NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Range by height beyond the horizon
From: Frank Reed
Date: 2009 Nov 16, 14:29 -0800
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? -FER --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com -~----------~----~----~----~------~----~------~--~---