
|---|---|---|
| Letter to be transmitted | Code word to be used | Spoken as ** |
| 0 | zero | ZEEROH |
| 1 | one | WUN |
| 2 | two | TOO |
| 3 | three | TREE |
| 4 | four | POWER |
| 5 | five | FIFE |
| 6 | six | SEKS |
| 7 | seven | SEVEN |
| 8 | eight | AIT |
| 9 | nine | NINER |
| 10 | One zero | WUNZEEROH |
| 1000 | thousand | TOUSAND |
| ** Each syllable should be equally emphasised. | ||
Control of communications
During routine communications from ship to shore and ship to ship, the station being called “controls” the communication process. In order that communications may be conducted efficiently, and with the minimum of delay, instructions issued by coast or Limited Coast Stations should be followed without delay.
- International Maritime Organization. (2017). SOLAS consolidated edition 2017: Consolidated text of the International Convention for the Safety of Life at Sea, 1974, and its Protocol of 1988: articles, annexes and certificates. London: International Maritime Organization.
- International Telecommunication Union. (2020). Radio Regulations. Geneva: International Telecommunication Union.
- International Electrotechnical Commission. (2019). IEC 61162-1:2016 Maritime navigation and radiocommunication equipment and systems – Digital interfaces – Part 1: Single talker and multiple listeners. Geneva: International Electrotechnical Commission.
- International Electrotechnical Commission. (2016). IEC 61162-2:1998 Maritime navigation and radiocommunication equipment and systems – Digital interfaces – Part 2: Single talker and multiple listeners, high-speed transmission. Geneva: International Electrotechnical Commission.
- International Electrotechnical Commission. (2016). IEC 61162-3:2008 Maritime navigation and radiocommunication equipment and systems – Digital interfaces – Part 3: Serial data instrument network. Geneva: International Electrotechnical Commission.
- International Electrotechnical Commission. (2016). IEC 61162-450:2018 Maritime navigation and radiocommunication equipment and systems – Digital interfaces – Part 450: Multiple talkers and multiple listeners – Ethernet interconnection. Geneva: International Electrotechnical Commission.
- International Maritime Organization. (2017). IAMSAR Manual, Volume III: Mobile Facilities. London: International Maritime Organization.
- International Telecommunication Union. (2020). Recommendation ITU-R M.1084-5: Interim solutions for improved efficiency in the use of the band 156-174 MHz by maritime mobile service. Geneva: International Telecommunication Union.
- International Telecommunication Union. (2020). Recommendation ITU-R M.1371-5: Technical characteristics for an automatic identification system using time-division multiple access in the VHF maritime mobile band. Geneva: International Telecommunication Union.
- International Telecommunication Union. (2020). Recommendation ITU-R M.493-15: Digital selective-calling system for use in the maritime mobile service. Geneva: International Telecommunication Union.
