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Marine VHF Radios, Generally Speaking.

To help boaters communicate when with out sailing with; Marinas, other boaters, requests for assistance, and for Marine Safety with Coast Guard units, the Marine VHF Radio is the authorized and preferred device to use. Using VHF Marine radios also alerts other boaters close by to the dangers and hazards encountered and will involve them to respond for calls of assistance until Coast Guard rescue units can arrive. As the general rule of the sea is that all boaters are required to respond or assist to calls of help. Some of the newer Marine Radios have extra Marine Weather Channels to receive or listen to continuous weather and safety broadcasts for your area. Its a good idea to listen to these broadcasts before sailing as they are "customized" just for boaters on the waters.

Check out our Marine Weather Channel webpage

Although cell phones have been used, they only make direct calls and they are private calls and thus  hamper rescues as other boaters and rescue units cannot hear or make contact with you. Cell Phones have an Achilles Heel or weakness as; the poor transmit power of the phone (short range), height of the terrain, remoteness, and lack of cell towers. Cell towers are configured for high use demands and hence are mostly used for homes and highway usage designed to point and only operate for those directions. The Citizen Bands (CB) Public Radios of the late 1970's in which every trucker on the road and every kid in town had one are also not acceptable for marine use, even though they cover more range than that of a cell phone.


To operate and use a Marine Radio one must be aware of the strict guidelines, protocols, and procedures to follow. This due to Rescue Operations, safety, size of ships, and hundreds of people possibly using the same channel due to the distance. Users of Marine Radios also need to be aware of the radio channels designations, transmit power, usage, and radio differences from various manufacture some of these topics we will discuss briefly here.

Rules and Regulations?:

Each country has their own set of Marine Radio Rules which can change from time to time and hence they should be reviewed at the beginning of each season.

bulletGovernment of Canada, Marine Transportation


In Canada any person who transmits on a Marine Radio must now have their "own" Restricted Radio Operator’s Certificate – Marine ROC(M), to be more knowledgeable in how to operate and respond to the radio due to rescue operations, rather than the old days of just owning a ship's station license. One can obtain their ROC license from many different sources but the "best" option is to take one with a full teaching course which includes books as reference. These courses take more time to complete but explains all of the concepts and reasoning thereof and usually include safety concepts as well. Since the life of you and your family may depend upon it one day taking this course is well worth it. Also when one owns the manuals, they can at the beginning of each season reread them  to refresh oneself to remain sharp and respond fast in an emergency.  These cources also cover the operation of VHF-DSC emergency calls.

bullet Canadian Power and Sail Squadrons, Marine Radio Course

Transmit Power, Distance, and Antenna:

To have the best range for your Marine Radio the following should be considered. Since its your primary "safety device", do spend a bit more money in looking for higher end products. One should have "two" radios; a primary fixed station and secondary portable battery handheld unit for backups. Small Sailboats can encounter scenarios that when the mast that the antenna is mounted to, is laid down on the boat (eg: trailering) can render the radio more or less useless. The antenna or cable can also become damaged in this process or the antenna could be damaged from high winds en route trailering on the highway. Some small sailboats when rafted all together can rock or sway back and forth with the top of the masts colliding from the big waves of large power boaters racing close by. Larger Sailboats also have dinghy's to access the shoreline and usually bring their portables with them.

Transmit Power: When in harbor close to the marina and near other boaters, its preferred to use the lower power settings for short distance communications. This also helps out small handheld radios in prolonging the battery life. But in; hilly terrain, far from shore, or in an emergency, the highest power setting is the best one to use. Most radios have Low/Medium/High power settings of 1/5/25 watts and more power helps for longer distances. Some radio channels are designated to use lower power levels to limit interference when sharing with others.

Distance: VHF Radios transmit line of sight, hence it is real important to mount the antenna on the "highest height" (mast/rooftop) on the boat.  Sometimes the size of boat and type can predetermine the antenna style to be used. Some antennas are designed to be extra long in length to overcome low mounting heights and can be folded down (hinged) on deck to pass under low bridges or when trailering. Due to the curvature of the earth, an antenna on a boat mounted 12 feet above sea level has a line of sight about 5 nautical miles, thus two boats set far apart could talk to each at 10 nautical miles with  the higher transmit power increasing range. Coast Guard stations have their shore based antennas mounted extremely high up on high radio towers to give extra range of 60 nautical miles (110 km), and can have multiple towers along the shoreline all connected via phones lines back to the station to increase the coverage area.

Antenna: The type of VHF antenna, design, and its rated gain, can help boost the radio signal. Some antennas that are mounted low are designed to compensate slightly for this low height by being quite tall or long in length 8-10 feet, and have a small wire continuously being wrapped around a fiberglass rod, and they also have a hinge point at the base to allow the antenna to be laid down flat on deck for low bridges or when the boat in on the trailer. Sailboats usually mount their antennas high up on the top of their masts and hence the antenna needs not to be physically as long and must be far lighter in weight. They also have small wire coil built-in the base of the antenna to reduce the length of the antenna before the single wire whip, as with the extra height they all ready have more range/distance.

Antenna Cable: Another consideration is line losses. The overall cable length, quality or type of coax cable being used, and how many splices/connectors are in between the radio and antenna, all combined together can weaken the transmit signal by up to 3 watts. Being an emergency device and wanting to be heard this is very important. Additionally the gain of the antenna (narrow, medium, or wide beam) that can focus the signal for more distance can have an effect, but the type of boat that it is to be used upon can pre-determine that selection. For example having a narrow beam antenna high up on a sailboat's mast when the boat is swinging or heeling can point some of the signal into the sky rather than across the water equally.

 DSC-Digital Selective Calling & GPS:

DSC: Some of newer and higher quality Marine Radios now include the new Digital Selective Calling. That can make calls electronically only on the designated DSC channel 70, and these calls do not use the microphone. Its easier to understand if one can think of the concept, that your radio now has two separate radios built in to one, "one for voice calls" and "one for electronic calls" but both listening for calls at the same time. These Electronic DSC calls are faster to send and can travel 20% farther and hundreds of calls can share the same channel far more efficiently. Overall DSC is great for making emergency calls, for example; when a ship is sinking taking on water fast, and is seconds away from the ship batteries to be flooded, just press the Emergency Button and in just one second your MMSI# and GPS position are transmitted.

GPS: The way that these radios operate is that each owner of a DSC radio applies for and receives their own personal Maritime Mobile Service Identity Number or MMSI that they program into their DSC radio. Each time the DSC radio transmits it will now include your personal MMSI number. These DSC Radios can also transmit your GPS location as well, either from it being built-in on your newer DSC Radio or from an attached GPS chart plotter/fish finder unit wired to it for the older models.

bulletCanadian Coast Guard: MMSI# application

When the emergency button is pressed on your DSC radio, both your MMSI# and your GPS location are transmitted in one second. When the Coast Guard Station hear your call electronically, it is displayed on their computer screen with your immediate location and your MMSI#.  Overlaid on the screen can be the areas water current, wind factors, shoreline, so the Coast Guard can also plot an additional drift pattern circle of where your disabled vessel could end up to aid in the rescue search. There is also a belief that they can also force a poll or resend of your DSC's GPS location to also reconfirm and to additionally find your location. In accessing your MMSI number the Coast Guard can additionally find all your submitted emergency info such as your name, address, family, boat type and boat info, to aid in the rescue and who to contact.

One can make DSC calls to other boaters and find out their position, when you are on a voice channel your DSC radio can alert you to incoming DSC calls and logs them. There are also preconfigured DSC messages that you can select to be sent out in your DSC call. Upon receiving DSC you can briefly respond to it and then go to a voice channel and further communicate more with them.

Sailing Clubs can also have a group MMSI# that when any messages are directed to the group MMSI, it will also be received by all ships within that group.

AIS-Automatied Identification:

Likewise with DSC calls, Larger ships and Vessels are required to transmit their current position and boat info constantly every minute for navigation safety just like airplanes. Some newer VHF DSC marine radios also have an AIS Receiver built in to display the location of larger vessels close by.

Marine Radio Channel Modes: A/B/I

Channels: Each Marine Radio Channel has a designated usage, power rating, and purpose, thus one must know in advance what each channel is for to prevent miscommunication or extra traffic. There are Emergency Channels, port operations, lock operations, ship to ship, ship to shore, hailing, working on board, marine safety, coast guard, marinas, Yacht and Sailing Clubs, and radio telephone calls.

Thus some channels can be half or full duplex, or basically use a single or a dual set of frequencies, some channels may Transmit (TX) and Receive (RX) on the exact same frequency, while other channels depending on usage may invoke using two separate frequencies, one for the Transit and one for Receive, for example: to communicate via radio to shore based telephone operators.

Modes: Not everything is the same across the board for channel frequencies as they can vary for the country being used. Over time there has been changes; new technology, radio standards, and keeping of older radios compatible with the newer added frequencies. To make it easier for the public, radios modes are standardized into 3 modes of operation (A, B, I).

bulletA-Mode, United States, reserve some frequencies for their own personal use.
bulletB-Mode, Canada.
bulletI-Mode, International.

Note: Only on those channels with different modes eg: 21A, 21B, they may not be able to cross-communicate with each other as they use a different frequencies. The Emergency Channel 16, Hailing Channel 9, and Marina Channel 68, are the same, regardless of modes.

The following list gives a "general description" of some the radio channels, frequencies, and usage.


List of Maritime Frequencies, Channel Number - Frequency - Usage

01A 156.050 156.050 Commercial
05A 156.250 156.250 Commercial
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
12 156.600 156.600 Port Operations, vts
13 156.650 156.650 Port Operations & Intership (bridge to bridge), Ships >20 meters keep listening watch in US waters
14 156.700 156.700 Port Operations, Commercial, vts
15 ------- 156.750 Environmental Receive Only Class C EPIRBSs
16 156.800 156.800 Calling and Distress, Ships to keel listening watch on this channel.
17 156.850 156.850 State & local Government 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
21B 161.650 161.650 Canadian Coast Guard, VBA-4 Sault Ste. Marie area, operated by Thunder Bay Coast Guard.
22A 157.100 157.100 Coast Guard Liaison
23A 157.150 157.150 U.S. Coast Guard
23B 161.750 161.750 Coast Guard
24 157.200 161.800 Radio telephone
24B 161.800 161.800 Radio telephone
25 157.250 161.850 Radio telephone
25B 161.850 161.850 Radio telephone
26 157.300 161.900 Radio telephone
26B 161.900 161.900 Radio telephone
27 157.350 161.950 Radio telephone
27B 161.950 161.950 Radio telephone
28 157.400 162.000 Radio telephone
28B 162.000 162.000 Radio telephone
63A 156.175 156.175 Commercial
65A 156.275 156.275 Port Operations
66A 156.325 156.325 Port Operations
67 156.375 156.375 Commercial
68 156.425 156.425 Non-Commercial, Marinas
69 156.475 156.475 Non-Commercial
70 156.525 156.525 Digital Selective Calling (no voice communications alowed)
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 (intership only)
77 156.875 156.875 Commercial
78A 156.925 156.925 Non-Commercial
79A 156.975 156.975 Commercial
80A 157.025 157.025 Commercial
81A 157.075 157.075 US Government
82A 157.125 157.125 US Government
83A 157.175 157.175 US Coast Guard
83B 161.775 161.775 Canadian Coast Guard Thunder Bay Weather Forecasts
84 157.225 161.825 Radio telephone
85 157.275 161.875 Radio telephone
86 157.325 161.925 Radio telephone
87 157.375 161.975 Radio telephone
88 157.425 162.025 Commercial
88A 157.425 157.425 Commercial (intership only)
AIS1 161.975 161.975 AIS Automatic Identification Systems
AIS2 162.025 162.025 AIS Automatic Identification Systems


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