VHF Radio

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WorldVHF_RadioVHF Radio
The fairly common Marine VHF Radio - Icom M80 H


VHF radio is mostly useful for line-of-sight operation, and as such it has a direct range of around 25 miles. Repeater operation with shore stations in elevated positions may expand that range considerably. Some modern VHF radios also have inbuilt Automatic Identification System (AIS) capability, allowing the user to view the location of other vessels within the immediate horizon as a sort of "poor man's radar". Since ships over 300 tons - and some fishing fleets - are now required to have an AIS transponder running at all times, this safety feature should reduce maritime collisions.

It is the preferred radio for use in port, and power should be reduced close to shore to avoid interference. To this end modern radios have a Hi-Lo power switch. Maximum output is generally 25W with low power setting being somewhere from 1W to 5W.

Other useful features include the ability to monitor the emergency channel (Ch 16) while being tuned to another operating channel, which is called "dual watch" capability.

It should be carefully noted that many VHF radios from the USA were built to an inferior AIS "standard" that only monitors a single AIS channel. It is now illegal to sell, import or manufacture such radios. Buyers should therefore be careful of "bargain" radios of US origin.


Also see the FCC Website (covers HF Marine Radio as well)

Order of Priority of Communications in Maritime Mobile Service

  • Distress calls, distress messages and distress traffic (MAYDAY).
  • Communications preceded by the urgency signal (PAN-PAN).
  • Communications preceded by the safety signal (SECURITE).
  • Communications relating to radio direction finding.
  • Communications relating to the navigation and safe movements of aircraft engaged in search and rescue operations.
  • Communications relating to the navigation, movements and needs of ships and weather observation messages destined for an official meteorological service.
  • Government radiotelegrams relative to the application of the United Nations Charter (ETATPRIORITENATIONS)
  • Government radiotelegrams with priority and government calls for which priority has been expressly requested (ETATPRIORITE)
  • Service communications relating to the working of the telecommunication service or to communications previously exchanged, e.g. service telegrams.
  • Government communications other than those shown ordinary private communications, RCT radiotelegrams (telegrams concerning persons protected in time of war by the Geneva Conventions of 12 August 1949) and press radiotelegrams.
  • The navigation warning should then be re-announced and broadcasted on the working frequency which was announced on the calling frequency.

Navigation warnings broadcasted by shipstations are usually intercepted and relayed by the responsible coast stations but when necessary the shipstations should repeat their navigation warnings at suitable intervals, e.g. when towing another vessel or when the responsible coast station has not acknowledged receipt.

Marine VHF Frequencies & Channels


The following table is correct for the USA only, and varies from ITU (International) standards. Most newer VHF radios have the capability to switch between "US" and "INT" mode. Both New Zealand and Canada use a variant system requiring special channel spacings. The NOAA weather frequencies listed are only available off mainland USA.

The channel numbers run from 01A to 88A in the left hand column. The frequencies in megahertz (MHz) are given for each designated channel, first the transmit MHz then the receive MHz. Against each channel is the authorised use for that channel. These are the channels found in most VHF marine radios marketed today - some earlier models will not have all channels and frequencies available.

01A 156.050 156.050 Port Operations and Commercial, VTS. Available only in New Orleans / Lower Mississippi area.
05A 156.250 156.250 Port Operations or VTS in the Houston, New Orleans and Seattle areas.
06 156.300 156.300 Intership Safety
07A 156.350 156.350 Commercial
08 156.400 156.400 Commercial (Intership only)
09 156.450 156.450 Boater Calling. Commercial and Non-Commercial.
10 156.500 156.500 Commercial
11 156.550 156.550 Commercial. VTS in selected areas.
12 156.600 156.600 Port Operations. VTS in selected areas.
13 156.650 156.650 Intership Navigation Safety (Bridge-to-bridge). Ships >20m length maintain a listening watch on this channel in US waters.
14 156.700 156.700 Port Operations. VTS in selected areas.
15 -- 156.750 Environmental (Receive only). Used by Class C EPIRBs.
16 156.800 156.800 International Distress, Safety and Calling. Ships required to carry radio, USCG, and most coast stations maintain a listening watch on this channel.
17 156.850 156.850 State Control
18A 156.900 156.900 Commercial
19A 156.950 156.950 Commercial
20157.000 161.600 Port Operations (duplex)
20A 157.000 157.000 Port Operations
21A 157.050 157.050 U.S. Coast Guard only
22A 157.100 157.100 Coast Guard Liaison and Maritime Safety Information Broadcasts. Broadcasts announced on channel 16.
23A 157.150 157.150 U.S. Coast Guard only
24 157.200 161.800 Public Correspondence (Marine Operator)
25 157.250 161.850 Public Correspondence (Marine Operator)
26 157.300 161.900 Public Correspondence (Marine Operator)
27 157.350 161.950 Public Correspondence (Marine Operator)
28 157.400 162.000 Public Correspondence (Marine Operator)
63A 156.175 156.175 Port Operations and Commercial, VTS. Available only in New Orleans/Lower Mississippi area.
65A156.275156.275 Port Operations
66A156.325 156.325 Port Operations
67 156.375 156.375 Commercial. Used for Bridge-to-bridge communications in lower Mississippi River. Intership only.
68156.425 156.425 Non-Commercial
69156.475 156.475 Non-Commercial
70 156.525 156.525 Digital Selective Calling (voice communications not allowed)
71156.575 156.575 Non-Commercial
72156.625 156.625 Non-Commercial (Intership only)
73156.675 156.675 Port Operations
74156.725 156.725 Port Operations
77 156.875 156.875 Port Operations (Intership only)
78A 156.925 156.925 Non-Commercial
79A 156.975 156.975 Commercial. Non-Commercial in Great Lakes only
80A 157.025 157.025 Commercial. Non-Commercial in Great Lakes only
81A 157.075 157.075 U.S. Government only - Environmental protection operations.
82A 157.125 157.125 U.S. Government only
83A 157.175 157.175 U.S. Coast Guard only
84 157.225 161.825 Public Correspondence (Marine Operator)
85 157.275 161.875 Public Correspondence (Marine Operator)
86 157.325 161.925 Public Correspondence (Marine Operator)
AIS 1161.975 161.975 Automatic Identification System (AIS)
AIS 2162.025 162.025 Automatic Identification System (AIS)
88A 157.425 157.425 Commercial, Intership only.

NOAA Weather Radio Frequencies

Channel Frequency (MHz)
WX1 162.550
WX2 162.400
WX3 162.475
WX4 162.425
WX5 162.450
WX6 162.500
WX7 162.525

See the NOAA Weather Radio Homepage for more information.

Emergency channels

Channel 16, 156.800MHz, is the international maritime distress frequency on VHF. This channel is also used for calling other vessels but you are expected to move your discussion to another channel after contact is made. Have a frequency in mind when calling another station.

The United States Coast Guard generally utilizes channel 22A, 157.100MHz, as its working channel although when establishing contact with them you should pay attention to the channel given to you by the Coast Guard station.

Channel 70 is also used as an international distress and calling channel for DSC. This channel is not used in conjunction with voice communications. Your radio should prompt you for a voice channel to move to before calling a station. If used for distress your radio should automatically switch to channel 16 after transmitting your digital distress signal on channel 70.

Fault Tracing

  • Ensure that the power supply is switched on.
  • Check that the voltage is correct.
  • Check that the transmitter and receiver are on the correct frequencies.
  • Check that the correct modes have been selected e.g. A3 A3H A3A A3J.
  • Check that the aerial/aerials is/are connected.
  • Check that the aerial/aerials is/are up and are not shorting anywhere.
  • Check all switches and visible connections.
  • Check fuses.
  • If voltage is low check flat batteries and recharge.
  • If voltage is correct but transmitter won't tune up check aerials and fuses.
  • If transmitter tunes up OK and you are unable to establish communication check that you are calling and listening on the correct frequencies. When calling always say where you are listening.
  • Try alternative aerial if available e.g. for portable lifeboat radio. Check that artificial aerial is disconnected.
  • If your transmitter is working satisfactory but you cannot establish communication check that you are within range of the station you are calling.


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


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