NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Horizontal Sextant angles plot.
From: George Huxtable
Date: 2010 Nov 29, 21:02 -0000
From: George Huxtable
Date: 2010 Nov 29, 21:02 -0000
Byron wrote- "My luck was with me, I was reading a magazine to my daughter and I noted a statement and a drawing stating “an angle from the circumference of a circle is one half the angles to the center of the circle. This gave me an idea that I did not need Fry table, I hoped to show GITMO a new way and gain their confidence and high score for the ship's ability to handle any Navigation situation. Before leaving Rhode Island We trained and tried this new idea. We got underway for our trip to GITMO, At GITMO. The first underway test, we use the bearings and plot on the chart as normal. The instructor stated your” Gyro is down,” We jumped into using the Sextant and the three armed protractor. After several fixes, they stated your three armed protractor is broken we immediately jumped to our new system which was several diagrams on the chart between two sets of NAVAIDS, using a compass with lead I scribed circles that intersected for our position as we move out the harbor. They had never seen this before with the new design that I had placed on the harbor chart, they stopped the exercise and inspected and asked questions about the design on the chart, and gave us an outstanding grade... " Byron seems to be describing the geometry for constructing a position circle through a pair of landmarks with a known included angle between them. He deserves credit for working that out from first principles, back in 1969. But around that same time, at a yachtsman's navigation evening-class in Britain, I was being taught the same technique, and it is detailed in Cotter's "Elements of Navigation" of 1953, and likely many other texts of earlier date. So it's a surprise to me that such a well-known procedure, on this side of the Atlantic, appeared so novel to the top navigational brass of the US Navy. George. contact George Huxtable, at george@hux.me.uk or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.