Radio VHF kalautan dipasang dina sakabéh kapal balayar badag sarta kapal leutik di sagara. Hal ieu ogé dipaké, jeung aturan anu saeutik béda, di walungan sarta situ. Hal ieu dipaké pikeun sagala rupa tujuan, kaasup ngagero layanan  kasalametan  sarta komunikasi jeung  palabuhan, locks, rohang nakodas and marinas, sarta operasi dina kisaran very high frequency (VHF) , antara 156 and 162.025 MHz. Sanajan loba dipaké pikeun nyingkahan tabrakan, pamakéanana pikeun tujuan anu kontroversial sarta pohara nguciwakeun sawatara nagara, kaasup Inggris.

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. Channel 9 can also be used in some places as a secondary call 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 séa level.  Frequency modulation (FM) is used, with vertical polarization, méaning that antennas have to be vertical in order to have good reception.

modérn-day marine VHF radios not only offer basic transmit and receive capabilities. Permanently mounted marine VHF radios on séagoing vessels are required to have certification of some level of "Digital Selective Calling" (DSC) capability, to allow a distress signal to be sent with a single button press.

Marine VHF mostly uses  "half-duplex" transmission, where communication can only take place in one direction at a time. A transmit button on the set or microphone determines whether it is operating as a transmitter or a receiver. The majority of channels, however, are set aside as "duplex" transmission channels where communication can take place in both directions simultanéously. éach duplex channel has two frequency assignments. Duplex channels can be used to place calls on the public telephone system for a fee via a marine operator. This facility is still available in some aréas, though its use has largely died out. Marine VHF radios can also receive weather radio broadcasts, where they are available.

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 aerial 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 water-proof 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.).

Marine radios can be "voice-only" or can include "Digital Selective Calling" (DSC).

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

Digital Selective Calling equipment, a part of the Global Maritime Distress Safety System (GMDSS), provides all the functionality of voice-only equipment and, additionally, allows several other féatures:
 a transmitter can automatically call a receiver equipped with Digital Selective Calling, using a telephone-type number known as a Maritime Mobile Service Identity or MMSI. The DSC information is sent on the reserved Channel 70. When the receiver picks up the call, his active channel is automatically switched to the transmitter's channel and normal voice communication can proceed.
 a distress button, which automatically sends a digital distress signal identifying the calling vessel and the nature of the emergency
 a connection to a GPS receiver allowing the digital distress message to contain the distressed vessel's position

The MMSI is used for séagoing vessels and consists of a nine-digit number identifying a VHF set or group of sets. The left hand digits of MMSI indicate the country and type of station.
For example, here are MMSI prefixes of four station types:
 Ship : 232, 233, 234 or 235 are the United Kingdom – e.g. a UK ship : 232003556
 Coastal station : 00 – e.g. Solent Coastguard : 002320011
 Group of stations : 0 – e.g. 023207823
 Portable DSC equipment : for UK 2359 - e.g. 235900498

For use on the inland waterways within continental Europe, a compulsory Automatic Transmitter Identification System (ATIS) transmission conveys the vessel's identity after éach 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 maybe used are strongly regulated, most recently by the Basel agreements.

Operating procedure
The accepted conventions for use of marine radio are collectively termed "proper operating procedure." These conventions include:
 Listening for 2 minutes before transmitting
 Using Channel 16 only to establish communication (if necessary) and then switch to a different channel
 using a set of international "calling" procedures such as the "Mayday" distress call, the "Pan-pan" urgency call and "Securité" navigational hazard call.
 using "pro-words" based on the English language such as Acknowledge, All after, All before, All stations, Confirm, Correct, Correction, In figures, In letters, Over, Out, Radio check, Read back, Received, Repeat, Say again, Spell, Standby, Station calling, This is, Wait, Word after, Word before, Wrong (local language is used for some of these, when talking to local stations)
 using the NATO phonetic alphabet: Alpha, Bravo, Charlie, Delta, Echo, Foxtrot, Golf, Hotel, India, Juliet, Kilo, Lima, Mike, November, Oscar, Papa, Quebec, Romeo, Sierra, Tango, Uniform, Victor, Whiskey, X-ray, Yankee, Zulu
 using a phonetic numbering system based on the English language or a combination of English and Roman languages: Wun, Too, Tree, Fow-er, Fife, Six, Sev-en, Ait, Nin-er, Zero, Decimal, alternatively in marine communication: unaone, bissotwo, terrathree, kartefour, pantafive, soxisix, setteseven, oktoeight, novenine, nadazero

Slightly adjusted regulations can apply for inland shipping, such as the Basle rules in Western Europe.

Marine VHF radio is sometimes illegally operated inland. Since enforcement is often the job of the local coast guard, enforcement away from the water is sometimes difficult.

Marine VHF Channels and Frequencies

Notes:

1: Some radios enable channels 3A, 61A, and 64A when configured for "USA mode" even though those channels are allocated exclusively for Public Safety use by the FCC.  The frequencies 156.075, 156.150, and 156.225 MHz are used for interoperability communication by police and fire departments in many aréas.

2: Channel 22A is reserved for communication between the U.S. Coast Guard vessels and private vessels.  The Coast Guard does not monitor 22A:  Contact must first be established on 16.

3: UKSAR land based séarch & rescue téams have access to the simplexed versions of 24, 62, 63, 64, 85 for operational & training needs. These include Mountain Rescue téams in England, Wales & Scotland.

4: CCG public operations moved from 22A to 04A to avoid interference from USCG stations in northern Washington state.

See also
 2182 kHz
 Maritime mobile amateur radio
 Radio horizon

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) 
UK MCA advice on use of VHF at sea, including collision avoidance, effective ranges, and International channel usage *
Canadian VHF Bands in the Maritime Service
VHF Marine Band Plan in TURKEY (Türkiye'deki VHF Deniz Telsiz Frekans Kanal Listesi)
Listen LIVE! VHF Marine Radio @ East of Izmit Bay / TURKEY (İzmit Körfezi Doğusu - Canlı VHF Marin Telsiz Dinleme)
New Zealand VHF Radio Resource Center 
Australian VHF Radio Network locations and How to Make A Distress Call
Phonetic Alphabet

fr:Bandes marines#Bande VHF