Other than the aforementioned channels that automatically select low power we use high power for everything. Never had a problem, never had a complaint.
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Other than the aforementioned channels that automatically select low power we use high power for everything. Never had a problem, never had a complaint.
Moonstruck
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David, I don't think there are any hard and fast rules, but I use low power for anyone within site and harbor communications. Just habit. We very seldom have to lower our antennae so that is not a problem. Just another advantage of no flybridge.
.......... Two "properly functioning" VHF marine radios, on the same frequency, volume level turned up, and within close proximity, line of sight of each other, will hear each other at either low or high power settings.
Unless the squelch is set too high.
The hundreds of islands up here, many of them fairly high, that make long-range VHF communications an iffy to impossible undertaking at best limit our propagation distance automatically. Other than boats in line-of sight range, and there are rarely very many of them at any one time, we almost never encounter communications interference in the San Juan and Gulf Islands and farther north. And using high power is a major help when talking to a boat or marina that's in the "gray" area of poor reception due to the terrain, and of course there is no way to know that in advance.
So we use high power all the time and as a result have been able to reach boats and marinas and harbors when low power would have resulted in no contact.
If boating in more open waters or in areas of dead flat low ground like the ICW appears to be in all the photos I've seen of it, low power could be a big benefit for the reason Edelweiss describes. But using low power here--- and I've tried it a few times--- most of the time simply results in no contact. So we stopped using it almost immediately and simply leave the radio on high power.
We almost never use the radio anyway. We monitor it but we very rarely use it. We only respond to calls from boats we are traveling with or expect to hear from and we almost never have a reason to transmit except to reply to these particular boats or to contact a harbormaster. So it's not like we're blanketing the airways with long-winded descriptions of what we had for dinner the previous evening.
Edelweiss
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The issue of folding the antennae down to horizontal will affect the overall range of the radio at distance, because the marine antennae are usually 3 to 6 db gain. (kind of like the way the light from a lighthouse is focused and projected across the water.) Tip the lighthouse on its side and most of the light goes where???
But it should still work good enough for short range, line of sight, communications, unless the antennae or coax are shorting out.
Larry B.
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ksanders
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The issue of folding the antennae down to horizontal will affect the overall range of the radio at distance, because the marine antennae are usually 3 to 6 db gain. (kind of like the way the light from a lighthouse is focused and projected across the water.) Tip the lighthouse on its side and most of the light goes where???
But it should still work good enough for short range, line of sight, communications, unless the antennae or coax are shorting out.
Larry B.
A horizontal antenna will radiate a signal out from the sides just like if its upright. It does not radiate out the tip at all.
But assuming it's laid down front to back or back to front, there will be little or no signal in front of or behind the boat. And that's probably where you need it if you're passing or being passed.
One would think that a boat owner would know to raise the antenna to a vertical position before attempting to use it. Perhaps the manufacturers should put a warning label on antennas. Like the warning label on coffee cups warning that the contents may be hot.
Contrary to what the specifications might lead one to believe, an antenna does not produce gain. There are no transistors or tubes, what comes out is what goes in. What these antennas do is focus the power fed into the antenna in a horizontal plane (in the case of typical marine VHF antennas oriented vertically). The power that would have been uselessly directed directly skyward and to the bottom of the sea is focused parallel to the water's surface for an apparent gain.
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David, I don't think there are any hard and fast rules, but I use low power for anyone within site and harbor communications. Just habit. We very seldom have to lower our antennae so that is not a problem. Just another advantage of no flybridge.
Don - Now there's a great reason to not have FB!!!
Mark and Eric will like that one...
RickB
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Just for grins, lay your antenna down and do some "radio check" calls on a suitable channel while turning the boat at various angles to the receiving station and let us know what happens. What kind of range at what relative bearings and at high and low power?
Thanks.
That's the "short" answer. Here is more detail:
The West Advisor: VHF Antennas
And for those who do best by looking at pictures (In the computer world we say a picture is worth a kiloword):
Imagine what happens when you lay that antenna down. Where does the signal go?
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markpierce
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Well, I'm "stuck" with a high-for-a-motorboat sailboat antennae. Should normally give good range but with the high hills and mountains around here reception is fairly limited except for the USCG high-strength signals.
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Edelweiss
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Well, I'm "stuck" with a high-for-a-motorboat sailboat antennae. Should normally give good range but with the high hills and mountains around here reception is fairly limited except for the USCG high-strength signals.
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rwidman
Good pic,
(that would be the "lighthouse" analogy, but if you tip a lighthouse over on its side, the light does not come out it's tip.) Now let's hope someone doesn't look at this pic and run out and buy a 9db or greater gain antennae, because they perform poorly on small boats which tend to pitch and role a lot.
Markpierce
You're fine with your antennae, height is good. It should give you excellent service or as good as it's going to get for your area. If you're surrounded by hills and mountains, there is not much you can do about it.
Here in the PNW we're surrounded by hills and mountains too. For my work, that is an advantage as we can string radio base stations and repeaters on top of some high hills 2500 feet plus (I know these would be mountains in some areas, but they're hills here) and serve a large geographic area. Most of our base station sites are running about 50 watts output now and with the FCC mandate to switch to narrow band VHF by Jan. 1, 2013, we'll be lowering that to 25 watts and still cover the same area.
Altitude is king when it comes to VHF propagation. The CG even shares several of our mountaintop sites around the Sound.
Larry B
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Great Laker
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Using low power on the VHF
We are doing the Great Loop and are currently in the interior river system and about to enter the ICW. These are relatively straight paths, much like highways, with high traffic in both directions. There are many boats (both private and commercial), and they are communicating with each other, and with locks, marinas and bridges.
Under these conditions, I believe it makes sense to use the VHF with consideration for others. That includes use of low power whenever possible and limiting "chat" time. Low power is just fine for almost all communications other than those that are long distance or critical or emergency in nature. In fact, some lock masters ask you to reduce power while approaching and operating in the lock.
How often have you wanted a brief conversation on 68 or 72 only to find someone far away smearing the airwaves with mindless jabbering? Let's all be courteous.
We are doing the Great Loop and are currently in the interior river system and about to enter the ICW. These are relatively straight paths, much like highways, with high traffic in both directions. There are many boats (both private and commercial), and they are communicating with each other, and with locks, marinas and bridges.
Under these conditions, I believe it makes sense to use the VHF with consideration for others. That includes use of low power whenever possible and limiting "chat" time. Low power is just fine for almost all communications other than those that are long distance or critical or emergency in nature. In fact, some lock masters ask you to reduce power while approaching and operating in the lock.
How often have you wanted a brief conversation on 68 or 72 only to find someone far away smearing the airwaves with mindless jabbering? Let's all be courteous.
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Pineapple Girl
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Great Laker said:
sooooo true. Good point.
Egregious
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This is correct. How many times have I heard a slow pass radio transaction from 10 miles away? Once you are on another boat's stern you can use low power and not inform every boat within 10 miles that you're passing. On one hand it is nice to know that an extremely polite boater in a sport fisher is approaching, but on the other hand it just blocks up VHF 16.
Just don't chatter on 16 and choose a channel other than what a local marina uses as their working channel and you won't bother anyone. Around here, lots of boats use 17 to arrange slow passes, or just make it short and sweet on 16. The commercial fishermen use 69 and that is a great channel to listen to to see what they are catching, or to hear them bitch about Obama. Entertaining either way.
RickB
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Here is more detail:
Imagine what happens when you lay that antenna down. Where does the signal go?
If the signal only went 100 feet out and 30 feet up that might be a reasonable question but a better representation would show those lobes reaching out for many miles horizontally and quite a few miles upward, not to mention the signal that is reflected off other boats, buildings, hills, and etc.
As far as the lighthouse analogy, if it was a dark and slightly misty night, you would see the glow from a great distance. That is far closer to reality than a focused beam of light in a perfectly clear medium with nothing to reflect or divert any energy away from the beam.
Why not just try it for yourself? Fold your antenna down horizontally and try this - Automated Radio Check Service | Sea Tow
psneeld
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Having a 17-22 foot 9db antenna to me is a good safety issue
Most boats who cruise should have one..they work just fine on most of our trawlers as lond as you aren't rocking and rolling more than 30 degrees regularly.
Most boats who cruise should have one..they work just fine on most of our trawlers as lond as you aren't rocking and rolling more than 30 degrees regularly.
Because I would not have the controlled conditions and test equipment to do a scientific and reliable test.
With the antenna broadside to the SeaTow station, I would probably receive a response and I might (if I didn't know better because of my background and understanding of these things) come to the conclusion that an antenna worked as well horizontally as vertically.
If the antena was pointed directly at or away from the SeaTow station, I would get the results I would expect, no response (unless I was very close to the station).
There's no good reason for a boater to try any tests or experiments when he or she can just follow the manufacturer's instructions. Very few boaters have the expertise the manufacturer has with its own products.
RickB
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Laying down an antenna that already has a tilting base and then doing a "radio check" while pointing the bow in various bearings to the station doesn't really require much "expertise" but then again, no point in busting a good myth .... or maybe proving it.
Regardless of one's background, if the antenna worked just as well horizontally to the station as vertically up to some range, then it works ... no background required. If it doesn't work then at certain bearings it doesn't. Maybe your have just learned a direction finding technique that might come in handy one day ... Isn't anyone interested in knowing or would that ruin the thread?
Regardless of one's background, if the antenna worked just as well horizontally to the station as vertically up to some range, then it works ... no background required. If it doesn't work then at certain bearings it doesn't. Maybe your have just learned a direction finding technique that might come in handy one day ... Isn't anyone interested in knowing or would that ruin the thread?
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Edelweiss
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The manufacture provides theoretical and bench test modeling, which provides average predicted performance. Real world conditions may result in slightly different performance, which is to be expected. There are performance variation from product to product and the environmental conditions of the site install will also cause differences in performance. After we install a new site or move an antenna on the tower, we conduct a field test to determine the real world result.
FM Frequency Modulation - Vertical Polarization (the antenna will perform best when oriented in a vertical position.) That shouldn't be construed to mean it won't work at all in the Horizontal, because they will work, just not as good. We frequently will put up temporary antennae, because of location constraints, in the horizontal and they work fine until we can do a proper site install.
For us boaters using VHF Marine Radios, around 150.x - 162.x MHz frequencies, Range is a product of and limited by elevation (curvature of the earth), limited transmitter power (maintaining a sufficiently high signal-to-noise ratio) and environmental considerations. (mountains, antennae orientation, radio performance, operator skills, etc.)
If you're having performance problems and haven't had your radio checked recently, have a shop take a look at your radio and installation.
p.s. If you swivel your antenna to a horizontal position and it won't work at a short range, like under a mile, then you probably have a broken/ shorted coax cable or corroded/poor connectors. Take it apart and clean connectors, look for cold solder joints at the connectors and replace the cabling if there are any signs of wear.
Larry B
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psneeld
Guru
This post matches most of my theoretical understanding and practical use of VHF.
With digital VHF... line of sight is often exceeded when everything else is correct. On winter nights I often hear Maine to North Carolina USCG stations on CH 16 in southern NJ.
ksanders
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psneeld
Guru
Really can't...just know what marketing calls them on how they process the radio signals/waves (???)(DSC capable???) and that some of the radios and big systems like the USCG's and Sea Tow's definitely improved by a quantum leap in the last 10 years...the reception distances are astounding.
Edelweiss
Guru
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In the simplest form, digital radio is a processed signal which turns sound into patterns of numbers or "digits". The digital receiver converts the digits into audio and sends it to the speaker. Analog signals are radio frequency waves which are transmitted and then picked up by a radio receiver which converts, amplifies and then sends it to the speaker. Digital radios are usually clearer, crisper sounding. But they do have their drawbacks as well.
The current VHF Marine system is an Analog based system. Digital VHF systems are not directly compatible with Analog systems. Although some of the new digital radios can switch back and forth between Analog, Digital and Digital Trunked formats. (Like the new Motorola 7000 series mobile radios. They're also about $7000 each and the portable is $6000.)
Other users of the VHF radio spectrum are being forced by the FCC to switch to APCO P25 compliant narrow band radios in another month. For many of us we're also switching from Analog VHF to Digital VHF trunked radio formats at the same time. Our old analog radios were not P25 capable and had to be replaced anyway.
I am not aware of a digital voice use of the VHF 150.x - 162.x MHz marine frequencies in the US. However, I wouldn't be surprised to see marine VHF FM switching to a digital format sometime in the future. You will have to buy a new digital radio to use the new system and Analog will go the way of Loran.
There is a new add on for VHF radios called DSC (Digital Selective Calling). The US Coast Guard is experimenting with them under a program called "Rescue 21". But it is not a voice calling system here in the US. The DSC device is programmed with your boats preregistered MMSI (Mobil Maritime Station Identifications) number. When you press the emergency button it transmits your GPS Lat/Lon and your MMSI number over Channel 70 on your VHF radio. If you're out of range of a shore station and other DSC equipped boats are between you and the shore station, there DSC will automatically re-transmit your distress call from boat to boat until it eventually reaches the shore station. I hear this is all over Europe now and they have some voice capabilities as well.
Anybody know about DSC??
Larry B,.
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DSC has been around in the US for quite awhile. Six, seven years or more. All marine VHF radios sold new today have it. It's the covered red button on the radio. In addition to the automatic emergency transmission signal that can indlude your lat and long if you feed the radio a GPS position signal (like from a plotter), you can use DSC for initiating radio conversations with other boats that have an MMSI number. The DSC calling feature eliminates the need to establish initial contact on 16 and instead directs both the sending and receiving radios directly to the pre-selected working channel.
The emergency-broadcast-with-position feature is very useful. The "discreet" calling feature is not in my opinion athough some people might find some value in it. We used it a few years ago on a couple of longer cruises in the company of another boat but in the end we simply reverted to making our initial calls on 16 and switching to a working channel.
The emergency-broadcast-with-position feature is very useful. The "discreet" calling feature is not in my opinion athough some people might find some value in it. We used it a few years ago on a couple of longer cruises in the company of another boat but in the end we simply reverted to making our initial calls on 16 and switching to a working channel.
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In mid 1999, the FCC required radio manufacturers to include DSC capability in all new models. This applies to fixed mount radios only, not handheld.
Larry B: Here's a link to a recent bulletin from the USCG on DSC.
Digital Selective Calling
RickB
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The analogue version has been on aircraft since the '60s ... Selcal.
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