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#11800830 - 08/28/16 06:31 AM Gps coordinates and navionics
Bugzout10 Offline
TFF Team Angler

Registered: 06/23/13
Posts: 4326
Loc: Above ground
Trying to load some coordinates on the graph and noticed they're off a considerable amount has anyone else had this problem? I've converted the coordinates in the correct form checked them on google maps and they're correct it's only when I use navionics that they're off

#11800843 - 08/28/16 07:08 AM Re: Gps coordinates and navionics [Re: Bugzout10]
Bandit 53 Offline

Registered: 04/22/11
Posts: 34
You have to choose the proper format in your unit for your waypoints. Most folk use degrees, decimal min or deg min sec.

#11800929 - 08/28/16 08:30 AM Re: Gps coordinates and navionics [Re: Bugzout10]
collincountytx Online   content
TFF Guru

Registered: 04/08/08
Posts: 14279
Loc: Dallas, TX
Double check the original waypoint unit format.

For example:
The Martin's Maps use NAD27 format
Most digital chart plotters use WGS84

The units look identical degrees, minutes, seconds. However, the NAD27 units are calculated by using triangulation from Meades Ranch, Kansas. The WGS84 units are calculated on an ellipsoid grid of the earth from space. Thus, the NAD27 locations can be off by as much as 200 meters compared to WGS84

There are lots of online coordinate conversion calculators

Here's a good link for you

Map Datums

online calculator link
online GPS converter


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