Marine VHF radio Totally Explained

Everything about Marine Vhf Radio totally explained

Marine VHF radio is installed on all large ships and most motorized small craft. It is used for a wide variety of purposes, including summoning rescue services and communicating with harbours and marinas, and operates in the VHF frequency range, between 156 to 174 MHz. Although it's widely used for collision avoidance, its use for this purpose is contentious and is strongly discouraged by some countries, including the UK.
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 5 nautical miles (9 km) between aerials mounted on small boats at sea-level. Frequency modulation is used.
Marine VHF mostly uses "simplex" transmission, where communication can only take place in one direction at a time. A transmit button on the set or microphone determines whether it's operating as a transmitter or a receiver. The majority of channels, however, are set aside for "duplex" transmissions channels where communication can take place in both directions simultaneously . Each duplex channel has two frequency assignments. This is mainly because, in the days before mobile phones and satcomms became widespread, the duplex channels could be used to place calls on the public telephone system for a fee via a marine operator. This facility is still available in some areas, though its use has largely died out. In US waters, Marine VHF radios can also receive weather radio broadcasts, where they're available, on receive-only channels wx1, wx2, etc.

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 to a lifeboat in an emergency, has its own power source and is more easily water-proofed.
Marine radios can be "voice-only" or can include "Digital Selective Calling". 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 GMDSS, provides all the functionality of voice-only equipment and, additionally, allows several other features:

a transmitter can call a receiver automatically using Digital Selective Calling on Channel 70, using a telephone-type number known as a Maritime Mobile Service Identity or MMSI
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 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 is the United Kingdom – for example a UK ship : 232003556

Coast : 00 – for example Solent Coastguard : 002320011

Group of stations : 0 – for example 023207823

Portable DSC equipment : for UK 2359 - for example 235900498

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

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: Wun, Too, Tree, Fow-er, Fife, Six, Sev-en, Ait, Nin-er, Zero, Decimal 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

Channel number	"A" frequency (MHz) Usually ship stations	"B" frequency (MHz) Usually coast stations
0	156.000	160.600	Private, coast guard Ⓐ
1	156.050	160.650		Public BC Coast
2	156.100	160.700		Public BC Coast
3	156.150	160.750		Public BC Coast/Inland
4	156.200	160.800		Ship-to-ship/shore, commercial and safety BC and East Coasts Ⓐ
5	156.250	160.850
6	156.300	160.900	Ship-to-ship Ⓐ
7	156.350	160.950
8	156.400	161.000	Ship-to-ship Ⓐ
9	156.450	161.050	Ship-to-ship Ⓐ	Alternative calling channel Ⓐ
10	156.500	161.100	Ship-to-ship Ⓐ
11	156.550	161.150
12	156.600	161.200
13	156.650	161.250	Ship-to-ship Ⓐ
14	156.700	161.300
15	156.750	161.350	Ship-to-ship Ⓐ
16	156.800	161.400	International distress, safety and calling Ⓐ
17	156.850	161.450	Ship-to-ship Ⓐ
18	156.900	161.500
19	156.950	161.550
20	157.000	161.600
21	157.050	161.650
22	157.100	161.700
23	157.150	161.750
24	157.200	161.800
25	157.250	161.850
26	157.300	161.900
27	157.350	161.950
28	157.400	162.000
60	156.025	160.625
61	156.075	160.675
62	156.125	160.725
63	156.175	160.775
64	156.225	160.825
65	156.275	160.875
66	156.325	160.925
67	156.375	160.975
68	156.425	161.275
69	156.475	161.075
70	156.525	161.125	Digital Selective Calling Ⓐ
71	156.575	161.175
72	156.625	161.225
73	156.675	161.275
74	156.725	161.325
75	156.775	161.375
76	156.825	161.425
77	156.875	161.475
78	156.925	161.525
79	156.975	161.575
80	157.275	161.625
81	157.075	161.675
82	157.125	161.725
83	157.175	161.775
84	157.225	161.825
85	157.275	161.875
86	157.325	161.925
87	157.375	161.975	Automatic Identification System Ⓑ
88	157.425	162.025	Automatic Identification System Ⓑ

Further Information

Get more info on 'Marine Vhf Radio'.

External Link Exchanges

Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:

<a href="http://marine_vhf_radio.totallyexplained.com">Marine VHF radio Totally Explained</a>

Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned.