VHF Procedures

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WorldVHF_RadioVHF_ProceduresVHF Procedures


Maritime radiotelephone apparatus should be operated only by or under the supervision of operators in possession of at least a Restricted Radiotelephone Operators Certificate and an Authority to Operate a Marine VHF Radio.


The interception of communications other than those which the station is licensed to receive, is forbidden. If such communications are received involuntarily they may not be reproduced in writing, communicated to other persons or used for any purposes whatsoever.

Radio Logbook

Every shipstation operating on Maritime radio frequencies should keep a radio log (diary of the radio service) which should be kept on board available for inspection by Radio Inspectors appointed by the Postmaster General. Each sheet of the log should be numbered and dated and when completed, the logbook or copies of the logsheets should be handed in or posted to the nearest Radio Inspector. The times of all entries made in the log should be in Greenwich Mean Time (GMT) and the following entries should be made:

  • Name, address and qualifications of the radio operator.
  • The times on and off watch and the names and signatures of the operators concerned.
  • Time of arrival and departure from port/ports and the names of the port/ports.
  • The position of the vessel, at least once a day, unless not permitted by the vessels rules.
  • The names of the stations worked and frequencies used.
  • The times communications commenced and were completed.
  • A summary of all communications relating to distress, urgency and safety traffic.
  • A summary of all communications exchanged between the vessel and other stations, names of the stations, frequencies used, times commenced, times completed, strength and readability of the stations signals, difficulties experienced, etc.
  • A reference to important service incidents, such as failures of power supply or apparatus failure.

Condition of the batteries, which should be maintained in a fully charged condition when at sea (daily entries prescribed).

  • Daily time checks, including errors observed and corrections made to the prescribed clock for the radio installation.
  • Condition of the emergency transmitter and emergency receiver daily.
  • Condition of the portable lifeboat radio (weekly).


A reliable clock, with a dial of not less than 5 inches in diameter, the face of which should be marked to indicate the silence periods, should be securely mounted within sight of the operating position of the radiotelephone installation.

Restrictions while in port

Vessels in harbour may not use their radio installations at all while alongside a wharf, quay or jetty, except for the purpose of authorised tests or reporting their departure on VHF.

Other Restrictions

It is forbidden to:

  • Exchange traffic other than distress, urgency and safety traffic on 2182 4125 kHz and channel 16.
  • Exchange unnecessary signals of any kind.
  • Use radiotelephone installations for conversations other than those necessary for the transmission of authorised messages or radiotelephone calls.
  • To use offensive language.
  • Use the radio apparatus whilst the vessel is tied up alongside a wharf, pier or jetty inside any harbour or port or when the vessel is anchored inside port limits.
  • Disclose the contents of telegrams, messages and telephone calls.
  • Install or be in possession of unlicensed apparatus.
  • Interfere or cause interference to other transmissions.

Stations should listen before calling

Except when in DISTRESS, a station wishing to call should listen on the calling frequency for a reasonable period to ensure that there is no distress traffic in progress and that interference will not be caused to other communications already in progress; and should check the time to ensure that the SILENCE PERIODS are not violated.

Control of Working

  • Except in the case of DISTRESS, the coast station controls the communications in their area and ship stations may not interfere with the working of the coast stations. They should listen on the required frequencies before calling.
  • In DISTRESS situations, the vessel in distress controls the communications unless it hands over control to another station, usually the nearest coast station and/or the rescue vessel.

Calling Frequencies (VHF)

Channel 16 is both the calling and the distress frequency for the use of VHF ship stations.

  • Apart from DISTRESS CALLS, DISTRESS TRAFFIC, URGENCY AND SAFETY SIGNALS and MESSAGES, i.e. distress messages, for which it is obligatory, these frequencies may be used ONLY for calls and answers and NOT for passing messages, etc.
  • Messages should be transmitted on working frequencies allocated to the stations. The use of channel 16 for the transmission of messages is FORBIDDEN.
  • Apart from DISTRESS, URGENCY and SAFETY communications, calling signals preparatory to the exchange of traffic should not exceed ONE MINUTE when using channel 16.
  • When a station does not reply to a call sent three times at intervals of two minutes, calling should cease and may be renewed only after an interval of 15 minutes, but if interference will not be caused to other communications, calls may be renewed after a shorter period than 15 minutes, but not less than THREE minutes. Before renewing a call, the calling station should ascertain that the station called is not in communication with another station, e.g. on another frequency. Stations must not radiate a carrier between calls.

Silence Periods

  • During 3 minute periods on each hour and each half hour, e.g. 0000-0003 0030-0033, all transmissions on channel 16 should cease except transmissions concerning DISTRESS, URGENCY and SAFETY and a listening watch kept on channel 16, in order to allow any weak signals of any vessel in distress to be heard without interference.
  • Stations wishing to call on channel 16 should always check the time to ensure that the SILENCE PERIODS are not violated.
  • The first minute of the silence periods should be reserved for DISTRESS calls, the second minute for MAYDAY RELAYS, if there are Maydays at the time, and the third minute for URGENCY signals and URGENCY messages, if there are no maydays or mayday relays at the time. Navigation warnings may be announced just before the end of the Silence Periods and the messages transmitted just after the Silence Periods, preferably on a working frequency, which should be announced on channel 16.
  • All stations should avoid causing interference on these transmissions and should listen until they are certain that the transmissions are of no concern to them.

Calling Procedure

See Radio Calling Procedure.

Phonetic Alphabet and Figure Code

See Phonetic Alphabet


  • John C. Payne, Marine Electrical & Electronics Bible, Sheridan House, ISBN 1574090607


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