I'm baffled.
why is it that wreck marks on GPS are so far from the actual position?
do others have this issue? I did a measure between several wreck marks on the GPS chart and the actual mark and the GPS unit marks consistently came up as being more than 0.8nm East and a touch south on the digital chart compared to where to where the wrecks actually are.
very wierd.
anyone else found anomalies where things on the digital chart are no where near the actual position?
I have found the opposite with the HDS10 & Navionics I had researched marks and saved as waypoints and when I got over several wrecks & zoomed in the wreck was marked on chart most times up to 100m away, never really noticed so much on the HDS5, there are a few GPS settings in most units maybe ask Grand Marlin ?Originally Posted by trueblue
I have found some slight variations in locations, some wrecks are perfect yet some are slightly out. I find generally they are out in a NE direction of 100 to 400 meters. I have found this with both garmin and Lowrance units, I suspect some of the translated co-ordinates are out.
Regards
HOnda
Check the datum your GPS is using and the datum your marks were first recorded under, one datum that was popular in yrs gone by is .8nm NE-SE from the current preferred datum.
Jack.
Dunno if mine is right or wrong..... Sometimes it seems bang on and others way off.
When I check the error reading it's 2-3 Metres or suchlike so it's not a bad fix.
My sticky little fingers have got into every menu item possible on my Garmin 551S. So it's entirely possible I have selected a bad datum.... Can anyone advise what should be selected? I am not able to check the options at the moment but I think there were two possible selections.
While we are at it... There are two beacon types it can show (can't remember what they were called) but it doesn't seem to make a difference. What's that about?
How's that for a know-nothing newbie pair of questions!
I just thought it was all simple with WGS 84
have always used that
Mate I have just a got a new HDS 7 gen2 and I was going to post the exact thread this week, I have not been able to find three wrecks that are marked on my GPS, I have structure scanned around the general area with no luck. Might have to wait for a nice calm day and spend a bit more time I guess but its a bit frustrating when you head out all fired up to fish a new wreck hoping its going to be the ducks nuts, then you can't find it.
All the fishos anchoring on it in high winds have dragged it across the bottom?
hey mate, I could be wrong here but if your talking about the wreck marks that are on the navionics charts compared to the actually sounded possition I always thought it was more because when the maps were first created the exact location of the wrecks were not known or might not have had the accuracy to go to decimal degrees. eg 18 22.000 whereas the actual location might be 18 22.265 therefore this will be to the south east of the first mark. This could change as the maps are updated and getting more accurate but up here our maps aren't updated very regularly so they are always out by at least 3-400m except for the known dive sites etc.
Nidrac
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