Chartplotter

rob1974 · August 20, 2009, 15:45:14 CET

I remember somebody mentioning fishing charts with contours at 10m. I tried looking up throught the search option but did not come across it. Can anyone direct me to that topic or give me further details of these chart?

Rob

guido99 · August 20, 2009, 19:23:54 CET

Garmin G2 charts for compatible garmin units only.

rob1974 · August 21, 2009, 09:56:16 CET

THanks for the reply. I assume they are available for Maltese waters.

Rob

guido99 · August 22, 2009, 00:02:32 CET

Yes !

Moonwalker · August 22, 2009, 00:51:58 CET

Not accurate though

rob1974 · August 24, 2009, 10:39:47 CET

I beleive all chartplotters are inaccurate, thus you have to combine the fishfinder and chartplotter to find the right spots.

Rob

skip · August 24, 2009, 11:29:03 CET

It is annoying, my Navionics Gold Chart is a good 50-75m off in places. Edge up to a beach and it will show you as being on land!

Last time I was trying to find a spot shown on the chart and was no where near, leading me to believe that it could easily be 100m off. Not very handy really and kind of makes you wonder whether these charts are worth it. They're ok for general navigation but not for specific fishing spots, drop offs etc.

The_Gaffer · August 24, 2009, 16:51:02 CET

GPS technology mainly depends on US satellites. The story behind this is that these inacurracies are bulit in to prevent the enemy from homing in onto targets!!!!

I was reading lately that GPS satellites are now past their life expectancy. They are classified in 3 waves, wave 1 is beyond it and soon to be decommisioned, wave 2 is also nearing end of life, and wave 3 has about 2 years to go before running out of power. They depend on solar panels for power, and the panels are running out of life expectancy.

skip · August 24, 2009, 19:01:26 CET

That's true Joe but should be around 5m accuracy, it's the chart overlays that are way off. Deliberate GPS shifts only tend to occur around sensitive areas like for example Sigonella. Clutch Kick can perhaps confirm what happens to his navigation instruments at times when they fly near/around Sigonella Air Base.

rob1974 · August 25, 2009, 09:52:35 CET

Since I do not have my own chartplotter, I am not sure about this. I recall reading somewhere that you can 'calibrate' the chartplotter by either confirming or changing a known spot, say the outer part of Grand Harbour breakwater.

Rob

Moonwalker · August 26, 2009, 01:11:48 CET

Thats interesting rob but near shore I find the charts only shift by few meters while offshore the error is in hundreds of meters.

@Gaffer - I would like to know who is the enemy of a reef 200m underwater? Must be us fisherman

When I contacted the chart ppl at Garmin about this problem they asked to specify coordinates of the shifted spots. Am trying to do this but its not easy to locate the exact spot.

I would like an intelligent chart plotter that updates the chart automatically while reading the bottom. Does it exist?