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communication - page 3

7.3 VHF device


The radiotelephone is usually located in the cabin of a small boat. It should be:

  • securely fastened 

  • in a convenient position clear of spray and dampness

  • away from the engine and any heat source

The set is connected to the yacht's power supply with the antenna feeder cable connected. No earth is needed. A waterproof extension loudspeaker, sited close to the steering position allows the helmsman to monitor the radio without disturbing crew who may be sleeping. 

VHF is essentially a line-of-sight system, which means the radio waves don't bend very much to follow the curvature of the earth. Sometimes the signal can reflect and refract around landmasses to advantage. However, for most reliable communication, the VHF antenna must "see" the antenna of a distant station. 

The effective useful range of a VHF radio is 20-25 miles for ship to shore and 10-15 miles for ship to ship. The distance a VHF signal can reach between ship and shore installations is usually a bit further since the ground-based antenna is higher.

VHF equipment

Features on VHF radios








  1. Radio screen Channel 16 selected.

  2. On/Off control and volume

  3. Distress button - The red distress button is found on sets fitted with Digital Selective Calling (DSC). It is activated only when the vessel to which it is fitted is in distress and is always protected in some way so that it cannot be activated by accident. If pressed once and then pressed again an audible signal will be heard as it progresses through a five second countdown sequence. If it detects a DSC Distress alert, your VHF radio immediately tunes to Ch16 and sounds a loud buzzer. 

  4. Squelch control - Reception is often accompanied by a background hiss; adjusting the squelch control will reduce the noise to acceptable levels.

  5. Press to transmit switch - When the press-to-transmit switch is depresses you can speak but not listen. Release it after speaking to hear the reply. 

  6. Channel 16 over-ride - Allows Ch16 to be selected without using the alpha-numeric key pad. 


English was chosen as the international radio language over one hundred years ago.


Radio channels should never be used for "social chatter". All conversations - called "traffic" - should be about the safety or the manoeuvring of a boat so that vital distress and urgency messages are not missed. The mobile phone should be used to discuss football scores or the local restaurant's menu!

The radio regulations

The international Telecommunication Union gives the following list of "strictly forbitten transmissions" so that interference is not caused to others.

  1. The transmission of profane, indecent or obscene language.

  2. Making unnecessary transmissnions or transmitting superfluous signals.

  3. Transmissions made without identification - the boat's name must be stated every time the microphone is keyed.

  4. The broadcast of music.

  5. The transmission of false or deceptive distress, safety or identification signals.

  6. Transmissions not authorised by the skipper or person in charge of the boat.

  7. Operation of the radio by an unauthorised person Passengers or other members of the crew may make radio telephone calls under the supervision of a qualified operator. 

  8. The broadcast of messages to an unlicensed shore station. 

  9. The use of personal names or unauthorised names in lieu of the boats's name.

  10. Closing down the radio before finishing all operations resulting from a distress call.

  11. The use of frequencies or channels other than those covered by the ship's licence. 

Control of communication

Officially it is the station being called who controls communication. However, when DSC is being used it is the caller who chooses the channel. Of course, the called station may always suggest a change of channel if it thinks it necessary.

When DSC is not used it is still preferable for the caller to choose a known empty channel so that the time spent talking on Channel 16 is redused to a minimum. In all cases a Coast Station controls communication. 

Getting ready to make a routine call (without DSC)

  1. Turn the set on and adjust the squelch (if necessary). 

  2. Adjust the volume and select LOW POWER.

  3. Select Channel 16.

  4. Before trasmitting, check that other people are not using the chosen channel. If it is occupied, wait for the end of the conversation or find another channel.

  5. Hold the microphone about eight cm from the mouth then press the switch on the picrophone to transmit - do not speak until you have pressed the button. 

  6. Prepare to speak clearly and slowly at a normal conversation level. If somebody is likely to write your message down, slow down even more.

  7. Try to avoid dropping the voice at the end of a word or phrase. If you have a strong accent, try to make your pronunciation as clear as possible. 

How to call

First, you must decide how many times you are going to call the other station's name. the general rule is: 

Calling another ship station

  1. Say their name twice if they are likely to be near the radio but if the weather is bad and the wind is howling it may be prudent to call three times - the Rule states that the maximum is three times.

  2. Say your name twice or three times as necessary.

Example call on Ch16:​

Seaspray, Seaspray, this is Nafsika, Nafsika, Suggest channel zero eight. Over.

Answer: Nafsika, this is Seaspray. Switching to channel zero eight.

Both boats allow time for switching channels then Nafsika makes the first call on Ch08.

Seaspray, this Nafsika on Ch08. Over.

Answer: Nafsika, Seaspray. Pass your message. Over... 

Calling a marina

  1. Select a working channel of the marina then say their name just once as they are usually listening for calls.

  2. Say your own ship's name twice.


Zea marina this is Sailing yacht Nafsika, Nafsika. Over.

Answer: Nafsika, this is Zea marina. What can i do for you? Over.

Zea marina, Nafsika, request a berth for one night for a twelve-metre sailing yacht. Over...

Unanswered calls

If you have made a routine call to another ship station and receive no reply, check that the volume and the squelch control are set correctly and that you are tuned to an appropriate channel. turn to high power.

In any event, you must wait for at least TWO minutes before calling again. You are permitted to call 3 times at two-minute intervals after which you must wait 3 minutes before trying again. As a rule, if another boat has not answered you after two calls, he is probably not listening - do not call again. 

The phonetic alphabet

Is understood internationally and may be used when a difficult word or group of letters have to be spelt out. This phonetic alphabet is shown in photo 7.3.1. before a word is spelt, the words "I spell" should be used.


"Intend to anchor off Youghal - I spell . Yankee Oscar Uniform Golf Hotel Alfa Lime - Youghal". If a Coastguard asks for your international call sign, which is MBDD, you would transmit:

My call sign is Mike Bravo Delta Delta. 


Photo 7.3.1

Procedure words (prowords)

Prowords might be described as those the professionals use. All are designed for easy international understanding and brevity. Not included are rambling pieces of chat such as: "I am signing off this channel now but will listen for any further communication from you. Have a good day!"

The Standard Marine Navigational Vocabulary was compiled to standardise communication for navigation at sea, in harbours, estuaries and port approaches and is published in full in Merchant Shipping Notice M1252.

Shown below are the words that candidates for the SRC examination need to know.

THIS IS - From a station whose name or callsign immediately follows.

OVER - The invitation to reply. "Over and Out" is NEVER used.

REQUEST RADIO CHECK - Please tell me the strenght and clarity of my transmission.

I SAY AGAIN - I am repeating what i have just said (or a portion of it).

STATION CALLING - Used when a station receives a call which is intended for it but is uncertain of the identification of the calling station.

READ BACK - Please read back the message that i have just sent to to you.

WRONG - Reply to a message that has just been "read back" but is in error.

CORRECT - Reply to message that has been read back for check.

CORRECTION - Spoken when a mistake has been made. The correct words or group follows.

RECEIVED - Your message has been received and understood. In case of language difficulties the word ROMEO may be used.

WAIT - If a station is unable to accept traffic immediately, it will reply with the words Wait..minutes. 

I SPELL - I shall spell the next word or group.

ALL AFTER - Used after the pro-words "Say again" to request the repetition of a portion of a list or message.

ALL BEFORE - Used after the pro-words "Say again" to request the repetition of a portion of a list or message.

REPEAT - Used if any part of a message is considered important to need emphasing.


When latitude and longitude are used these shall be expresses in degrees and minutes North or South of the Equator and East or West of Greenwich.

The numerals should be spoken digit by digit.

Example: 50° 12'.4N 001° 27'.7W should be read:

Five zero degrees one two decimal four minutes north, zero zero one degrees two seven decimal seven minutes west. 


Preferably to be expressed in nautical miles or cables (tenths of a mile). Metres and kilometres may be used but the unit should always be stated.


To be expressed in knots. Without further notation meaning speed through the water


Use the 24-hour clock and indicate whether it is UTC, local time or zone time.

Garbled calls

When a station receives a call but is uncertain for whom it is intended. 

Example: ....this is Nafsika - over.

It must not reply until the call has been repeated and understood. 

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