Garmin antenna mount: under deck?

sb in gp

sb in gp

Active Member
Oct 10, 2006
858
Grosse Pointe, MI
Boat Info
2016 Tiara 50 Coupe
Engines
Volvo D11 IPS
Well I pulled the trigger and ordered (from Jim) the Garmin 4208 with the XM kit, Sounder and Radar.

In reading the manuals it says the GPS antenna and XM antenna can both be mounted either on the arch or on the underside of the deck.

It would seem that the plus side of mounting under deck would be to extend the life of the antennas because it would keep them out of the weather, it would also keep the arch from getting any more cluttered.

The question is: does mounting under deck affect grabbing and holding a signal for either?

Also, will the Radar affect reception if they are all mounted on the arch?

My instinct is to opt for better reception and mount them on the arch.

Looking for opinion. Thanks.

Scott
 
That might be a misprint. The GPS and XM need a clear view of the sky (they're satellite based). It can work through most canvas, but you also have a windshield frame and an arch to deal with, as well as people. The best thing is on your arch - that's what it's there for. Stick with, what sounds like, your gut feeling.

Ideally, the mount you get for the radar should allow it to be higher than the other antennas.
 
I just bought the Garmin 4210 and it said you can mount it under the deck. A under deck mount bracket comes with the GPS, and I call them and they said on problem. I mounted my GPS antenna on the dash by the window. Works great:smt038
 
Sparkey600 said:
I just bought the Garmin 4210 and it said you can mount it under the deck. A under deck mount bracket comes with the GPS, and I call them and they said on problem. I mounted my GPS antenna on the dash by the window. Works great:smt038
Click to expand...

Those antennas are now strong enough to go through fiberglass?!? Wow. I believe you that you're correctly reporting what Garmin said to you, but I'm still skeptical.
 
When I talk to them thay said under hard top to. The new antenna is called GPS 17X. Does that mean anthing ???????
 
scott, i also installed the 4208 last year w/the gps antenna i installed the antenna on the arch right next to the raystar antenna as the manual said it was ok to do. all the equip. runs perfect i want a clear uninterupted shot to the sky, I dont think the weather would effect the life of the antenna that much.
 
Lazy Daze said:
That might be a misprint. The GPS and XM need a clear view of the sky (they're satellite based). It can work through most canvas, but you also have a windshield frame and an arch to deal with, as well as people. The best thing is on your arch - that's what it's there for. Stick with, what sounds like, your gut feeling.

Ideally, the mount you get for the radar should allow it to be higher than the other antennas.
Click to expand...

Pretty sure it is not a misprint. It says specifically that it can pull a signal through fiberglass, but not metal.

Scott
 
That's what happens when you have a person in China translating the instructions to English.
 
It "might"... I think it would depend on the "deck" it is going under. I have an XM antenna and I know for a fact it doesn't work under my fiberglass hardtop... when I first got it, I was playing around with it and it would cut out if not put in clear view of the sky... My hardtop is two layers thick with the top layer having some core and steel in various places... and it's all about 6-8" thick... so it blocks stuff. If it's just a thin deck, it would probably be OK... but then that will be everyone's favorite place to sit or place a pile of stuff... The fordeck on your boat is pretty thick and is cored... I wouldn't be surprised to see issues. However, under your helm is probably thin fiberglass. What's wrong with the arch?

The sunshine and UV rays seem to penetrate my hardtop just fine though... as I get extremely sunburned being under that thing.
 
Four Suns said:
What's wrong with the arch?
Click to expand...

Nothing wrong with putting it on the arch, except it is getting pretty crowded up there with the TV frisbee, Radar, Light, XM and GPS antenna.

I had a feeling putting it on the arch was the way to go, but I thought I'd confirm before drilling holes.

Any recommendations on placement considering all of the above?

Thanks,

Scott
 
While your GPS may perform to an acceptable level with the antenna mounted below deck, wouldn't you prefer to achieve the best performance possible? Mounting with a clear view of the sky and horizon gives you the best opportunity to have your electronics work as intended.
 
Scott,
I purchased a marine Sirius antenna with the mounts, etc. and my installer asked why? He installed the basic antenna under the hard top and I have not once had a reception problem. I typically just boat in the Great Lakes so perhaps that makes a difference.

I also have a garmin with the same antenna and it came with a special mount to have it under the top as well. I had it installed on the roof because there was already a hole and a bracket mounted but the installer said that he has installed several underneath radar arches and hard tops due to either space issues or people wanting a clean install and not once has he been called back to move them. I would imagine it wouldn't be that difficult to test it.
 
My Garmin is almost 5 yrs old. Don't know much about the new ones but I can tell you it doesn't take much to loose the signal. It's mounted next to the windshield.
 
I can not comment on the GPS antenna but I can on a Sirius, which I am assuming is the same as an XM. My Sirius is mounted inside the hardtop and it works just fine for both radio and weather. If there is metal in the hardtop it will reduce the signal. Since fiberglass is a non conductor radio waves will pass right through it. Any metal will absorb the signal. Hope this helps.
 
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