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    Range by height beyond the horizon
    From: Frank Reed
    Date: 2009 Nov 16, 14:29 -0800

    Here's a story from USS Growler, the diesel sub formerly armed with nuclear 
    cruise missiles, now a museum ship in New York City:
    "Growler's first deterrent patrol began on 12 March 1960. [...] Lieutenant 
    John J. "Joe" Ekelund, Executive Officer and Navigator, developed an 
    innovative method to determine the submarine's position in the assigned 
    operating area. The technique was quite simple and similar to that used by 
    submarines to determine the range of a target ship. Using navigation charts, 
    Ekelund identified mountain peaks and their height as listed. He then 
    observed the mountain through the periscope and, utilizing the built-in 
    periscope stadimeter, he could superimpose the image of the base of the 
    mountain on its peak. This double image and known peak height provided a good 
    approximate range to the mountain that was read on the stadimeter dial. Using 
    the range so determined, one can could calculate the amount of height which 
    was not seen (was below the horizon) and correct the charted height to the 
    observed height. Using the observable height a second, more accurate range 
    could then be measured. Three iterations of this sequence would yield a 
    navigationally useful range. Using more than one peak, he could accurately 
    determine his position. "
    That should sound familiar! Greg?
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