Have a question about Marine Radios? Check out these FAQ's!!!
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What is a Marine Radio?
A marine radio can be an indispensable addition for uses such as:
Is a license required to use a marine radio?
What is the range of a marine radios?
What is DSC?
What kind of messages do Marine radios with DSC may send?
What is an MMSI number?
How can I get an MMSI number?
Can I operate two VHF radios at the same time, using one antenna?
With today's cell phone technology, why do I still need a VHF radio?
Can I mount the antenna beside the radio?
Do I need a ground plane for a VHF antenna?
What range can I expect from the antenna?
What is the receiving zone for my antenna?
What is JIS7 submersible rating mean?
My radio turns off every time I transmit on high power.
Aren't VHF radios complicated?
Should I buy a hand-held or a mounted VHF radio?
What if I need help?
What if I just want to contact a fellow boater?
What is a Marine Radio?
Through international agreements, a band of frequencies has been reserved strictly for marine use. These frequencies fall within the range of 156 to 162 megahertz.
These channels are strictly for marine use, either ship-to-ship or ship-to-shore. They should never be used for land communications. A total of 83 channels are available, some of which are reserved for special purposes (government, Coast Guard, or commercial use). Having special channels just for boats helps to ensure that there will not be too much interference with other types of communications.
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A marine radio can be an indispensable addition for uses such as:
- To enhance safety afloat
- Communicating to other boaters
- Navigational aid
- Obtaining weather or navigational information
- If you need assistance
In addition, the U.S. Coast Guard monitors the marine channels to aid boats in distress. Marine radios are allowed to use higher power levels than other types of non-licensed radios, which helps to ensure that you will be able to communicate. Cell phones and low-powered radios may not work reliably at the distances sometimes encountered when boating.
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Is a license required to use a marine radio?
A license is not required for recreational use in the USA. Use in other countries may require a license.
However, most new VHF radios will come with a license application. You can also contact your regional FCC office for the application. Many marine stores and dealers also carry this application.
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What is the range of a marine radios?
This is difficult to answer, because range will be affected by the following factors:
- Transmit power: Higher transmit power gets better range. Transmit powers up to 25 watts are allowed.
- Length of the antenna: Besides transmit power, this is typically the most important factor that affects range. The longer the antenna, the better the range.
- Height of the antenna: The higher the antenna is mounted, the better the range. Antenna tuning: Having a properly tuned antenna will maximize your range. Checking the SWR of the antenna will identify how well your antenna is tuned to the marine band.
- Atmospheric conditions: Atmospheric conditions can affect radio propagation. If conditions are just right, there are times when you can transmit 100 miles or more. On other occasions you may be limited to only 10 miles. These extremes occur infrequently, but do illustrate the effects of atmsopheric conditions.
- Your location: Your location will also influence the range. For example if you are located on an inland waterway where buildings and trees can block your signal, you will get less range than if you where in the middle of the ocean. With a handheld radio your range will vary depending on whether you are inside the cabin (worst range) or standing on the highest portion of the deck (best range).
- The combination and severity of the above factors will determine your range. Several of these factors can change on a day-to-day basis. If we were to eliminate all the negative effects, a properly setup mobile radio transmitting 25 watts will communicate as follows:
- A powerboat communicating to another powerboat: approximately 20 miles.
- A powerboat communicating to a well-equipped shore station: approximately 50 miles.
- On a sailboat with the antenna mounted at the top of the mast, communicating to another sailboat: approximately 40 miles.
- On a sailboat with the antenna mounted at the top of the mast, communicating to a well-equipped shore station: approximately 80 miles.
A 5 watt handheld will communicate approximately 7 miles to another handheld, or approximately 20 miles to a well-equipped shore station.
A 2 watt handheld will communicate approximately 5 miles to another handheld, or approximately 15 miles to a well-equipped shore station.
Please remember, your mileage may vary... : )
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What is DSC?
Digital Selective Calling (DSC) is a feature that lets you send digital messages. Using DSC, a marine radio can send an automatic distress signal at the push of a button. If you have a GPS receiver connected to your marine radio, then the distress call will also contain your GPS coordinates.
DSC can also be used to send a message to a group or to a particular boat (the other boats must have a DSC radio).
Channel 70 is reserved for DSC messages. All DSC messages are always sent on channel 70.
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What kind of messages do Marine radios with DSC may send?
- Distress signal
- Send a call signal to an individual boater
- Send a call signal to a particular group of boaters
- Send a call signal to all boaters
- Request the position of a particular boater
- Send your position to a particular boater
ADDITIONAL DIGITAL SELECTIVE CALLING INFORMATION
For additional information the USCG has an excellent site that should be visited at United States Coast Guard
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What is an MMSI number?
An MMSI number (Maritime Mobile Service Identity number) is a special number which identifies your vessel. After obtaining an MMSI number from a government-approved issuing agency, you then program it into your marine radio. When you send DSC messages, your MMSI number will be added to the message. This is especially useful if you send an automated distress message. It makes it easier for rescue craft to identify your vessel.
All DSC-capable radios must have an MMSI number before the DSC features will work.
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How can I get an MMSI number?
MMSI numbers can be obtained from numerous issuing agencies. Here are several choices:
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Can I operate two VHF radios at the same time, using one antenna?
No. A coaxial switch must be used if you want to run two radios off the same antenna.
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With today's cell phone technology, why do I still need a VHF radio?
Cell phone tower coverage is very directional and does not travel offshore very far. Remember, all VHF radios also receive NOAA weather broadcasts. It is also a requirement to keep your VHF radio on and tuned to the local calling channel when on the water to monitor any emergencies.
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Can I mount the antenna beside the radio?
No, it must be at least three feet away from the radio, so transmission will not interfere with the radios reception (usually resulting in a squeal in the speaker).
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Do I need a ground plane for a VHF antenna?
Not necessarily, most VHF and CB Marine Band antennas are designed with independent ground planes built in. Check with the manufacturer of the radio you are planning on buying.
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What range can I expect from the antenna?
To determine the range of an antenna, multiply the square root of its height (In feet) above water by 1.42. This gives the range in miles.
Remember to perform the calculation for BOTH vessels, then add the results to get the range between two vessels.
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What is the receiving zone for my antenna?
For most VHF Marine antennas the receiving zone is 360 degrees - or omni-directional. Check with the manufacturer to be sure.
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What is JIS7 submersible rating mean?
JIS stands for Japanese Industrial Standards. Level 7 is a submersible rating. The radio can withstand being submersed for 30 minutes. We all know that if this actually happens, you have bigger problems than your VHF, but the main jest of this test is to make sure the radio can withstand being mounted on a VERY wet boat.
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My radio turns off every time I transmit on high power.
First have the antenna tested for a high SWR, or temporarily connect the radio to another VHF antenna that is working properly to verify the problem. If the antenna is working properly make sure the unit is connected directly to a solid 12V source, or connect directly to the ships 12V battery.
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Aren't VHF radios complicated?
No, but you do need to learn some basics. Here's an overview:
- If you have a VHF radio, you must monitor channel 16 while you're on the water. Channel 16 is the International Distress and Calling frequency. It is used for distress and urgency traffic, for safety calls and contacting other stations. You can use it to make contact with another station (boat), then move to a non-emergency frequency such as 68 or 69.
- Channel 22 is used by the Coast Guard for announcements on fishery closures, inclement weather or other notices.
- Channel 9 is a calling and reply channel for recreational vessels.
- Use the one-watt setting except in an emergency.
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Should I buy a hand-held or a mounted VHF radio?
This depends on where and how you boat. Hand-helds are less expensive and portable from boat to boat. They will serve the more casual boater well. However, they don't have the range or power of the built-in radios, their batteries don't last as long and, because they can be dropped, are more prone to damage. Mounted radios have better range because, generally, the antenna is longer and they have up to 25 watts of power. They're wired to the boat's battery so can transmit as long as the boat battery is operational. They do require installation and take up dashboard space. An ideal combination is a mounted VHF radio with a hand-held as a back-up.
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What if I need help?
If you are in a life threatening situation:
- Have all persons put on life jackets!
- Make sure the radio is on and it's on Channel 16.
- Press/Hold the trasnmit button.
- Speak slowly and clearly, saying: MAYDAY, MAYDAY, MAYDAY
- Give the following information: Vessel Name and/or description; Nature of emergency; position and/or location; number of people aboard.
- Release the Transmit Button.
- Wait for 10 seconds. If no response, repeat "MAYDAY" call again.
- If not in immediate danger, follow the same steps as above, except do not use the word "MAYDAY."
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What if I just want to contact a fellow boater?
Here's an example:
- Call the vessel on channel 9 or 16 in the following manner.
- Name the station being called, speaking it three times.
- Say "This is" and name your vessel or call sign.
- Say "Over."
- Wait for the station being called to answer. The answer should be made in the same manner as your call.
- When answered, ask the station to move to a working channel.
- Say "Over."
- Wait for a reply, then switch to the working channel.
Here's another example call:
- Calling station: "Coho One, Coho One, Coho One, This is motor vessel Salmon Man OR 760 ZD, Over.
- Responding station: "Salmon Man, Salmon Man, Salmon Man, this is Coho One, OR 82 XY, Over.
- Calling station: "Please switch and listen channel 68, over."
- Responding station: "Switching channel 68, over."
- You then switch to channel 68 and call Coho One using the same procedure. All conversations should be kept short and to the point.
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