Reply
 
Thread Tools Display Modes
 
Old 09-07-2016, 07:28 AM   #1
Veteran Member
 
woodscrew's Avatar
 
City: Barnegat Light
Country: USA
Vessel Name: Northern Star
Vessel Model: Bristol 42 1970
Join Date: Feb 2016
Posts: 30
garmin 741xs problems

I put a pair of Garmin 741xs units on my boat this spring while still hauled out. They did not show the proper location by about 100 feet. I figured maybe they needed to move around and get oriented after launch. Not so. They are off by about 80 feet. Recently went up the middle of a long lagoon and my track shows me going over the bulkhead and cruising through several back yards before returning to the water. At the same marina my position
in the slip was off by about 80 feet. I have stopped at fixed markers with the same result. Most annoying is that my $9.95 Navionics app in my iPhone is not only spot on, but has much,much better detail.The 8' wide dock/breakwater at my marina shows up clearly defined. Garmin shows a hairline for the same feature. At a marina I was visiting the Garmin showed no indication of the forty or so finger piers lining the lagoon, while the Navionics had each one with clear definition of it's width.The Garmin has shown me going over land in a local narrow channel every time I go through it. I spoke with Garmin once and am about to get back to them now that I am fully confident that this is not a local mapping glitch as they first suggested. Does anyone else have these issues? By the wayI am a long time Garmin user. The old 498 units that came with the boat did not have these problems. Nor does the 13 year old 276c on my motorcycle and my out board boat. Accurate to 3'. Thanks, Woodscrew
__________________
Advertisement

woodscrew is offline   Reply With Quote
Old 09-07-2016, 10:01 AM   #2
Senior Member
 
Ka_sea_ta's Avatar
 
City: Puget Sound
Country: USA
Vessel Name: Ka_sea_ta
Vessel Model: 48 Defever
Join Date: Jun 2016
Posts: 228
I would make sure you have the latest software update installed. and if you are using the internal GPS ant. ensure that it has an clear view of the sky if not you may have to go to an external ant...
__________________

Ka_sea_ta is offline   Reply With Quote
Old 09-08-2016, 04:10 PM   #3
Veteran Member
 
woodscrew's Avatar
 
City: Barnegat Light
Country: USA
Vessel Name: Northern Star
Vessel Model: Bristol 42 1970
Join Date: Feb 2016
Posts: 30
I have an external antenna mounted on the flybridge. Signal strength is excellent and accuracy is 8.7'. Garmin support walked me through the steps to check both. They are sending me an SD card with the latest mapping updates on it.Hopefully it will cure the problems. Thanks.
woodscrew is offline   Reply With Quote
Old 09-09-2016, 06:07 AM   #4
Guru
 
CaptTom's Avatar
 
City: Southern Maine
Country: USA
Vessel Name: Cygnus
Vessel Model: Prairie 36 Coastal Cruiser
Join Date: Dec 2012
Posts: 1,218
This is a long shot, but it used to be common for folks to inadvertently select a geodetic datum other than WGS84. That would give you the symptoms you're seeing. I'm not sure on the 741, but on the 740 it can be selected by:

1. From the Home screen, select Configure > Units.
2. Complete an action:
• Select Position Format to set the position format in which a given location reading appears, and select a position format.
• Select Map Datum to set the coordinate system on which the map is structured, and select a coordinate system.

I've "fixed" this setting on a number of boats, but I think nowadays all chartplotters default to WGS84. I know the Garmin 740 does. Still, we all tinker with our electronics when we're first learning how to use them, and sometimes we change things without realizing it.

I've also seen us steaming across land on several different chartplotters. But only where I know the underlying cartography is the problem, such as on canals in the US and Canada. Where there are NOAA charts, this should be very rare.
CaptTom is offline   Reply With Quote
Old 09-12-2016, 09:26 AM   #5
Veteran Member
 
woodscrew's Avatar
 
City: Barnegat Light
Country: USA
Vessel Name: Northern Star
Vessel Model: Bristol 42 1970
Join Date: Feb 2016
Posts: 30
If the updates don't fix it I'll try that next. Thanks.
woodscrew is offline   Reply With Quote
Old 09-12-2016, 09:35 AM   #6
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 2,723
I like the wrong-datum theory. It would explain everything.
__________________
www.MVTanglewood.com
twistedtree is online now   Reply With Quote
Old 09-14-2016, 01:01 PM   #7
Guru
 
Pgitug's Avatar
 
City: Punta Gorda, fl
Country: Usa
Vessel Name: Escapade
Vessel Model: Nordic Tug 37 2002
Join Date: Jan 2015
Posts: 783
Quote:
Originally Posted by twistedtree View Post
I like the wrong-datum theory. It would explain everything.

+1
Pgitug is offline   Reply With Quote
Old 10-31-2016, 08:46 PM   #8
Veteran Member
 
woodscrew's Avatar
 
City: Barnegat Light
Country: USA
Vessel Name: Northern Star
Vessel Model: Bristol 42 1970
Join Date: Feb 2016
Posts: 30
update.......not

So the latest Garmin update has been installed by my very knowledgable electronics guy with no change in the 80 foot position error. And we went two blocks away to look at a friend's much bigger Garmin unit (I forget the number) and he has the same error exactly. I really think this is a cartography issue. I also really think you should not have f**k with these things. Will call Garmin this week and see what kind of bull they throw at me this time. Oh yes I didn't tell you their response to the lack of detail in various marinas and lagoons as compared to my Navionics/Iphone app. We don't want you staring at the unit while in close like that- you should be looking out the windshield. Good advice in daylight. Not so much in darkness and fog. What BS. Very disappointing.Will keep you posted.
woodscrew is offline   Reply With Quote
Old 10-31-2016, 09:10 PM   #9
Guru
 
BruceK's Avatar
 
Join Date: Oct 2011
Posts: 6,901
Interesting experience woodscrew. Garmin`s USA office was very helpful when I wrote them about incorrect advice from Garmin Aust, on the basis of which I had bought their products, which could not do what they said they would. Compounded by them later being unable/refusing help to fix my problem,or theirs, until I contacted head office. Good luck with your issues. I found the conflicting advice from different staffers a real problem. Hope you get it resolved.
__________________

__________________
BruceK
Island Gypsy 36 Europa "Doriana"
Sydney Australia
BruceK is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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





All times are GMT -5. The time now is 08:13 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012