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Old 08-11-2005, 19:33   #1
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gps antenna

Hello all, My question is, where is the best place to mount my gps antenna, I figuered that I would mount it on the top of my mien mast. Then I relized that means going alloft when things break. Do I really need to put it up that high? I would gess it would stay out of the weather the most there and have a open shot at the satalights.
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Old 08-11-2005, 19:45   #2
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hi kingfish, it shouldn't make a difference. Height is only important for terrestrial receivers. As long as you've got unobstructed line of sight to the sky you'll be fine.

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Old 08-11-2005, 19:57   #3
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Most places near deck level should be fine, as long as it has a clear view of the sky. You do not want to put it up high. The motion at the mast top can cause false readings of the boat's speed and heading as it pitches around.
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Old 08-11-2005, 20:27   #4
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Right-on Exposure!

You often see GPS antennas mounted, with some difficulty, on top of radar domes, and on top of almost anything indicating an ignorance of just what is needed. You made the proper points!
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Old 09-11-2005, 01:37   #5
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As stated, Mast top, NO!
Close to a Radar isn't the best either.
Anywhere a clear view of the sky can be obtained. In saying that, I have mine inside the Pilot house. It looks through a hatch and the perspex does not seem to hinder it. I have the Main Boom directly above and this has not been an issue either. The one test I haven't had yet, is a wet sail directly above. A large wet area like the sail can sometimes cause difficulty.
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Old 09-11-2005, 03:10   #6
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Wheels, mine is mounted in a similar position, and have had very wet sail above it with no problems - I really like a wheelhouse when its raining!
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Old 09-11-2005, 14:35   #7
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Thank you all, you just saved me allot of work! I am still trying to figure out the electronics. Id rather use the sextant anyway. But getting a sight in rough seas is easyier with a screen to look at.
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Old 09-11-2005, 15:44   #8
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In the coaming

Mine's inset in the cockpit coaming, aft quarter. In the picture you can see it just under the blue line. I've got an arch and a bimini and never a problem with reception.
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Old 09-11-2005, 16:55   #9
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Usually on the stern rail, or T-top, depending on your boat. All are correct in having clear view to sky, but also out of the way so guests don't grab it when they are looking for a hand hold.

Vasco - you're just showing off that nice boat. Don't blame you.

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Old 09-11-2005, 17:49   #10
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Vasco’s comment about mounting the GPS antenna ”... out of the way so guests don't grab it when they are looking for a hand hold ...” reminds me of an old rule of thumb:

If it looks, or is placed like a handhold, it will be used as one. All such equipment must be built like a handhold, or moved.

The classic example is the flimsy aluminum Bimini or Dodger frame. It looks like a handhold, and is located where you might want a handhold - but it isn’t capable of performing as a handhold. Since they’re not practical to relocate, Bimini/Dodger frames have to be built very strong, like a handhold.

I too, mounted my remote GPS antenna on the stern pushpit rail (just uncomfortably out of reach from the transom boarding ladder). Worked fine, despite possible “shading” due to Bimini.
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Old 09-11-2005, 18:08   #11
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Capt. Lar,

I was very surprised when the dealer mounted the antenna where they did. I'm used to mounting them on the stern rail somewhere, usually too close to the ladder so you always have to warn people boarding not to grab it. The spot on Breathless works very well. Newer antennas seem to be fairly impervious to what were thought of as obstructions. I have seen a lot of hand-helds working well down below at the nav station. Mine appears to be obstructed and the bimini is often wet yet it works fine. Talking about showing off when are we going to see your newly painted boat?
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Old 09-11-2005, 18:13   #12
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I have two.

One is mounted on the pushpit and the other is below on the nav station. They both give the same results. It is only a radio wave and will transmit through the fiberglass deck. The only appreciable difference is the time it takes to initialize. The one in the cabin takes a minute longer to locate all the satellites it needs to lock on, but some of that time I attribute to the fact that it is 7-8 years old and the antenna is only 3/4" X 3/4".
GPS antennae should be located as close to the water as practical to reduce movement. At the top of the mast, in a seaway, the antenna will be all over the place and constantly pointing in opposing directions.
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Old 09-11-2005, 18:28   #13
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Vasco - I flush mounted the receiver in my center console on my flats boat, no bracket. Yours is the first I have seen installed this way on sail. Removing the bracket eliminates grabbing and fouling problems. Very cool. I have to say, when I see the newer boats set up, there are a lot of details that are just right. Those of us that have to retro have a harder time getting it to look as clean.

Jim - I am surprised to read your post. You should have a harder time holding satellites. My back-up hand held GPS often looses signal down below, but is always up in the cockpit.

As to paint and varnish - they just laugh at me. Brush guys are worse than woodworkers. Repair and primer is complete. Awlgrip stern is next. Varnish will take some time - I am putting it right and since most on this forum gave me little support for other methods, I opened the wallet. I will reinstall chock after varnish. Wanted to seal wood first. Then its just running rigging and wait.

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