antenna placement

thereheis · Post by **thereheis** » Apr 17th, '07, 21:43

has anyone tryed placing there gps antenna inside the cabin overhead ? was thinking about doing it to keep the outside of the boat a little less cluttered of stuff,,was wonderin if it would get a good siginal being up there?right now the boat is inside a big meatal building so i cannot test it ?any info on it ???

phil

In Memory Walter K · Post by **In Memory Walter K** » Apr 17th, '07, 23:15

My experience is that a signal will be received under canvas or fiberglass but not under metal. If the fiberglass is thick, it might get degraded. Most GPS antennas are small and innocuous enough. Placed under the swept back windshield of my B-20 has worked for me also. Walter

JP Dalik · Post by **JP Dalik** » Apr 18th, '07, 00:10

GO FOR IT!!!!!!!

We mounted the gps dome as far forward on the centerline support beam as possible. We have 2 sensors and instead of cluttering up the top I mounted one inside. Both units receive the same number of sat's at the same signal strength.

I have seen the big boats mounting gps receivers in the far forward corners of the flybridge for years. If you have an XM or Sirius receiver don't be afraid to mount them in that location either.

I wouldn't mount a gps sensor any lower, I tried putting a back up unit in an anchor locker in a center console to keep the hard top clean and found the when running in a big sea we consitently lost signal from wave height blocking the signal. You do need to keep the sensor up high (sometimes difficult in these low riders)

bob lico · Post by **bob lico** » Apr 18th, '07, 00:55

jp what about the hollow area in the flybridge under the anchor light indention under the glass on a mount?

Craig Mac · Post by **Craig Mac** » Apr 18th, '07, 08:54

i mounted mine same as JP----on the centerline support of headliner as far foward as possible---no issues with reception---i only have a bimini top--not sure if a hard top would create any problem.

Capt. DQ · Post by **Capt. DQ** » Apr 18th, '07, 09:40

I would like to mount mine Garmin as JP & Craig Mac was talking, but was worried about the full marlin tower and with the radar running if it would interfering with the GPS signal in rough weather or sea.

DQ

JP Dalik · Post by **JP Dalik** » Apr 18th, '07, 10:16

Give it a try. You can place the sensor anywhere and let it lock in. Try it in a few spots. The Raymarine piece we had worked mounted high on the fiberglass tub under the helm area.
The Northstar sensor is a 2 piece and I was able to get it mounted on the center support beam well forward of everything else.

In Memory of Vicroy · Post by **In Memory of Vicroy** » Apr 18th, '07, 11:48

I have three GPS antennas mounted close together in a fore & aft line on the port top of my fb hardtop. The one for the Garmin 2010C is in the middle. I've noticed that when the radar (Raytheon 41X 4' open array) is running, the Garmin will lose signal now & then. The other two antennas next to it will not. It only seems to happen in rough weather, so I'm not sure if the radar antenna is blocking the signal to the Garmin or if the radar waves are interfering. I'm been meaning to raise the Garmin antenna a couple of feet so it will be above the plane of the radar, but not gotten around to it yet.

UV

randall · Post by **randall** » Apr 18th, '07, 12:32

i might be mistaken but seems to me patrick put the GPS antenna in the flybridge on "buddy boy"

John Jackson · Post by **John Jackson** » Apr 18th, '07, 14:38

I put mine on top of the "wedge" on the front of the flybridge where the light used to go. It works perfectly there.

Sean B · Post by **Sean B** » Apr 18th, '07, 14:54

I've noticed that when the radar (Raytheon 41X 4' open array) is running, the Garmin will lose signal now & then. The other two antennas next to it will not.

Vic I had the same problem with my Garmin, that the radar messed it up sometimes. The antenna they sent was a "GPS 17." I noticed that they had a newer model antenna out so I bought it, installed it, and the problems went away. I think the new one was a "17HVS", and was around $200. Kind of sucks they didn't send that one with my unit, but it's over now. You might want to try that. I kept both antennas on the boat and wired in a switch, so in case one gets fried I'll have a backup antenna to use.

In Memory of Vicroy · Post by **In Memory of Vicroy** » Apr 18th, '07, 16:33

Sean - thanks, good info. Since it only does it in rough, stormy weather, that's when you need both the radar & plotter, so gotta fix it bye & bye. I'll call Bobby at Sea Trac and see what he can do. What kind of switch did you use? Coax? or just a single pole?

UV

Sean B · Post by **Sean B** » Apr 18th, '07, 22:41

Well there are four wires for the antenna, two for power & ground, and the other two are for talking to the plotter. I kept the power lines hot all the time to both antennas, with the power coming from the Garmin wiring harness, spliced to both antennas. I called Garmin and asked before I got into all this, and they didn't know for sure because apparently nobody asked them about wiring in two antennas to the same unit before, but I finally reached a guy that was thoughtful and said I could switch the two data wires. But he was also sure that I should not have two antennas talking to the unit at once.

I found a little black plastic switch that slides at Radio Shack ("you have questions, we have blank stares") that would switch two wires at once, either one set of two are on or the other set of two are on, with a total of six contacts on the back, and I installed that. It was surgical soldering and I melted the first switch and had to go back to the store, so if you do this do yourself a favor and buy two when you're there. It's definitely not a marine grade switch either but I put it below the bridge dash where it will stay reasonably dry. And some guy told me about this oily stuff you can spray on switches... can't remember the name... to keep them working. So far so good after two years

MikeD@Lightningshack · Post by **MikeD@Lightningshack** » Apr 22nd, '07, 11:05

Do you carry a spare switch, my bet is that if something has a likelihood of failing, it is probably the contacts in the switch, will you lose both units if there is a failure at the switch? Or were you able to wire it in such away that that can't happen.

I'm thinking that maybe it would make as much sense to just put a spare unit and cable in a parts box on the LightningShack. If the tranducer goes belly up, I'd just plug the new one in, and set it on helm for the ride home.

Of course I have very easy access to the back of my GPS units, which isn't always the case.

Just a thought,

In Memory of Vicroy · Post by **In Memory of Vicroy** » Apr 22nd, '07, 21:43

Sean - thanks. The switch type is called a Double Pole, Double Throw (DPDT) and is commonly available from the good toggle switch makers like Culter-Hammer. The plastic ones are suspect but if kept shot with CX and dry they are OK. I'll call Bobby at Sea Trac tomorrow about the new sensor.

UV

JP Dalik · Post by **JP Dalik** » Apr 23rd, '07, 00:48

UV,
Gps sensor domes should work as well as counter parts as long as it is above or below the beam of the radar. If its in the radars transmit path forget it, be happy any of them work at all. (We had a 25Kw unit that we had to block out the aft 25 degrees because it would wipe out the sat phone and tv, kinda kept you lookin back to make sure you weren't gettin snuck up on).
If it is the center piece in the scheme, sometimes these are shadowed by nav lights flags or the radar itself. I would check to see if when you are locked up that it has the same number of sat's as its counter parts and are received at equal volumes. You might have a shadow you didn't think of. Bottom line is sometimes these things go bad. If its more than 6 years old and doesn't show the same as the others, I'd think about a new dome.
Good Luck

Sean B · Post by **Sean B** » Apr 23rd, '07, 12:13

Guess I should re-think that little black switch from Radio Sh!t... add that to the ever-growing list... but the regular CX treatments should keep it healthy until I get to it.

Haven't seen a single spot of rust on the engines since joining the CX club, or anything else I've used it on for that matter

Brewster Minton · Post by **Brewster Minton** » Apr 23rd, '07, 12:40

I had to move my sat phone attenna from the radars sweep too.

bertram31.com

antenna placement

antenna placement

just a thought,

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