NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Bowditch sightreduction table (Ageton?)
From: Lu Abel
Date: 2012 Apr 7, 17:12 -0700
From: Lu Abel
Date: 2012 Apr 7, 17:12 -0700
Re slide rules: You need five or six-place accuracy in LOC calculations to get a reasonable Hc and the commonplace that all of engineers (of sufficient age, at least) learned on were accurate to about 2-1/2 places. This list has discussed rules such as the Bygrave that appears to have much more accuracy. My view, though, is that slide rules, while useful for almost all engineering calculations (anybody want even a 1% margin of error on safety calculations?), celestial requires calculations 1000 more times accurate. High-precision slide rules might offer one solution, but there are others, eg, the various sight reduction tables that have been published over the ages.
Let's not forget that before WW II, "calculator" meant a person who did
calculations, not a machine (mechanical or electronic) for doing them. So I suspect that many of our older sight reduction tables were produced by a roomful of "calculators" tediously working out a five- or six-place solution to just one entry in the table.
From: Alan S <alan202@verizon.net>
To: NavList@fer3.com
Sent: Saturday, April 7, 2012 4:38 PM
Subject: [NavList] Re: Bowditch sightreduction table (Ageton?)
Re Power Squadron courses, I started the Nav. course, having previously done Jr. Nav.The Nav course required reduction of sights and the plotting thereof, as I recall, using both Law of Cosines and the Nautical Almanac Tables. Again, as I recall, I have the plots and calculations around somewhere, I ended up with approximately the same calculated fixes, though it did seem to me that the so-called Concise Tables are a pain to use.They do work though, one of these days, I will give the Ageton Tables a try, and see where it is that I park the aircraft carrier. Seems to me that the Law of Cosines is the easiest to work with, asasuming the presence of an eldctronic calculator.While it might be dooable, I would not attempt to run LOC calculations with a slide rule, especially given how clumsy I am with one.Alan
----------------------------------------------------------------
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
----------------------------------------------------------------
