# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Distance Measurement - Tape vs Google
Date: 2013 Apr 11, 23:29 -0400

http://fer3.com/arc/m2.aspx/Dipmeter-again-LaPook-apr-2012-g18850

On Apr 11, 2013 11:26 PM, "Bruce J. Pennino" <bpennino.ce@charter.net> wrote:

Hi:

My intent was to show everyone and myself that Google Maps Distance Calculator is just excellent for all distances starting at even 100 ft or 200 ft. The precision/accuracy increases so that at 500, 1000 ft or more vertical angular measurements achieve very reasonable precision with devices other than a theodolite.

With a channel width of over 500 ft, I'm still curious to reconcile the HoE difference of 22.5 ft and 15 ft.  Which is the more correct value?  I believe that was in Gary's posting....but now I'm unsure of which message. Sorry, sometimes I lose track of the original message in a discussion..

Bruce

----- Original Message -----
Sent: Thursday, April 11, 2013 9:05 PM
Subject: [NavList] Re: Distance Measurement - Tape vs Google

Hi Bruce

Gary LaPook wanted a very long baseline with the bubble sextant measured angle to improve the accuracy of his HoE, in his "Dip Meter Again" post. I think that's one of the reasons why he did it that way, using Google earth.

You can use a lesser distance because of the greater angular precision of your theodolite. Hence the 200' restriction of your tape isn't a restriction! Nicely done.

The bubble sextant, of course, cannot really compete with a theodolite for angular measure and thus HoE determination at a distance of 200'. Note that a larger population of bubble sextant owners are in the audience than theodolite owners. So for the benefit of those who have one and not the other, using a long baseline helps when determining HoE by bubble sextant.

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