Marine VHF radio

thumb|A standard handheld marine VHF, mandatory on larger seagoing vessels under the GMDSS rules

thumb|A VHF set and a VHF channel 70 DSC set, the DSC on top

thumb|A vintage (76–89) marine VHF radiotelephone

Marine VHF radio is a worldwide system of two-way radio transceivers on ships and watercraft used for bidirectional voice communication from ship-to-ship, ship-to-shore (for example with harbormasters), and in certain circumstances ship-to-aircraft. It uses FM channels in the very high frequency (VHF) radio band in the frequency range between 156 and 174 MHz, designated by the International Telecommunication Union as the VHF maritime mobile band. In some countries additional channels are used, such as

The first marine radio transmitters used the longwave bands. During World War I amplitude modulation was developed, and in the 1920s spark radiotelegraphy equipment was replaced by vacuum tube radiotelephony allowing voice communication. Also in the 1920s, the ionospheric skip or skywave phenomenon was discovered, which allowed lower power vacuum tube transmitters operating in the shortwave bands to communicate at long distances.

Hoping to foil German detection during the World War II Battle of the Atlantic, American and British convoy escorts used Talk-Between-Ships (TBS) radios operating on VHF.

Types of equipment

Sets can be fixed or portable. A fixed set generally has the advantages of a more reliable power source, higher transmit power, a larger and more effective antenna and a bigger display and buttons. A portable set (often essentially a waterproof, VHF walkie-talkie in design) can be carried on a kayak, or to a lifeboat in an emergency, has its own power source and is waterproof if GMDSS-approved. A few portable VHFs are even approved to be used as emergency radios in environments requiring intrinsically safe equipment (e.g. gas tankers, oil rigs, etc.).

Voice-only

Voice only equipment is the traditional type, which relies totally on the human voice for calling and communicating.

Many lower priced handheld units are voice only as well as older fixed units.

Digital selective calling

DSC equipment, a part of the Global Maritime Distress and Safety System (GMDSS), provides all the functionality of voice-only equipment and, additionally, allows several other features:

The ability to call another vessel using a unique identifier known as a Maritime Mobile Service Identity (MMSI). This information is carried digitally and the receiving set will alert the operator of an incoming call once its own MMSI is detected. Calls are set up on the dedicated VHF channel 70 which DSC equipment must listen on continuously. The actual voice communication then takes place on a different channel specified by the caller.
A distress button, which automatically sends a digital distress signal identifying the calling vessel and the nature of the emergency
A built in GPS receiver or facility to connect an external GPS receiver so that the user's location may be transmitted automatically along with a distress call.

When a DSC radio is bought new the user will get the opportunity to program it with the MMSI number of the ship it is intended to be used on. However to change the MMSI after the initial programming can be problematic and require special proprietary tools. This is allegedly done to prevent theft.

Automatic identification system

More advanced transceiver units support AIS. This relies on a GPS receiver built into the VHF equipment or an externally connected one by which the transceiver obtains its position and transmits this information along with some other details about the ship (MMSI, cargo, draught, destination and some others) to nearby ships. AIS operates as a mesh network and full featured units relay AIS messages from other ships, greatly extending the range of this system; however some low-end units are receive only or do not support the relaying functionality.

AIS data is carried on dedicated VHF channels 87B and 88B at a baud rate of 9,600bit/s using GMSK modulation and uses a form of time-division multiplexing.

Text messaging

Using the RTCM 12301.1 standard it is possible to send and receive text messages in a similar fashion to SMS between marine VHF transceivers which comply with this standard. However, as of 2019 very few transceivers support this feature. The recipient of the message needs to be tuned to the same channel as the transmitting station in order to receive it.

Regulation

In the United States, any person can legally purchase a Marine VHF radio and use it to communicate without requiring any special license as long as they abide by certain rules, but in a great many other countries a license is required to transmit on Marine VHF frequencies.

In the United Kingdom and Ireland and some other European countries both the operator and the equipment must be separately licensed. A Short Range Certificate is the minimum requirement to use an installed marine VHF radio. This is usually obtained after completing a course of around two days and passing an exam. This is intended for those operating on lakes and in coastal areas whereas a Long Range Certificate is usually recommended for those operating further out as it also covers HF and MF radios as well as INMARSAT systems. Installations fixed on a particular vessel require a Ship Radio License. Portable equipment that could be used in multiple craft, dinghys etc. required a Ship Portable Radio Licence.

Automatic Transmitter Identification System (marine)

For use on the inland waterways within continental Europe, a compulsory Automatic Transmitter Identification System (ATIS) transmission conveys the vessel's identity after each voice transmission. This is a ten-digit code that is either an encoded version of the ship's alphanumeric call sign, or for vessels from outside the region, the ship MMSI prefixed with "9". The requirement to use ATIS in Europe, and which VHF channels may be used, are strongly regulated, most recently by the Basel agreements.

Channels and frequencies

A marine VHF set is a combined transmitter and receiver and only operates on standard, international frequencies known as channels. Channel 16 (156.8 MHz) is the international calling and distress channel. Transmission power ranges between 1 and 25 watts, giving a maximum range of up to about 60 nautical miles (111 km) between aerials mounted on tall ships and hills, and between aerials mounted on small boats at sea level. Frequency modulation (FM) is used, with vertical polarization, meaning that antennas have to be vertical in order to have good reception. For longer range communication at sea, marine MF and marine HF bands and satellite phones can be used.

Half-duplex channels here are listed with the A and B frequencies the same. The frequencies, channels, and some of their purposes are governed by the ITU. For an authoritative list see. The original allocation of channels consisted of only channels 1 to 28 with 50 kHz spacing between channels, and the second frequency for full-duplex operation 4.6 MHz higher.

Improvements in radio technology later meant that the channel spacing could be reduced to 25 kHz with channels 60 to 88 interspersed between the original channels.

Channels 75 and 76 are omitted as they are either side of the calling and distress channel 16, acting as guard channels. The frequencies which would have been the second frequencies on half-duplex channels are not used for marine purposes and can be used for other purposes that vary by country. For example, 161.000 to 161.450 MHz are part of the allocation to the Association of American Railroads channels used by railways in the US and Canada.

{| class="wikitable sortable sticky-header-multi"

! rowspan=2 | Channel number

! colspan=2 | Frequencies (MHz)

! rowspan=2 |

! rowspan=2 | CEPT Mediterranean countries (sea, ocean)

! rowspan=2 | Rhine: main stem, river, canal, lake, pond, estuary

!  Ship , usually

!  Shore , usually

| 0 || 156.000 || 160.600

| Private, coast guard

| 1 || 156.050 || 160.650

|Ship-to-ship/shore, commercial and safety West Coast

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), Independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways.. (ship-to-shore full-duplex)

| 2 || 156.100 || 160.700

| Public BC Coast

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), Independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways.. (ship-to-shore full-duplex)

| 3 || 156.150 || 160.750

| Illegal for public use

| Public BC Coast/Inland

| Boat to Boat – Kawau

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), Independent radio networks, Customs Coast Guard, search and rescue

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways. (ship-to-shore full-duplex)

| 4 || 156.200 || 160.800

| Ship-to-ship/shore, commercial and safety East Coast and Inland

Canadian Coast Guard – Search & Rescue BC Coast

| Boat to boat Tutukaka/Raglan

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), independent radio networks, customs, coast guard, search and rescue

| Public correspondence (ship-to-shore full-duplex), independent radio networks

| 5 || 156.250 || 160.850

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), independent radio networks, authorities responsible

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 6 || 156.300 || 156.300

| Ship-to-ship and ship-to-air

| Distress ship-to-air

| Inter-ship working

| Ship-to-ship (commercial) also SAR: Ship-to-ship and ship-to-air

| Ship-to-ship and ship-to-air

| Ship-to-ship (limited to 1 watt) and ship-to-air

| 7 || 156.350 || 160.950

| General working channel

| Public correspondence (ship-to-shore full-duplex) port operations

| Navy

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 8 || 156.400 || 156.400

| Ship-to-ship

| Ship-to-ship East and west coasts, Lake Winnipeg

| Inter-ship working

| Ship-to-ship (commercial)

| Ship-to-ship

| Ship-to-ship (limited to 1 watt)

| 9 || 156.450 || 156.450

| Frequently used by pilots

| Calling , commercial and non-commercial.

| Ship-to-air for maritime support Atlantic and BC coasts

| Pilots, port operations

| Port operations

| VTS Ship-to-ship + port operations

| Marina pilots, marina operations, ship in a marina

| Marina pilots, marina operations, ship in a marina, limited to 1 watt

| 10 || 156.500 || 156.500

| Frequently used by HM Coastguard

| Ship-to-air – SAR and antipollution General working – Atlantic and BC coasts, Great Lakes

| Port operations

| Ship-to-ship port operations also SAR and oil cleanup only VTS on Gulf of Finland

| International waters ship-to-ship; customs, coast guard, navy

| Calling; ship-to-ship; customs, on-board working, limited to 1 watt; distress, safety, and calling

| 11 || 156.550 || 156.550

| Port operations

| Vessel Traffic Services – BC coast

| Port operations

| port operations, also the Saimaa Canal locks

| Navy

| Port operations

| 12 || 156.600 || 156.600

| Port operations

| VTS – San Francisco offshore Pilotage

| Vessel Traffic Services – BC coast

| Port operations, VTS

| Port operations

| port operations

| colspan=2 style="text-align:center;" | Commercial port operations, fishing port operations, pilots, ship in a fishing port, ship in a commercial port

| 13 || 156.650 || 156.650

| Bridge-to-bridge working

| Bridge-to-bridge safety : Vessels > 20m must maintain watch, Tx limited to 1 watt. Movable bridge / lock operations.

| VTS – BC coast Bridge-to-bridge safety

| Port operations, VTS

| Intership Nav Safety

| Pilots Ship-to-ship port operations

| Port operations, coast guard

| Ship-to-ship (limited to 1 watt)

| 14 || 156.700 || 156.700

| Port operations

| VTS – San Francisco bay and delta Pilotage

| VTS – BC coast Port and pilot ops

| Port operations

| Working channel for SAR authorities, Turku Radio (port operations)

| Port operations, navy

| Port operations

| 15 || 156.750 || 156.750

| On-board working, limited to 1 watt

| max. 1 W Intraship Ship-to-ship port operations

| Beach monitoring

| Radiocommunications on board a ship or in a group of boats towed or pushed, as well as those concerning the instructions for the maneuver bullish and docking, limited to 1 watt

| 16 || 156.800 || 156.800

| colspan=7 style="text-align:center;" | International distress, safety and calling All vessels equipped with VHF must maintain watch.

| Estuary (16 + 10). Not used on: main stem, river, canal, lake, pond.

| 17 || 156.850 || 156.850

| On-board working

|BC Coast Pilots

| Aquatic sports events

| max. 1 W Intraship Ship-to-ship port operations

| Port operations, navy, Maritime Gendarmerie

|Radiocommunications on board a ship or in a group of boats towed or pushed, as well as those concerning the instructions for the maneuver bullish and docking. (limited to 1 watt)

| 18 || 156.900 || 161.500

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), Independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 19 || 156.950 || 161.550

| Landside facilities: harbormaster, marinas.

| Canadian Coast Guard working channel

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), port operations

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 20 || 157.000 || 161.600

| Repeater operations

| Continuous weather Maritime Safety Service

| Public correspondence (ship-to-shore full-duplex) port operations

| Port operations, Public correspondence (ship-to-shore full-duplex)

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex), (limited to 1 watt Paris Underground canal)

| 21 || 157.050 || 161.650

| U.S. Coast Guard only

| Continuous marine broadcasts (WX 8)

| Continuous weather Maritime Safety Service

| Public correspondence (ship-to-shore full-duplex) port operations

| colspan=2 style="text-align:center;" | Port operations

| 22 || 157.100 || 161.700

| U.S. Coast Guard public working channel

| Canadian Coast Guard working channel

| Continuous weather Maritime Safety Service

| Public correspondence (ship-to-shore full-duplex) port operations

| Port operations, public correspondence (ship-to-shore full-duplex)

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 23 || 157.150 || 161.750

| HM Coastguard Maritime Safety Information: now on 62, 63, 64.

| U.S. Coast Guard Only

| Continuous weather Maritime Safety Service

| Public correspondence (ship-to-shore full-duplex) port operations

| Port operations, Public correspondence (ship-to-shore full-duplex)

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex), Independent radio networks

| 24 || 157.200 || 161.800

| UKSAR G/A Winching UKSAR TWC

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), Independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 25 || 157.250 || 161.850

| Maritime radio working channel

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), Independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 26 || 157.300 || 161.900

| HM Coastguard Maritime Safety Information

| Public correspondence (marine telephone operator)

|Canadian Coast Guard Duplex – Public Correspondence

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), Independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 27 || 157.350 || 161.950

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 28 || 157.400 || 162.000

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 31 || 157.550 || 162.150

| (The Netherlands) Marina channel public correspondence (ship-to-shore full-duplex)

| M1/37A || 157.850 || 157.850

| (As M1) Yacht clubs, race committees and marinas

| 60 || 156.025 || 160.625

| GOFREP on Gulf of Finland public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), Independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 61 || 156.075 || 160.675

| Illegal for public use

| GOFREP (Estonia) on Gulf of Finland Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), Independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 62 || 156.125 || 160.725

| HM Coastguard Maritime Safety Information

| Boat to boat – Waiheke/Whangaroa

| Public correspondence (ship-to-shore full-duplex) port operations

| Public correspondence (ship-to-shore full-duplex), independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 63 || 156.175 || 160.775

| HM Coastguard Maritime Safety Information (half-duplex)

| Boat to boat – Manukau

| Public correspondence (ship-to-shore full-duplex) port operations

| Coast Guard, port operations

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 64 || 156.225 || 160.825

| HM Coastguard Maritime Safety Information (half-duplex)

| Illegal for public use

| Public correspondence (ship-to-shore full-duplex) port operations

| Coast Guard, port operations

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore full-duplex)

| 65 || 156.275 || 160.875

| National Coastwatch Institution (NCI) and Independent Coastwatch Stations (http://www.seasafetygroup.org) Working Channel for communication with local mariners for radio checks and local sea conditions. Effective 1 March 2021.

| Marine assistance working channel

| Boat to boat – Coromandel

| Public correspondence (ship-to-shore full-duplex) port operations

| Coast Guard, port operations

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 66 || 156.325 || 160.925

| BC coast marinas

| Public correspondence (ship-to-shore duplex) port operations

| Public correspondence (ship-to-shore duplex), Independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 67 || 156.375 || 156.375

| UK Small Ship Safety Channel

| Working Channel, Marine Weather

| Maritime radio working channel

| VTS (Ship-to-ship + port operations)

| Coast Guard

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 68 || 156.425 || 156.425

| Non-commercial

| Maritime radio working channel

port operations, border guard authorities,

Also some yacht clubs and marinas

| Coast Guard

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 69 || 156.475 || 156.475

| Port operations

| Non-commercial

| Australian Navy

| Maritime radio working channel surf lifesaving

| Ship-to-ship port operations

| Navy

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 70 || 156.525 || 156.525

| colspan=7 | Digital Selective Calling

| Not used on: main stem, river, canal, lake, pond.

| 71 || 156.575 || 156.575

| Port operations

| Non-commercial

|Vessel Traffic Services – BC Coast

| Maritime radio working channel

| VTS (ship-to-ship + port operations) port operations

| Navy

| Port operations

| 72 || 156.625 || 156.625

| Ship-to-ship Frequently used by leisure craft

| Non-commercial ship-to-ship

| Ship-to-ship

| Ship-to-ship Ship-to-air

| Ship-to-ship, communications with a social (ship)

| Ship-to-ship, communications with a social (ship) (limited to 1 watt)

| 73 || 156.675 || 156.675

| HM Coastguard Safety Broadcasts

Backup Small Ship Safety

| Ship-to-ship

| Marinas working

| Ship-to-ship Ship-to-air (port operations)

| Port operations, Navy

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 74 || 156.725 || 156.725

| British Waterways/Canal and River Trust Channel (Canal and River System)

port operations

|Vessel Traffic Services – BC Coast

| Ship-to-ship

| Coast/Ship working

| port operations

| Port operations, navy, Maritime Gendarmerie

| Port operations

| 75 || 156.775 || 156.775

| Navigation related communications, limited to 1 watt

| Restricted ship-to-ship port operations

| Restricted ship-to-ship port operations, (limited to 1 watt)

| Port operations

| 76 || 156.825 || 156.825

| Restricted port operations

| Restricted ship-to-ship port operations, (limited to 1 watt)

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 77 || 156.875 || 156.875

| Ship-to-ship

| Ship-to-ship, communications with a social (ship)

| Ship-to-ship, communications with a social (ship), limited to 1 watt

| 78 || 156.925 || 161.525

| Non-commercial

| Public correspondence (ship-to-shore duplex) port operations

| Public correspondence (ship-to-shore duplex), independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 79 || 156.975 || 161.575

| Public correspondence (ship-to-shore duplex) port operations

| Customs, coast guard, search and rescue, port operations

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 80 || 157.025 || 161.625

| UK marina channel

| Repeater operations

| Coastguard radio working channel

| GOFREP on Gulf of Finland public correspondence (ship-to-shore duplex) port operations

| Customs, Coast Guard, search and rescue, port operations

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 81 || 157.075 || 161.675

| U.S. Government Use Only

| Repeater Operations

| Coastguard radio working channel

| GOFREP (Estonia) on Gulf of Finland public correspondence (ship-to-shore duplex) port operations

| Public correspondence (ship-to-shore duplex), independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 82 || 157.125 || 161.725

| U.S. Government use only

| Canadian Coast Guard working channel

| Coastguard radio working channel

| Public correspondence (ship-to-shore duplex) port operations

| Port operations

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 83 || 157.175 || 161.775

| U.S. Coast Guard use only

| Canadian Coast Guard working channel

| Public correspondence (ship-to-shore duplex) port operations

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 84 || 157.225 || 161.825

| HM Coastguard Maritime Safety Information: now on 62, 63, 64.

|Canadian Coast Guard Duplex – Public Correspondence

| Coastguard radio working channel

| Public correspondence (ship-to-shore duplex) port operations

| Public correspondence (ship-to-shore duplex), Independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 85 || 157.275 || 161.875

| UKSAR TWC (half-duplex)

| Radio telephone – full duplex

| Coastguard radio working channel

| Public correspondence (ship-to-shore duplex) port operations

| Navy

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 86 || 157.325 || 161.925

| HM Coastguard Maritime Safety Information: now on 62, 63, 64.

| Coastguard radio working channel

| Public correspondence (ship-to-shore duplex) port operations

| Navy

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 87 || 157.375 || 157.375

| Public correspondence port operations

| Public correspondence (ship-to-shore duplex), independent radio networks, customs, Coast Guard, search and rescue

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| 88 || 157.425 || 157.425

| Commercial, inter-ship only

| Public correspondence (ship-to-shore duplex), independent radio networks

| Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex)

| M2/P4 || 161.425 || 161.425

| (As M2) Yacht clubs, race committees and marinas

| (As P4) In France, some yacht clubs, marinas and race committees

| AIS 1 || 161.975 || 161.975

| colspan=8 | Automatic Identification System

| AIS 2 || 162.025 || 162.025

| colspan=8 | Automatic Identification System

| L1 || 155.500 || 155.500

Leisure activities

(Ship-to-ship) Used in the Nordic countries and Estonia

| L2

| 155.525

Leisure activities

(Ship-to-ship) Used in the Nordic countries and Estonia

| L3 || 155.650 || 155.650

Leisure activities

(Ship-to-ship) Used in Finland and Norway

| F1 || 155.625 || 155.625

Fishing

(Ship-to-ship) Used in the Nordic countries

| F2

| 155.775

Fishing

(Ship-to-ship) Used in the Nordic countries

| F3

| 155.825

Fishing, also recreational fishing

(Ship-to-ship) Used in the Nordic countries

Operating procedure

Marine VHF mostly uses half-duplex audio equipment and non-relayed transmissions. Ship to ship communication is over a single radio frequency (simplex), while ship to shore often uses full duplex frequency pairs, however the transceivers are usually half-duplex devices that cannot receive when transmitting even on a full-duplex channel. To transmit the user presses a "push to talk" button on the set or microphone which turns the transmitter on and the receiver off in a device with half-duplex audio, even on a full-duplex radio channel; on devices with full-duplex audio the receiver is left on while transmitting on a full-duplex radio channel. Communication can take place in both directions simultaneously on full-duplex channels when the equipment on both ends allows it.

==See also==

2182 kHz
Automated Maritime Telecommunications System
Maritime mobile amateur radio
Radio horizon
Ship-to-shore

References

External links

US Coast Guard basic radio information for boaters
Coast Guard marine channel listing (with frequencies)
US FCC marine channel listing (by function)
Canadian VHF Bands in the Maritime Service
VHF marine band plan in Turkey (Türkiye'deki VHF Deniz Telsiz Frekans Kanal Listesi)

fr:Bandes marines#Bande VHF