Uncooperative GPS

[JeffE]

I thought I'd pass on my recent experience with my Garmin 7215.

We spent several days traveling from Elliott Bay Marina, in Seattle, to Princess Louisa Inlet, on the Sunshine Coast, in British Columbia. All went well, and we anchored for two days, right in front of the magnificent Chatterbox Falls. Only ten other boats in the entire inlet...it doesn't get much better than this.

When we left this morning, the Garmin GPS didn't lock onto the satellites. I was annoyed, but the inlet is a fjord, with high walls, and I figured the satellites were just not visible. We exited Malibu Rapids...still no lock. By now, I figured something was wacky. I called another boat, and his GPS started working after he exited the fjord. Hmmmm.

I tried power cycling the 7215. Nope. Tried reset to factory defaults. Nope. Went to the fly bridge and disconnected a wind sensor I'd added to the NMEA bus. Nope. Tried the bridge unit. Nope. Fiddled wires on the mast. Nope.

What finally worked was using the autopilot console to tell the GPS to restore to factory defaults. Now everything worked as usual...except I'd reset the 7215 to factory defaults, so I had to go back and reconfigure it.

Very strange. Rather disconcerting, and not a little aggravating!

So the autopilot console is a surprisingly useful tool.

Jeff

 

[Levitation]

As a general rule, if you are totally dependent upon a fancy electronic device you are going to have problems
Keep a chart in the boat
Get a cheap handheld GPS for back up
In my case my 4212 decided to pack it in while we were in fog and mist leaving Boca Grande
Even the Garmin techs on the phone were not able to resuscitate it
Went across Charlotte Harbor by compass and chart - easy peasy
I now have a back up GPS
Stuff happens

 

[knotflying]

You said you added a wind sensor to the NMEA. Did you reinstall the end terminator to the backbone? Without that reinstalled you could have issues.

 

[SGIDAVE]

Hello Jeff,

You obviously have a fairly complicated, or, at least, extensive N2K network. Next time this issue, or any other presents itself, open the page on your 7215 that shows ALL the network devises. In this last incident, ensure the GPS antenna is actually showing as a devise. If your GPS isn't working and it doesn't show on the network then unhooking/rehooking it may 'cycle' that devise back onto the network. It sounds like it was somehow being excluded. The antennas do 'go bad.' As do the cables connecting them to the network.

Also, ensure your Garmin is up to date on software. Garmin had an update released in June 2015. Oh scratch that, I just checked it was released July 6 2015. That update includes NMEA network updater, etc...
http://www8.garmin.com/support/software/marine.html

My iPad ALWAYS works even when the mighty Garmin craps out. That is, as long as I keep it DRY 😉

dave

 

[JeffE]

All good advice.

Interestingly enough, the GPS did show up in the configuration page. It just didn't want to receive. A firm reset did the trick.

Almost as interesting, is to look at the mast - it looks like there are *two* GPS antennas up there... But only one show up. I'll have to ask the Ranger folks about it.

If you're going to be without a GPS, Jervis Inlet is about the best place you could find...because there's only one way to go!

In this case, I didn't have paper charts, but I did have Navionics on my iPad with the charts. And my phone has a GPS, so this was more of an aggravating mystery, than a real issue. FWIW, the charts on the Garmin aren't very useful in a case like this, because every time you look somewhere other than where the boat "is", the machine going into pan mode, which eliminates the radar and sonar data.


Jeff

 

[Irish Mist]

One of the "pucks" could be for XM radio/ weather for Garmin they look similar

 

[walldog]

One of the "pucks" could be for XM radio/ weather for Garmin they look similar

Both are GPS, the AIS requires separate unit. Why? I do not know.

 

[knotflying]

One of the "pucks" could be for XM radio/ weather for Garmin they look similar

Both are GPS, the AIS requires separate unit. Why? I do not know.

AIS transmit and receive requires the GPS signal to get accurate latitude and longitude information for the transmit function. It also needs a separate VHF antenna for the transmit function as well because it would blow out your VHF radio when transmitting. Basically other than plotting the information on your screen it is a totally independent unit. Hence the need for separate antennas.

 

[walldog]

My AIS on our current boat and on our 27 used separate GPS's, but uses a single VHF antenna. The VHF antenna goes into the AIS 600 first and then to the VHF radio. A coax cable with a PL259 on each end connects from the AIS to the VHF Radio. This is the way the instructions from Garmin show the hook up.

The VHF radio seems to work OK with this set up. I do notice that Ray on Nudibranch, who has been traveling with us up here in Alaska, appears to be able to pick up marginal WX channels in some outlying areas that I cannot receive. So there may be a bit of degradation of signal, at least on receive. (Nudibranch does not have AIS, so his VHF antenna connects directly to his VHF radio.)

Greetings from Sitka