Moving a GPS antenna

T

Tom on Icarus

New member
I would like to move the puck-like GPS antenna and the anchor light from the front of the cabin roof to the radar arch in order to accommodate our dinghy. As it stands now, they are both in the way. The radar arch is the low one and the dinghy does not fit underneath it so the dinghy must be carried further forward on the roof.

My question is this:

Will the radar interfere with the GPS signal if the GPS antenna is mounted that close to the radome (a foot or two away)? There is also a VHF antenna mounted on the arch. Will it affect the GPS reception?

I appreciate all your feedback. Thanks.

Cheers :beer
Tom
 
Hi Tom,

Our GPS puck is mounted on a stem on the radar arch, just a couple feet from the radar dome... no issue with either. The VHF antenna is on the far side of the arch, away from the GPS puck (radar in the middle).
 
I have heard of radar knocking out GPS pucks. It may or may not be true. (I'm always sceptical of rumors) I'd call the maker and get it from the horses mouth.
 
Tom,

Before you go to the work of relocating and rewiring your GPS puck to the radar arch - try moving the puck to the inside of the cabin (put it near the forward edge of the map shelf). You will probably find that it works just fine in that location and you can easily hold it in place with a small piece of double sided carpet tape).

On my previous boat (C-Dory "Naknek") that was the arrangement. Naknek had radar (no interference), and the GPS signal came through the cabin roof (to the puck antenna...) just fine; with no deteriorated performance that I could determine.

Casey
 
I have a low arch. My Raymarine radar has a 25 degree width of transmission, 12.5 up and down. I used a protractor, looked at the approximate zone, and placed the puck below that on the arch fore and aft brace. No problems with reception.
 
Some GPS pucks are susceptible to interference from marine radar, particularly older Lowrance units. I had one that wouldn't work on the radar arch no matter how high I mounted it. It also would go offline any time I got near the Alaska ferries. I moved to the electronics shelf inside and it worked fine.
 
Tom, I did have an older Lowrance unit that quit working after the puck was mounted in a line with the radar. Whether or not the radar was the reason it died, is unknown. For my current GPS antenna, I have it mounted on a 24" extension, so it is well above the radar.

When you move your light, pick up a second base for the radar arch. They're inexpensive, and that will give you two locations for the light.
 
Thanks for the great feedback folks.
I think I'll try moving the puck inside to the map shelf. Good idea! :D
The other good idea was to install a second base for the anchor light on the radar arch. :idea: That's what I'll do.
Cheers, :beer
Tom
 
Tom, one more idea...

When you pull the wires for your arch mounted light, pull an extra, unused wire and leave it there. That way, if you need to pull another set of wires in the future, you will already have it fished.
 
I had a number of instances, back when I was in the marine electronics business, where a GPS antenna in the line of the radar would quit working when the radar was on. These were Furuno units. Raising the antenna on a 12" to 24" riser would solve the problem.
 
It is pretty well established that some brands of GPS antennas (especially active) are "fried" by Radar. It is not the frequency, but it is the amount of power and the harmonics, which will fry the internal chips on an active antenna.

Do not mount the GPS antenna within the radar beam (figure 15 degrees up and down from the horizontal.
 
Tom,

I moved my GPS puck down off the 24" riser post and down onto the brow, Stbd side and above the color band, to get it out of the way so I could use the riser for a second VHF antenna. Works fine there and it is just the top of the GPS, not the whole teardrop. It is there, forward Stbd corner, but hardly shows up any more. Works fine and is below the radar pattern. I would not set a puck in the radar pattern or close.

Harvey
SleepyC :moon

IMG_2044_sized_1.jpg
 
When I bought my boat I went looking for the antenna for the Garmin MFD... Hunted all over the tower, roof, cabin, etc... Traced every cable I could find, no joy... Finally found it when I took the top off the instrument panel to trace the coaxial cable right from the back of the MFD... It had been tossed in there upside down amongst the coils of wires and loops of coax...

It was working perfectly - so I left it as is... Still working perfectly...
Sometimes the path of least resistance is already going your way...
 
Back
Top