NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: That darned old cocked hat
From: George Huxtable
Date: 2010 Dec 9, 13:28 -0000
From: George Huxtable
Date: 2010 Dec 9, 13:28 -0000
Reading John Karl's attached document "That darned old cocked hat", I am surprised by his second result, that "the probability that the ship is outside the cocked hat is 84%" That differs from the conclusion previously aired, at some length, on this list and elsewhere, that if there were no systematic error so that the remaining random error made an intercept towards or away equally likely, the chance of a vessel being outside the cocked-hat would be exactly 75%. The logic leading to that conclusion appears to be unshakeable. If asked, I will go over it once again. In addition, I've convinced myself of its truth by a computer simulation, for what that's worth. So John's figure of 84% throws his other conclusions into some doubt, in my eyes. Is he prepared to argue why it should differ from 75%?. George contact George Huxtable, at george{at}hux.me.uk or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. ----- Original Message ----- From: "John Karl"To: Sent: Wednesday, December 08, 2010 10:22 PM Subject: [NavList] That darned old cocked hat That darned old cocked hat seem to keep popping up. I’ve given this some thought lately and have computed some examples to investigate questions -- such as where the point of maximum probability is. I’ve thought for a long time, and still do, that this is all perhaps rather interesting academically, but of no practical importance for a navigator who is only interested in the safety of the ship. In that case you’re never sure where you are better than the known random-error distances from each LOP. (Ocean racing or armed combat might have different objectives.) The linked PDF file gives my results and observations. I’d be glad to run off other examples if anyone is interested. JK ---------------------------------------------------------------- NavList message boards and member settings: www.fer3.com/NavList Members may optionally receive posts by email. To cancel email delivery, send a message to NoMail[at]fer3.com ----------------------------------------------------------------