GPS accuracy

[Jon Hacking]

Oh, yes, when you zoom OpenCPN way in, it produces a yellow shadow around your track. That's probably what you're seeing. Hadn't realized you were zoomed in that far...

[Snowpetrel]

(Edit, saw BCN was way ahead of me... ) Try turning off highlight tracks in the settings under the ships tab.

Sent from my HTC_0PCV2 using Cruisers Sailing Forum mobile app

[phiggins]

Found a program that comes with the GPS that gives info about it. I used it to turn on WAAS. Will do another run to see how it looks. The circle is the same size. The circle does not appear with tracking disabled.

[Stu Jackson]

WADR, who cares?

If anyone actually believes that GPS accuracy to 3 meters is important, then one must consider re-learning basic navigation 101.

GPS is a VERY, VERY good guide. Emphasis on GUIDE.

I recommend going back to the suggestion on page one and re-reading Calder's How to Read a Chart book or any other GPS guide on accuracy expectations.

[phiggins]

Yes I guess its the circle around the track. If I turn off track highlighting it disappears. This what it looks like now after a few hours with WAAS on and also I changed the OpenCPN Tracking Precision from low to high so it shows most of the track points.

Well Stu I think a lot of sailors would like to know how accurate their instruments are, but as you say it still should be just a guide.

[Stu Jackson]

Originally Posted by phiggins

Well Stu I think a lot of sailors would like to know how accurate their instruments are, but as you say it still should be just a guide.

Paul,

When I first got my old Magellan Blazer 10 or 12 GPS, no charts, I watched it change the lat/lon every few seconds.

When I got my Garmin GPSMap 76 Cx maybe ten years ago, I watched my "location" jump around when I was in my slip. Gee, it still does! I did exactly what you're doing, by zooming way into "overzoom" on the chart.

What it taught me was never to use the GPS to get back to my slip in a complete whiteout.

They are just NOT that accurate, nor were they ever intended to be.

If you read a tad of history, for example, the old Loran C systems were actually much better at repeat-ability to get BACK to the same point than are old &/or more modern WAAS enabled GPSs.

Too many people think that, because of electronics, precision is enhanced. Nothing could be further from the truth for many reasons, reasons that folks have written entire books about.

That''s all I'm trying to say and it is the basics for navigation of ANY sort.

Also covered in the manual for your own GPS whatever it may be.

Continued Good Luck.

[barnakiel]

The gps skips the beat once and the two circles overlap giving an illusion of an ovalish shape.

b.

[phiggins]

Yeah who really needs a GPS, be like Captain Ron...

Just kidding Stu.

[HappySeagull]

doesn't answer your original question but per monitoring your gps, Try "Visual GPS". My favourite. Has lots of info.

VisualGPS, LLC

you want VisualGPSView
http://visualgps.net/VisualGPSView/default.htm
or VisualGPS
http://visualgps.net/VisualGPS/default.htm
which is the one I am using for a long while

[Stu Jackson]

Originally Posted by phiggins

Yeah who really needs a GPS, be like Captain Ron...

Just kidding Stu.

Ah, my favorite! Thanks for remembering, Kitty!

[HappySeagull]

anyways, you can turn off "Tracking Highlight" in the toolbox and then the "issue" goes away. (If I don't understand it- I look for which wires to cut.Saves Brain Pain

[colemj]

Originally Posted by Stu Jackson

Too many people think that, because of electronics, precision is enhanced.

It is enhanced. Try taking 10 sextant shots or 10 DR's and see what your precision is.

The problem is that people confuse accuracy with precision.

Mark

[transmitterdan]

What method of determining speed and position has greater accuracy than GPS?

[Alan Mighty]

Originally Posted by transmitterdan

What method of determining speed and position has greater accuracy than GPS?

For starters:

1. GNSS, or Global Navigation Satellite System, using several sat-nav systems such as the US GPS signals, the Russian Glonass signals, China's BeiDou signal, Japan's QZSS signal, etc etc.

2. GNSS coupled with ground-referenced signals. For example, Yanmar has tested in Australia (and Japan, Taiwan, and the Philippines) its agricultural machinery using Japan's QZSS signals and a local ground-referenced signal. Yanmar reported that its agricultural machinery (tilling soil etc) had horizontal in-accuracy of few centimetres.


3. Land surveying equipment has for several years now used GNSS receivers, some (but not all) with ground-referenced signal reception, with much lower horizontal inaccuracy. Of course that gear is much more expensive than the gear available to recreational sailors. Next time you see a surveyor team, go chat and ask them for a Captain Cook at their gear.

Al

[Stu Jackson]

Originally Posted by colemj

The problem is that people confuse accuracy with precision.

Mark

Well put, thanks, that's where I was going with the thought.