NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Thoughts on Celestial.
From: John Huth
Date: 2012 Nov 3, 12:06 -0400
From: John Huth
Date: 2012 Nov 3, 12:06 -0400
Yes, I've been using that formula for square root of eye height in feet x 1.1 = miles to horizon. I teach that to my students, and variants for visible range.
For closer in range, I use the 'rule of thumb' of 100 feet at 1 mile subtends 1 degree. I also know that my index finger at the end of my outstretched hand is about 1.3 degrees. This is helpful when I kayak in coastal waters to estimate my distance to a landmark, like a lighthouse.
Sometimes, I'll use a single line of position (e.g. bearing to the lighthouse) and then use the above trick to get a range, and use that combination to get my position.
It's good to have a number of "go-to" options, as it depends on the situation. I try to practice a lot of these as a matter of habit while either backpacking or kayaking, just to stay tuned up and see how they work in different circumstances.
On Fri, Nov 2, 2012 at 12:35 PM, Byron Franklin <byronink@netzero.com> wrote:
Byron: to john H and other hikers. The triangle using the magnetic compass can be reduced by using the Franklin Piloting technique even using mountains and charted hills. If the variation is not large or if unknown,It will help with the position. Another thing that is good to know is table 8 bowditch, Height of the eye above the horizon. It is only the idea that can be used, because you have no real horizon. If you are on a hight hill an estimation of you height
above your horizon will give some idea to how far your horizon and other objects are. Square root of eye height X 1.1 to horizon. Give it a try let me know if usefull. It is very usefull at sea.
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