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WGS84 vs. NAD83
GPS's are great, aren't they?
My GPS 198C put me right in a slip. When tied up, the only difference was that the GPS indicated I was on the right side when I was centered in a two boat slip. The key is to avoid constant heading/speed changes, so the GPS can keep up with your progress. Quite a confidence builder. But, we'll never be without a paper chart on my boat, and the radar's always on and a lookout posted. Even on nice, sunny days. "Gordon Wedman" wrote in message news:WtoIf.1208$n67.820@edtnps89... "Len Krauss" wrote in message ... Having a little problem with my chart display showing my position approx 150 ft west of actual, I checked chart datum (NOAA BSB raster type) and found it was NAD83, whereas my GPS (non-WAAS) had been set to WGS84. So just for the heck of it I set the GPS to NAD83. That didn't correct the position error. From what I understand, WGS84 and NAD83 are practically identical, so is there any reason not to just leave GPS set to WGS84 (this is in SW Florida, USA)? Any advice on what else to check to correct the westerly error would be appreciated. (using Capn nav software and Garmin GPS 48). Thanks, Len My Garmin 182C with the latest Blue Chip puts my boat exactly where it should be in my marina. Right on the correct finger. I recently bought Ozi Explorer and a friend gave me a set of older charts on CD. With this set-up my boat is 150 yards too far North-East. I thought it might be the datums but no other datum gave better results than WGS4. I bought the latest paper chart for the area and plotted the L/L shown on the laptop. Exactly correct on the new chart. So the old chart on the CD was inaccurate by 150 yards in terms of the location of my marina. I imagine it is more accurate for navigational hazards but it makes you wonder. |
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