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Re: Noon sight for longitude
From: George Huxtable
Date: 2008 Jul 11, 16:32 +0100
From: George Huxtable
Date: 2008 Jul 11, 16:32 +0100
Andres Ruiz wrote- "The method described in Ocean Navigator is the one in Bowditch current edition." Not quite. That article suggested observing 15 minutes before and after noon. Bowditch suggested a span of 30, either side. There's a big difference in the resulting precision. There's no doubt the method can be got to work, as long as a sufficient span of time is chosen, which depends to a large extent on noon Sun altitude, and on the sea-state for observing. But the longer that time-span, the less appropriate it is to call it a "Noon sight". To preserve that catchy title, those who push this method, which is simply the old one of "equal altitudes", do their best to minimise the necessary length of that interval. Andres' simulation would be interesting when applied to a latititude of say 53�N, with a declination of -23�, when a low noon Sun makes things more difficult.. He added- "Also I try this method aboard a sailboat and the results are acceptable due to the waves and roll and pitch" That's intriguing. It would be interesting to see the numbers he came up with, in real-life; and what he considered acceptable. contact George Huxtable at george@huxtable.u-net.com or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---