Navionics app accuracy
Submitted by bradz on Thu, 2015-01-01 20:24
Was out North of Rotto this morning. I had plotted a lump on the Navionics app on my phone. However, it was not there. This is not a small lump, it just wasn't there. Checked my Lowrance hds7 gps....also not there.
this happened last year up at Jurien on the hds7.
Has anybody else experienced that? I a using the gold card in the hds7.
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I did then the best that I knew how. When I knew better, I did better.
fincher
Posts: 150
Date Joined: 23/10/12
Yes have had the same even
Yes have had the same even using the navionics web app it shows lots off lumps I particular fish yet on the phone there no were to be seen and even on my hds7touch running gold maps it shows no lumps at all so not sure wats going on there
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Percula
Posts: 273
Date Joined: 23/09/08
So on app but not on chart plotter?
So are you saying there are no lumps there on the sounder and on the GPS in the boat?
bradz
Posts: 693
Date Joined: 29/10/07
app
The app and the GPS say there is a lump, but when I drive over it, there is nothing on the sounder.
Also, when I say a lump, I'm talking about a depth chance of around 6m.
I did then the best that I knew how. When I knew better, I did better.
southcity104
Posts: 1659
Date Joined: 27/01/09
navionics is very inacurate.
c-plot, c-map and a few others are far more reliable. I had a go of the platinum fish n chip 3d function on the lowrance with navionics and was unimpressed.
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eziliving
Posts: 875
Date Joined: 30/12/09
Yep have had the same
Yep have had the same problem before. Have also found the lump can be a couple hundred metres away.
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bradz
Posts: 693
Date Joined: 29/10/07
Ok
Well that's just bloody fantastic isn't it.
I did then the best that I knew how. When I knew better, I did better.
keg
Posts: 398
Date Joined: 17/07/07
i always thought
that gps is a military thing,they have the power to block it and change it`s accuracy and also depends on how good a satellite signal your are recieving,my gps tells me the accuracy on any given day and it varys from a few metres to hundreds of metres.it`s worth sounding around a fairly large area looking for the ground.
keg
Posts: 398
Date Joined: 17/07/07
double post
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carnarvonite
Posts: 8667
Date Joined: 24/07/07
Charts
Its not so much the accuracy of the GPS but how good are the charts they use. There are quite a few lumps marked on paper charts that are not shown or can be found on electronic charts and vice versa.
I know when they swapped GPS systems years ago one would find that if the spot wasn't there you would start searching approx. 100 metres to the NE from the mark.
Rob H
Posts: 5796
Date Joined: 18/01/12
Johns correct of course, have
Johns correct of course, have to remember that the purpose of the charts is for navigation not fishing, and with Navionics its likely you don't have access to the large scale charts. Being "layered" you aren't told which you are viewing either.
There are many areas that haven't been surveyed for decades including some off 80mile beach that were still 1800's (may have been updated now).
Areas like the Abrolhos will have a pinnacle marked with minimum depth but takes some time inside the marked area to actually find as the smallish scale only needs to show a ship where it must clear safely.
If you look on a paper chart you can see when the data was recorded in the lower corner.
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