Next message: Peter Gelinas: "Re: Heading info from GPS (was RE: lv-ab: Heaving-to ... thanks for the input)"
duh, must be a floating slip...
Regards
Laura, Mike and Liz
http://www.seakin.com/gilana/default.htm
>From: Jan Guthrie <>
>To: Mike Brasler <>, live aboard
><>
>Subject: Re: lv-ab: Error in altitude was Re: Heading info from GPS
>Date: Thu, 13 Oct 2005 12:48:51 -0500
>
>Mike,
>If I understand your answer, then the error should be constant.....
>correct?
>Like my slip would always be at the same height or depth from the same
>imaginary sphere. And it is not ... and it can vary wildly from day to day
>and
>even GPS to GPS on the same day.
>
>Jan
>
>Mike Brasler wrote:
>
> > Nope, the error in altitude is the difference between a theoretical
>geoid
> > sphere and the real earth.
> >
> > Our world is not a sphere, not even a flattened one, its kinda bumpy,
>the
> > satellites however orbit at a gravitationally perfect shape, the earth
>is
> > given a theoretical height below the satellites, your altitude is the
> > distance from your antenna to this imaginary shere, its as accurate as
>your
> > horizontal position possibly more so.
> >
>
>
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