Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 11-09-2017, 11:46   #1
Registered User
 
montenido's Avatar

Join Date: Jun 2010
Location: Lying La Paz, BCS
Boat: 1979 Marshall Californian 42 LRC
Posts: 339
Images: 4
GPS "Dead" Zones?

Hi folks,
I just returned from my first trip to the Isthmus at Catalina, which was great. On the way there my Garmin GPS suddenly lost all satellite contact. It lasted for maybe 15 minutes before coming back online. During that time I checked all connections at the display and antennae, but could find no reason for it. Yesterday, on the way home, I lost satellite contact again in the exact same spot, which is off of Pt. Mugu, where there are heavy military coms. This time it only lasted about a minute or two.

It seems like if it was a bad electrical connection it might do this, with the exception of losing contact in the exact same geographical spot. So, have any of you encountered GPS "Dead" spots before? All comments and opinions are welcomed.

Cheers, Bill
__________________

__________________
M/V Ansedonia
'91 Californian 52 CPMY
Channel Islands, CA
montenido is offline   Reply With Quote
Old 11-09-2017, 12:31   #2
Registered User

Join Date: Apr 2013
Location: So Cal
Boat: Catalina 30
Posts: 942
Re: GPS "Dead" Zones?

There was a FAA notice in June (IIRC) that GPS may be less than reliable in the southwest. Navy testing something.

To know if it's your equipment - use more than one GPS. Your phone is an excellent backup GPS.
__________________

__________________
jeepbluetj is offline   Reply With Quote
Old 11-09-2017, 13:45   #3
Registered User

Join Date: Jan 2008
Location: SF Bay Area (Boat in La Paz)
Boat: Valiant V40
Posts: 430
Re: GPS "Dead" Zones?

Had a similar issue in the Channel Islands. Turned out that my solar panels blocked the built-in antenna on my helm-mounted chart plotter. In my case, simply (temporarily) moving the CP to a spot where the antenna had a good signal was sufficient. Once synched with the satellites, the unit worked fine in its normal position.

I've had a similar problem on rare occasions when the plotter has been powered down for a considerable time, so it takes a long time to find enough satellites for a fix. Again, giving the antenna an unobstructed view helped a lot.
__________________
jamhass is offline   Reply With Quote
Old 11-09-2017, 17:22   #4
Registered User
 
Cormorant's Avatar

Join Date: Jan 2009
Location: Catskill Mountains when not cruising
Boat: 31' homebuilt Michalak-designed Cormorant "Sea Fever"
Posts: 2,062
Re: GPS "Dead" Zones?

There have been some very big solar flares lately, which can interfere with GPS signals. But I don't think they exactly align with the time/date you had trouble. . . .

https://www.engadget.com/2017/09/07/...ommunications/
__________________
Cormorant is offline   Reply With Quote
Old 11-09-2017, 18:18   #5
Senior Cruiser

Cruisers Forum Supporter

Join Date: May 2013
Location: Oregon to Alaska
Boat: Wheeler Shipyard 83' ex USCG
Posts: 1,675
Re: GPS "Dead" Zones?

I have had accuracy issues with gps. I have left the nav programs on at anchor and at my home dock. The tracks generated cover as much as 200 yards. Track is always moving. Sometimes it takes off in a line even further. Much more than the anchor chain and the dock is fixed by pilings. I use TZ Navigator and OpenCPN and have Furuno GPS, a puck gps and a reciever for the European and Russian systems that also reads gps. They all do it. The Euro/Russian is a little worse. I suppose in Alaska, the mountains eliminate some of the satellites. Still much better than Loran or stars on the ocean. Pic is at a dock, open sky.
Attached Thumbnails
Click image for larger version

Name:	GPS track.JPG
Views:	36
Size:	21.6 KB
ID:	155916  
__________________
Lepke is offline   Reply With Quote
Old 11-09-2017, 19:10   #6
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 16,785
Re: GPS "Dead" Zones?

I think it's signal quality or the lack of it anyway.
Usually there is a page where you can view the Sats your tracking and the DOP or EPE, dilution of precision, or estimated position error.

I gave up on Drag Queen as a phone app even though it's great, but my phone would suddenly travel a ways in the middle of the night and set the alarm off, but by the time I got up and checked it, it was accurate again, took a few times for me to figure out what was going on
__________________

__________________
a64pilot is offline   Reply With Quote
Reply

Tags
gps

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
I'll acknowledge the elephant in the room...Full keel is dead... ssb is dead... nematon785 General Sailing Forum 118 23-07-2017 01:31
Magnetic Compass Zones JDGreenlee Navigation 10 17-01-2011 22:53
no wake/low wake zones shellback Rules of the Road, Regulations & Red Tape 39 30-06-2008 17:20
No Discharge Zones engcon Liveaboard's Forum 3 10-01-2007 01:51



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 18:10.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.