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Old 01-21-2012, 06:42 AM   #1
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Duel mount for GPS antennas??

I have two garmins, one upper and one lower helm and a A60 Raymarine at the upper helm. Upper helm not a hard top so have to mount "stuff" on the bridge structure. Curtains preclude use of pipe structure. *Do they make a duel antenna mount of some sort or should I cobble up one from schedule 40 PVC?. Will those antennas co-esist without interferance with each other. How far away from the VHF antenna do I have to keep them?

The one existing antenna is mounted on a short extension at the side of the bridge and loses siganal now an than. Intend to go two feet extension vice the 1 foot like the existing antenna and go on the opposite side. Thanks
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Old 01-21-2012, 08:57 AM   #2
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RE: Duel mount for GPS antennas??

I have two GPS antennas mounted on a PVC pipe "spreader" about 12" long. The antennas are in the top of the middle of the flybridge forward face. The spreader has a tee in the middle which screws onto the adjustable angle antenna mount on the flybridge. The antennas of course screw onto the male/slip fittings on the uprights of the spreader. I have had no interferance at all with the setup and no outages even though they are under the brow and windscreen by almost a foot.

I did not glue the male/slip fittings on the spreader, they just sit up there and can be slipped off if I need to replace the antenna or do maintenance. They look much better if you paint the PVC pipe spreader prior to installing it. Poof can white works well. It has a shine and matches the boat close enough. I have my third GPS antenna mounted on the side of the flybridge about 1 foot from the CB antenna. I've noticed no interferance from that either, but I seldom use the CB so it's possible there is some.

Ken
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Old 01-21-2012, 09:00 AM   #3
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RE: Duel mount for GPS antennas??

Ray

I have about the same bridge structure as you, all fiberglass, and I*glassed*wood mounting pads to the inside*face of the flybridge under the dash.* Port side, as all my dash electrical, horns*and VHF were*more from the center to*the starboard side.**No problems, full signal and tracks all 8 Sats. plus both WAAS Sats.* At those frequencies GPS signal will*pass through glass very easily.

Larry B
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Old 01-21-2012, 10:16 AM   #4
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RE: Duel mount for GPS antennas??

GPS antennas don't interfere with one another*as they are passive...I think the prefered distance is a meter from a VHF antenna and definitely out of the RADAR beam.

Last I looked, Raymarine and/or Shakespeare web sites had antenna location recommendation diagrams.
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Old 01-21-2012, 05:12 PM   #5
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RE: Duel mount for GPS antennas??

Great idea to put them topside vice on the side. I tested and have much better signal--18 feet accuracy vice 40 and I don't have to drill a lot more holes in the side of the bridge. I'll take my side mount back and get a spreader mount. Thanks
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Old 01-21-2012, 06:32 PM   #6
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RE: Duel mount for GPS antennas??

We bit the bullet and had an alminum mast fabricated last year for the radome, anchor light, GPS antenna and weather station antenna. The latter two are almost the same dimensions so kind of relate to your question.

All up the mast cost $710 in Campbell River BC.

In the photo the WS is to starboard and the GPS to port; it is strongly recommended to cover the WS when not in use so we did that, and of course had to cover the GPS for balance!
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Old 01-22-2012, 08:39 AM   #7
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RE: Duel mount for GPS antennas??

Quote:
psneeld wrote:


GPS antennas don't interfere with one another*as they are passive...I think the prefered distance is a meter from a VHF antenna and definitely out of the RADAR beam.

Last I looked, Raymarine and/or Shakespeare web sites had antenna location recommendation diagrams.


I kinda agree. A lot of them have voltage being fed to them for an internal receive amplifier.

That being said, I have installed hundreds of them on everything from cop cars and two way radio sites within a foot or two of each other.. Sme of the larger cell sites have upwards of 20 GPS antennas within a small radius.
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Old 01-22-2012, 09:41 AM   #8
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Duel mount for GPS antennas??

A GPS antenna does not have to be mounted on a mast to work. Signals will penetrate figerglass and wood just fine. I tested mine before installing it. I get full strength on the maximum number of satellites.

It's under the flybridge*helm and that's a Garmin mount made for the purpose.



-- Edited by rwidman on Sunday 22nd of January 2012 10:42:05 AM


-- Edited by rwidman on Sunday 22nd of January 2012 10:43:45 AM
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Old 01-22-2012, 10:28 AM   #9
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RE: Duel mount for GPS antennas??

I'm with you on that one.* Much cleaner look having them out of sight, plus you're not advertising what electronics you have on board to the boat prowlers cruising the docks looking for easy targets.* Same goes for outboards and other high value items left on board when you're gone.* Keep them out of sight!!

Larry B.*
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Old 01-22-2012, 11:30 AM   #10
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RE: Duel mount for GPS antennas??

How do you hide an outboard in a convenient place?
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Old 01-22-2012, 11:56 AM   #11
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Duel mount for GPS antennas??

Boating friend of mine bought a new Nordic Tug last year had*owned it for maybe three months.* The new*outboard*was*locked to an onboard*storage mount.**His marina is guarded, gated and no guest moorage, so it is assumed they came in*a skiff at night, cut the lock*and took the motor.* Nobody saw them and no other boat was touched.**They knew what they wanted in advance and came in and out very quickly.* Last I heard they hadn't recovered it.

Just as important as locking it up, is keeping it out of sight from curious eyes.

LB


-- Edited by Edelweiss on Sunday 22nd of January 2012 01:59:13 PM
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Old 01-22-2012, 01:30 PM   #12
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Duel mount for GPS antennas??

Quote:
Edelweiss wrote:
I'm with you on that one.* Much cleaner look having them out of sight, plus you're not advertising what electronics you have on board to the boat prowlers cruising the docks looking for easy targets.* Same goes for outboards and other high value items left on board when you're gone.* Keep them out of sight!!

Larry B.*

My TV antenna is on the other side, under the helm.* It works fine there.* The only problem is, the picture is upside down!

*

OK, just kidding, it works fine.

*
*


-- Edited by rwidman on Sunday 22nd of January 2012 02:32:28 PM
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Old 01-22-2012, 07:02 PM   #13
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RE: Duel mount for GPS antennas??

Got the two antennas mounted on one rail mount today. Just used a screw on PVC T to the rail mount and put the antennas on each end. Great reception topside and out of sight when curtains on. Not very obvious with the curtains off. Thanks for the suggestion.
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