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Using VHF Marine Radios

Using Marine RadioWhat are Marine Radios?

One of the most important pieces of safety equipment on board your ship is your two-way radio. VHF Marine radios use the radio frequency range between 156.0 to 162.025 MHz, inclusive. Marine radios have a specific set of frequencies assigned to predetermined channels on the radio, and each channel is designated for a specific type of communication. For example, channel 16 (156.8 MHz) is the international calling and distress channel on all marine radios. Permanently mounted marine radios (also called fix-mount) on seagoing vessels are also required to have  "Digital Selective Calling" (DSC) capability, to allow a distress signal to be sent with a single button press. If you plan to travel more than a few miles offshore it is a good idea to have a second radio as well, one fix-mount and one handheld is best.

A marine VHF radio is a combined transmitter and receiver. Marine VHF radios primarily use "simplex" transmission, this means communication takes place in one direction at a time. A transmit button on the set or microphone determines whether it is transmitting or receiving. Some channels are set as "semi-duplex" transmission, making it possible to communicate in both directions simultaneously. Each semi-duplex channel has two frequency assignments.


Types of Marine Radios

There are basically two types of marine radios, handheld, and fixed-mount. Handheld marine radios are more limited in power and therefore have a shorter range, but can be moved from one boat to another.  Fixed-Mount marine radios, just as the name implies are permanently mounted. They deliver more power and have a longer range because they are run off electrical connections on your boat. Maximum transmission power for marine VHF radios ranges from 5 watts on handhelds, to 25 watts on fix-mount.


Communication Range

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; 6 mi) between aerials mounted on small boats at sea level, who are transmitting on a 25-watt radio. Antennas need to be vertical in order to have the best reception.  Marine radios are intended mainly for short-range communications, generally 5-10 miles. To communicate at longer ranges you will normally need a satellite telephone or an MF/HF marine radio-telephone. Marine radio-telephone equipment normally operates between 2 - 26 MHz using single sideband emissions. MF/HF marine radio-telephones can also be used to receive high seas weather broadcasts, and by using a computer and a special interface provided by some coast stations, can provide Internet email.


Marine VHF vs Other VHF Radios

A marine VHF radio is different from other VHF radios used for land or air communications. Marine radios are specifically designed for communications on the waterways. They are installed on all large ships and most seagoing small craft, and with slightly different regulation on rivers and lakes. Not all VHF radios are designated for marine use.  It is important that you use two-way radios specifically approved for marine use when on the waterways. Other VHF radios should not be used as they will not have the proper frequency settings. Also, today's marine radios have other features such as NOAA weather alert channels that would not be available on land mobile VHF radios.


Do you need an FCC License to use Marine Radios?

An FCC radio license is no longer required for vessels traveling in U.S. waters using a VHF marine radio, radar or EPIRB, and which is not otherwise required to carry radio equipment. A license is necessary however for any vessel required to carry a marine radio, on an international voyage, or carrying an HF single sideband radiotelephone or marine satellite terminal. FCC license forms, including applications for ship and land station radio licenses, can be downloaded from the FCC website. For more information go to

Marine Radios With Land Channels

Some marine radios also have land channels that can be used while in port. These land channels do require an FCC license here in the USA. Since most users travel to various ports, an Itinerant License should be obtained. We offer FCC licensing Services and we can help you get either an itinerant license for a business or non-profit organization. Or if your radios are for personal use, you can obtain a GMRS License. This will allow the use of the land channels while in port in the USA.

Using Marine Frequencies

There are many uses for marine radios including rescue services, communicating with harbors, locks, bridges, and marinas, and general ship-to-ship and ship-to-shore communications.  Understanding how to use your radio, and which channels are used for each type of communication is very important.  There are regulations in place for monitoring and using your marine radio. These regulations are established in the US by the Federal Communications Commission (FCC), and in other countries by their similar regulating agencies. This is an overview of the uses for the various channels and frequencies.

The most important channels on your marine radio are 06, 09, 13, 16, 09, 22, and 70.  The other most used channels for recreational ships are 68, 69, 71, and 72.

  • Channel 16 - Distress calling and safety, ship-to-ship or ship-to-coast. Users must switch to a "working" channel after making initial contact (except in emergencies). All vessels must monitor Channel 16 when not using the radio for other purposes.
  • Channel 09 - Secondary calling channel (a new FCC Rule has designated Channel 9 to be the preferred channel for calling). The purpose of this change is to free Channel 16 for distress calls.
  • Channel 06 - Ship-to-ship safety messages, and communication with search and rescue and Coast Guard vessels and aircraft.
  • Channel 13 - Ship to bridge or lock master, ship to tender calls. Commercial vessel use primarily. One watt of power, used for close in communicating.
  • Channel 22 - Used to speak with Coast Guard after initial contact on Channel 16. Coast Guard also makes safety broadcasts on this channel.
  • Channel 70 - Digital Selective Calling. Those vessels with DSC radios should use this channel for distress and calling channel instead of 16.
  • Channel 68, 69, 71, and 72 - Used solely for communications between vessels.

Calling A Ship by Radio

You may use channel 16 to hail a ship or shore station, but if you do so, you must immediately switch to a working channel.  It is recommended you use channel 9 for non-urgent communication when available.


Here is an example of a typical call:

  • Big Fish: "My Little Boat, this is Big Fish" (the name of the vessel, or MMSI being called, may be repeated 2 or 3 times if needed)
  • My Little Boat: "Big Fish, this is My Little Boat. Reply 68" (or some other proper working channel)
  • Big Fish: "68" or "Roger"


Storm Warnings

The Coast Guard announces storm warnings and other urgent marine information broadcasts on VHF channel 16, and 2182 kHz, before making the broadcasts on VHF channel 22A, and 2670 kHz, respectively. Storm warnings and forecasts are also made by NOAA Weather Radio.

Handy TipsHelpful Tips for Using a Marine Radio

  • At the start of a trip, always power on your radio and begin with a radio check.  Radio checks are allowed on channel 16. To perform a radio check, say "radio check" and your location. For example: "Radio check, Newport Harbor." This is useful for others testing their reception, and for you to gauge the range of your transmissions. The proper way to reply is "loud and clear in Bristol Harbor" or "5 by 5 in Hampton Cove"
  • Never use the MAYDAY call for anything but a true emergency.
  • All fixed-mount marine radios can transmit at either 25 watts or 1 watt. The maximum power from a handheld is typically 5 watts or 1 watt. With either type, if your radio contact is nearby, set the power setting to low (1 watt) to reduce the distance the signal carries beyond your target.
  • Show others on-board how to use the radio. In an emergency, if something happens to you make sure they know how to make a call.
  • Watch your language.  Not only is profanity over the air against the law, it will be particularly offensive to other boaters with children aboard.
  • To adjust the radio's speaker volume, turn on the radio and untune the squelch by turning the dial until static is heard over the speaker. Adjust the volume. Then re-tune Squelch just enough to make the static stop for most sensitive reception.
  • Radios sold in USA will include International band for waters outside US and WX band for receiving NOAA weather broadcasts.
  • Always monitor channel 16, an international standard for distress and hailing. All mariners are required to monitor this channel whenever their boat is in motion. If you are monitoring a second channel, you can use the scan button to toggle between channel 16 and the other channel. The monitor function will automatically switch to whichever channel transmission is heard.
  • Don't tie up a channel.  A radio conversation ties up the channel you are using. No one else within a 25 to 30 mile radius can use it until you sign off. There are only five channels available for pleasure boat-to-boat communication. Please be considerate.
  • The five channels designated for non-commercial ship-to-ship communications are 68, 69, 71, 72, and 78A. Channel 9 used to be in this group but has been re-designated as an alternate calling (but not distress) channel.
  • You may hail another vessel on channel 16 and then ask them to switch to another channel. However, sometimes when you switch to a working channel, you find it occupied. In that case, check the other four to find an empty one, then go back to 16 and say, "Your name, their name, channel #. For example: "Cowboy. This is Tambourine. Seven one."  Then switch to channel 71 and continue your conversation.
  • Channel 13 is for navigational use between vessels.  Large vessels in close proximity announce their intentions to one another on this channel. This is also the primary channel used at bridges and locks. Use this channel to announce your arrival to a bridge or lock tender, or to communicate with a nearby ship or other large vessel. You do not need to call on Channel 16 first.  Channel 13 serves both as a calling and a working channel. Transmission power on this channel is restricted to 1 watt, so be sure to switch your radio to low power.
  • Channels 6 and 22A are also important to pleasure boaters. Channel 6 is reserved for inter-ship safety use, primarily during search and rescue operations. Channel 22A is reserved for communications with the Coast Guard.  Remember, it is illegal to contact the Coast Guard for a radio check. Call another boat instead.
  • Speaking on the radio:
    • When speaking into the radio, hold the mic so that your fingers are clear of mic's speaker.
    • Press and hold the Push To Talk (PTT) button to speak. Hesitate for one second before speaking. Otherwise, your first words will be missed.
    • Release the Push To Talk (PTT) button when finished speaking to listen.
    • Only talk when all other parties on the frequency are silent. The strongest signal will dominate, which means if you speak over someone else, their communication will not be heard. This is critical for distress call reception.
    • Speak slowly and clearly. Radio waves can distort the sound of your voice, making clarity essential.
    • Use channel 16 for distress calls and hailing only. If you need to speak to another vessel, hail them on 16 and then immediately agree to switch up to another channel on the recreational band, such as channel 68, to carry on the conversation.
    • To hail another vessel or shore station, repeat their name 3 times. Then conclude with your vessel name. For example: "Blue Water, Blue Water, Blue Water.  This is Little Swimmer, OVER".
    • End transmissions with either the word "Over" (meaning I am done talking for the moment), or "Out" (meaning I am signing off).
    • Do not initiate your reply until the other station has indicated they are clear via the words "Over". Remember, if you talk over another person, only the strongest signal is heard.
    • When speaking on an open deck, be sure to shield the mic from the wind. Duck behind a console or block with a shirt before speaking. Otherwise, all that will be heard is rushing wind.  Likewise, when listening in windy conditions, you may hold the remote mic to your ear. It doubles as a speaker.


Distress Calls & Alerts

You may only have seconds to send a distress call. Here's the procedure for VHF Marine Channel 16 MAYDAY:

  1. Tune your VHF marine radio to channel 16. Unless you know you are outside VHF range of shore and ships, call on channel 16 first. If you have an MF/HF radio-telephone tuned to 2182 kHz, send the radio-telephone alarm signal if one is available.
  2. Give the distress signal "MAYDAY," spoken three times.
  3. Say the words "THIS IS", spoken once.
  4. Give the name of the vessel in distress (spoken three times) and call sign or boat registration number, spoken once.
  5. Repeat "MAYDAY" and name of vessel, spoken once.
  6. Give the position of your vessel by latitude or longitude or by bearing (true or magnetic, state which) and distance to a well-known landmark such as a navigational aid or small island, or in any terms which will assist a responding station in locating the vessel in distress. Include any information on vessel movement such as course, speed and destination.
  7. Nature of distress (sinking, fire etc.).
  8. Type of assistance needed.
  9. Number of persons on-board.
  10. Any other information which might facilitate rescue, such as length or tonnage of the vessel, number of persons needing medical attention, color hull, cabin, masks, etc.
  11. The word "OVER".
  12. Stay by the radio if possible. Even after the message has been received, the Coast Guard can find you more quickly if you can transmit a signal on which a rescue boat or aircraft can home.


For example:

  • OVER".

Repeat at intervals until an answer is received.

If you hear a distress call... from a vessel and it is not answered, then you must answer. If you are reasonably sure that the distressed vessel is not in your vicinity, you should wait a short time for others to acknowledge.


Other Alerts

The words "SECURITE, SECURITE, SECURITE" (French: sécurité) literally means that what follows is important safety information. Used as a heads-up call by shippers to alert others to the presence of dangerous debris in the water, or traffic alerts regarding large vessels in the area. The call should be followed with information about the alert, such as "this is the Ferry Blue Sea departing the dock Monterey Bay outbound Hampton Harbor bound for Newport." You may end with contact information, such as "Any concerned traffic can hail Blue Sea on channels 13 and 16. OVER."

"PAN-PAN, PAN-PAN, PAN-PAN" signifies there is an urgent situation on board, but that for the time being at least, there is no immediate danger to anyone's life or to the vessel itself. This is referred to as a 'state of urgency'. The correct usage is "Pan-Pan, Pan-Pan, Pan-Pan", followed by the intended recipient of the message, either "All Stations, All Stations, All Stations", or a specific station "Vancouver Coast Guard, Vancouver Coast Guard, Vancouver Coast Guard", the identification of the craft, its position, the nature of the problem and the type of assistance or advice required, if any.

If you hear any of these alert or emergency messages you must give them priority over the radio channel.


Digital Selective Calling

Digital Selective Calling (know as DSC) is a feature on all fixed-mount marine radios built since 1999. DSC allows you to send out an automatic distress call to the Coast Guard's Rescue 21 system, as well as to all DSC-equipped radios on vessels within your transmission range, with the push of a single button. The transmission can include your exact position, provided you have connected the radio to your onboard GPS. So, if you have a DSC radio and a GPS and they are not connected to each other, making that connection should be your highest priority. You also need a Marine Mobile Service Identity (MMSI) number.  

VHF maritime channel 70 (156.525 MHz) is authorized exclusively for distress, safety, and calling purposes using digital selective calling (DSC) techniques. No other uses are permitted.  Channel 70 is used to send distress alerts, safety announcements and for calling purposes under the Global Maritime Distress and Safety System (GMDSS). Many vessels are now equipped with DSC capability and are using channel 70 for this purpose. It is essential that this channel be protected against unauthorized uses.

Once you have an MMSI number programmed into your radio, the DSC feature has other uses you may find convenient. The most common is to hail your friends without announcing on Channel 16. Instead, you dial their MMSI number and your call is announced on their radio only, along with a notice of which channel you wish to communicate on. Any voice exchange that follows will still be transmitted to all radios monitoring the designated channel, but at least you have not announced to all listeners on Channel 16 your intention to have that conversation.


How To Obtain an MMSI Assignment

In order to obtain an MMSI, mariners required by regulation to carry a marine radio and those who travel outside the U.S. or Canada to foreign ports must apply to the FCC (Federal Communications Commission) for a ship station license or an amendment to a ship station license. State and local governments can generally obtain an FCC ship station license at no charge.

Mariners not required to carry a marine radio (e.g. recreational boaters) and who remain in U.S. waters can obtain an MMSI through approved organizations such as BOAT US 1-800-563-1536, SEA TOW 1-800-4SEATOW, U.S. Power Squadron, and Shine Micro (primarily for AIS). Most of these organizations provide MMSIs at no charge even to non-members.


Marine Channel Frequency Assignments

Below is a complete list of frequency channel assignments and the designated type of communication use of each marine channel.

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 & local govt maritime control
18A 156.900 156.900 Commercial
19A 156.950 156.950 Commercial
20 157.000 161.600 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.
65A 156.275 156.275 Port Operations
66A 156.325 156.325 Port Operations
67 156.375 156.375 Commercial. Used for Bridge-to-bridge communications in lower Mississippi River. Intership only.
68 156.425 156.425 Non-Commercial
69 156.475 156.475 Non-Commercial
70 156.525 156.525 Digital Selective Calling (voice communications not allowed)
71 156.575 156.575 Non-Commercial
72 156.625 156.625 Non-Commercial (Intership only)
73 156.675 156.675 Port Operations
74 156.725 156.725 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)
87 157.375 157.375 Public Correspondence (Marine Operator)
88A 157.425 157.425 Commercial, Intership only.
AIS 1 161.975 161.975 Automatic Identification System (AIS)
AIS 2 162.025 162.025 Automatic Identification System (AIS)


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