gps antenna placement

SurryMark · Post by **SurryMark** » Feb 10th, '09, 11:10

I'd appreciate some feedback on mounting an external antenna for a chart plotter. I've seen one at the top of a mast. At Hamilton Marine they said don't do that - put it on the cabin top. In either case, how have people run the cable through the bulkhead or cabin top? I've asked Garmin support, but haven't heard back. I think I'm going to buy a Garmin 4208, with a swing arm for viewing through the companionway.
thx
mark

Ray Garcia · Post by **Ray Garcia** » Feb 10th, '09, 11:35

Why not mount the anntena on the stern rail? You could run the cable through a small hole near the rail using a waterproof plug. You could place it on the port or starboard side depending what side you place the plotter.

Getting the cable into the cabin from the stern area is easy.

Nice choice on the the plotter, impressive.

rg

Joe CD MS 300 · Post by **Joe CD MS 300** » Feb 10th, '09, 12:51

Mark,

The antennas are pretty sensitive so I don't think receiption at any particular location on the outside if the boat would be an issue. I get just about the same reception inside the pilot house with a portable GPS as with the fixed chartplotter antenna on the top of the pilothouse. There is no need for the antenna to be at the mast. The length of the run may actually degrade the signal. Keeping it away from stray lines that could rip it off is much more critical.

Joe

Steve Laume · Post by **Steve Laume** » Feb 10th, '09, 12:55

I went stern rail with a clamp on mount. It was easy with no reception problems, Steve.

king11 · Post by **king11** » Feb 10th, '09, 13:54

I have a Garmin 172, mounted at the helm. I bought an anetnna adapter from Garmin so that the antenna is now built in to the unit. Very compact and no wires to run.

John Martin · Post by **John Martin** » Feb 10th, '09, 14:05

Out chart plotter has a built-in, internal antenna. It is mounted on a swing out arm in the companion way. Works fine, even with the hatch slid closed. Check your unit for internal antenna. Don't mount external antenna unless you need to.

JM

Steve Behnke · Post by **Steve Behnke** » Feb 10th, '09, 15:21

We've mounted ours (older Lawrence) on the stern rail. It's not in the way, works great, and was easy to run wires forward through locker. I've heard that some of these external antenna could really work fine from inside a locker and I've thought about experimenting with that.

SurryMark · Post by **SurryMark** » Feb 10th, '09, 15:27

Thank you, people. No bad advice here.
Steve, the idea of a cockpit locker is intriguing. If that doesn't work I could just continue on the the stern rail.

Again, this is an A-1 site.

Mark

Boyd · Post by **Boyd** » Feb 10th, '09, 16:20

I put mine on the top of the stbd stern dorade box. I ran the wire down the hole and trough the hose that leads into the engine compartment. From there it is an easy feed up the pedistal guard to the Raymarine C70.

Mounting on top of the dorade box is a pretty good guarantee that it wont get stepped on. I considered the cabin top but was afraid of it getting stepped on.

BTW several manufacturers say no to a mast top location. Maybe there is too much motion up there.

Boyd
s/v Tern
CD30 MkII

Jim Davis · Post by **Jim Davis** » Feb 10th, '09, 17:10

I have two Garmins on board. One antenna mounted aft and outside, the other is below in the cabin. The one with the above deck antenna does well. The other will loose signal occasionally when I'm under tree canopy (Dismal Swamp Canal). Some day I will be relocating the antenna.

bottomscraper · Post by **bottomscraper** » Feb 10th, '09, 20:06

Ours is on the stern rail, works great. They need a clear view of the sky but height doesn't make much difference.

Paul D. · Post by **Paul D.** » Feb 10th, '09, 20:46

I repeat that last point that the issue here is a clear view of the sky not height. I attest to that though our years of use of satellite phones. It is simply clear view of sky and then whether there is a satellite in range or not. I would go stern rail. Even though we are putting more and more there squatting our boats down like Bayliners, that would be my choice. It is out of the way yet easy to reach, has a short run and is simple to mount.

Good luck,
Paul

Parfait's Provider · Post by **Parfait's Provider** » Feb 10th, '09, 22:49

Parfait's is on the stern rail, not far from the RADAR pole and I have never noticed a problem. I ran the wires inside the rail and through the deck, but drilling stainless is a pain.

Warren Kaplan · Post by **Warren Kaplan** » Feb 11th, '09, 06:50

I put mine on the stern rail in a position just above where an engine ventilation cowl sits.

I ran the wire down from the antenna down a stanchion, made fast and neat looking to the stanchion with wire ties, and then routed the wire into the cowl, just a couple of inches from the stanchion base.

I then made an itsy bitsy hole in the top side of the ventilation hose below decks and pulled the wire through. Then I routed the wire from there along the inside of the boat to my gps, which is on a swing arm at the companionway hatch.

I put a couple of turns of duct tape around the vent hose where the wire comes through and that was it.

The beauty of this is that I had to drill zero holes anywhere on my boat. Not having to drill a new hole in the deck is always something I will opt for if it is at all feasible.

winthrop fisher · Post by **winthrop fisher** » Feb 12th, '09, 10:24

they don't need to be high just outside,

it does not matter where you put it, just put it any where near the unit.

your making it harder then it is,

mine is on the stern rail out of the way....
winthrop

The Cape Dory Board