The positions were accurate during the rest of the 178 nm trip except in that short section of the ICW. My guess is the cartography was inaccurate there.
Dennis C. On Tue, Dec 18, 2018 at 12:34 PM Jerome Tauber via CnC-List < cnc-list@cnc-list.com> wrote: > Is your GPS *set* to output positions using the corrrect *Geodetic* > Datum? Jerry > > > > -----Original Message----- > From: Dennis C. via CnC-List <cnc-list@cnc-list.com> > To: CnClist <CnC-List@cnc-list.com> > Cc: Dennis C. <capt...@gmail.com> > Sent: Tue, Dec 18, 2018 11:22 am > Subject: Stus-List Electronic navigation - chartplotters > > Over the weekend I brought Touche' back home to Mandeville for the > winter. Nice trip but a bit cold for my Southern blood. Here's something > I observed. > > For those who rely exclusively on charplotters and electronic navigation, > here's something you need to look at. Go to Google Earth and enter the > following in the search window: 30°18'2.24"N 87°37'34.10"W > > That will take you to a marshy island in Portage Creek, a portion of the > ICW near Orange Beach, AL. That's where the GPS chartplotter showed the > boat symbol representing Touche' was when Touche' was actually in the > middle of the channel adjacent to island. If I had been using the boat > symbol for navigation and had been steering to keep the symbol mid-channel, > Touche' would have been in the trees on the south bank of the ICW. > > The GPS continued to show Touche' in the trees on the north bank during > the entire transit of this section of the ICW. Having navigated these > waters dozens of times, I'm very familiar with them but a boater transiting > here the first time in heavy fog............................ > > Once out of the man-made ICW the GPS returned to being fairly accurate. > > Just saying, once again, how important it is to use your eyeballs and not > rely on electronics exclusively for navigation. Maybe it doesn't seem like > a big deal when you're in a channel that is well marked but there are lots > of areas with no marks, no land and seriously shallow shoals or rocks. > > Dennis C. > Touche' 35-1 #83 > Mandeville, LA > > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > >
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