Where am I?? Funny problems with poor cartography.

[labatt]

All this discussion about GPS issues, celestial fixes and chartplotters made me recall this picture we took during our recent trip... Anyone else have any funny pictures of poor cartography?

[Boasun]

I've had this happen to me here in Louisiana. I'm in the center of the bayou and the GPS has me a hundred yards on the beach.
Plus you can't update the electronic charts either. A nasty liability that is going to burn some of these companies that provide those charts. So the buoys and sometimes the land mass are different on the ecdis and the paper charts.
Belle Pass (Port of Fourchon) is one of them. the ECDIS is about twenty or more years out of date in displaying the port.

[SailorMitch]

C-Map updates their charts every year -- for a price of course.

[sailingdog]

Originally Posted by Boasun

I've had this happen to me here in Louisiana. I'm in the center of the bayou and the GPS has me a hundred yards on the beach.
Plus you can't update the electronic charts either. A nasty liability that is going to burn some of these companies that provide those charts. So the buoys and sometimes the land mass are different on the ecdis and the paper charts.
Belle Pass (Port of Fourchon) is one of them. the ECDIS is about twenty or more years out of date in displaying the port.

That is why Garmin and some of the other manufacturers have a nasty disclaimer at the powerup of their units.

[Sapperwhite]

Labatt,
Thanks for the screenshot. that was exactly the type of thing I had mentioned in a previous post and caught some guff over it. I have yet to experience that sort of offset myself, but i know better than to put all of my eggs into one basket. Sure GPS makes life easy, but we have to look up around us too. Thanks again, i feel sort of vindicated now.

[trantor12020]

I suppose their disclaimer says "... electronic charts not meant for navigation use"

[camaraderie]

Sapperwhite.. that was exactly the type of thing I had mentioned in a previous post and caught some guff over it.
That's cause this is a chartplotter NOT a GPS. GPS's are accurate.
Actually..that is probably about 50 yards off the canal. Not great but not bad either...it's not like some REAL charting errors that are off by a 1/2 mile or more.

[sailingdog]

Actually, while GPS's are generally accurate, but not always... even when they are accurate, they may not be accurate to the paper charts... since the paper charts, like those in the chartplotter, are only as accurate as the tools used to make them. Also, the chart datum of the charts may not be the same as that of the GPS, and if you're using two different chart datums—one in the GPS and one from the chart—you're introducing a fairly significant source of error.

This type of error is not uncommon when the displays are "overzoomed" on a map segment. I can't tell from the screen shot if this is the case in this instance or not. My Garmin unit gives a warning indication that the image has been over zoomed....Might be worth a look.

[sailaway21]

Experience the same thing with my GPS in my work truck about a couple of times a month. I forget which thread I discoursed on the matter, probably long-windedly, but the point is, or should be, that GPS is an offshore/over the horizon navigation tool. It is not appropriate, nor is any electronic navigation equipment with the exception of radar, in a piloting situation. Use of it on those situations calls for an ample supply of Lloyd's Open Form on hand.(g)