T&T: GPS, Chart, Mistakes ?

[LA Licata]

Be careful with this "calibration" technique.

It appears not to have a linear effect all the time as one moves the  
boat.

I for one used it to accurately set my position in the slip when I  
boated in Chicago. (Raytheon Plotter...CMap charts, DGPS and not WAAS)

Went north toward the Mackinaw Straits and while passing under the  
bridge, the plotter was way off. Remembered about the calibration and  
took it out. Plotter was dead on.

Remembered reading that others had experienced the same thing so, I  
lived with the fact that it showed me one slip off when I got home.  
Do not know too much else, but also remember that if one shifts the  
chart reference in the plotter, and one has calibrated the unit, all  
bets are off on where the plotter will put you.

So, I think I would use calibration if I was staying close to one  
place all the time, and check it for accuracy if I travel some 30+ nm  
away from "home." But, finding that may be more "work" than I want, I  
just might never use it at all.
Lee


Date: Fri, 31 Aug 2007 09:28:04 -0700
From: "Cameron King" <camking at earthlink.net>
Subject: Re: T&T: GPS, Chart, Mistakes ?

...My Furuno 1850 chart plotter/GPS requires calibration...