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Article: VHF Marine Radios

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    by Alan Sorum - Feature Writer for Boating & Sailing at suite101.com
    [email protected]

    A VHF (Very High Frequency) marine radio is essential safety gear that needs to be aboard all vessels. There are appropriate VHF's built for every type of watercraft. Manufacturers now produce small capable handheld radios that are suitable for a coat pocket or even the smallest boat. A cellular phone is an adjunct, not a replacement for a VHF marine radio.

    What is a VHF Marine Radio? - The VHF radio spectrum runs from about 30 to 300 MHz (megahertz). A few uses of the band include television, FM radio, public safety and nautical radio transmissions. VHF marine radios are channelized, each pair of frequencies (transmit and receive) used by the radio are assigned a number. The operator doesn't enter a frequency like 158.600 MHZ to call the Coast Guard. Permanently mounted radios have a maximum output of 25 watts, while handhelds typically stop at 5 watts. VHF radio waves propagate in what is termed line of sight, they will not bend over the curve of the earth or around or large terrain features. Depending on the power output, condition of the radio and antenna; the effective range of a VHF radio is from 5 to 30 miles.

    Marine VHF Channels - Each channel on a marine VHF radio is assigned to a particular use. The most important one is channel 16, which is the hailing and distress channel. Some congested areas will use an alternative hailing channel. Boaters should monitor channel 16 when not using their radio on another channel. VHF marine radios also receive forecasts and warnings broadcast by the National Weather Service. There will be a selector switch or menu item labeled US/International on your radio. Keep it on the US position while operating in the United States.

    Basic Channel Allocations - These are just a few of the 104 channels available for mariners:

    • Channel 6 - Intership safety communications
    • Channel 9 - Communications between vessels. This channel is also used in some areas by the Coast Guard as a hailing channel
    • Channel 13 - Navigational safety communications
    • Channel 16 - Distress and hailing communications
    • Channel 22 - Communications between the Coast Guard and the boating public. This channel is used by the Coast Guard to broadcast weather and warning messages
    • Channels 68, 69, 71, 72 and 78 are used as working channels for recreational boats and communications with shore based stations. There are other channels available for particular geographic areas

    Hailing Another Boat

    - To contact another vessel, you need to hail it on channel 16 (or 9 in some areas). Channel 16 is used for hailing and distress calling, so don't interfere with these calls. Key the microphone, giving the name or location of the boat you wish to contact. Typically boaters will call the name three times. Keep the message short and if there is no response, wait a while before trying again. If contact is made, negotiate switching to a working channel to finish the conversation.

    Distress Calls

    - In the event of a extreme or life threatening emergency, use channel 16 and make a MAYDAY call. A delay or running out of fuel isn't an emergency. Learn to use your radio prior to needing it during an emergency. Most radios have two available power settings, one (1) or twenty-five (25) watts. The low power setting is for communications with nearby vessels. Use the higher setting for an emergency call.

    Coast Guard Recommended Emergency Radio Call Procedures:

    • Ensure the radio is on
    • Select channel 16
    • Press the microphone transmit button
    • Clearly say: MAYDAY MAYDAY MAYDAY
    • After calling MAYDAY, give your vessel name, location, nature of emergency and number of people on board
    • Release the transmit button
    • Wait for 10 seconds - if no response is heard, repeat your MAYDAY call
    • Make sure everyone onboard is wearing a life jacket

    Rescue 21 - The U.S. Coast Guard is in the midst of what they call the National Distress and Response System Modernization Program (NDRSMP) to replace their current communications system. Shorthand for NDRSMP is Rescue 21. Once new radio components are installed in Coast Guard facilities and aboard assets like cutters and helicopters, several new technologies will be adopted. A few noteworthy features are direction finding accurate to 2 degrees, interoperability of radios between agencies, implementation of digital selective calling (DSC), and the ability to monitor multiple channels simultaneously. Once infrastructure is in place, DSC offers the ability to send automatically formatted distress alerts, receive routine weather or safety calls, and direct dial another DSC equipped radio without having to monitor the speaker.

    Alan J. Sorum

Replies to Article: VHF Marine Radios
  1. Join Date
    Apr 2005

    Default Re: VHF Marine Radios

    That rescue 21 project sounds very interesting. I wonder how far along they are in implementing it.

  2. Join Date
    Mar 2005

    Default Re: VHF Marine Radios

    Great Info.