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, 15:32 -0700
From: Lu Abel
Date: 2012 Apr 7, 15:32 -0700
Re NASR (Nautical Almanac Sight Reduction) -- the Power Squadron's two celestial courses (basic, titled Junior Navigation, and advanced, titled Navigation) use Law of Cosines as their principal sight reduction method. But Navigation teaches NASR as a backup and requires a two-sight fix to be reduced and plotted both ways. I guess the theory is that if your scientific calculator is washed overboard you still have a way to reduce sights as long as you still have your Nautical Almanac. Beats HO229 and Ageton that I suffered through 20 years ago.
Speaking of scientific calculators, I don't recall a discussion (especially from the "I wouldn't use a GPS, you can't trust electronics" crowd) as to whether using a scientific calculator to do Law of Cosines is acceptable. To head off the "batteries give out" argument, I'll note that it doesn't necessarily apply to calculators - I have a scientific calculator, bought for $15 many years ago, that is solar powered and claims "if there's enough light to read the display, there's enough light to power the calculator" I've never been able to find a situation where that is not true, even down below at night with a 15w automobile light bulb providing illumination at my nav desk.
From: Frank Reed <FrankReed@HistoricalAtlas.com>
To: NavList@fer3.com
Sent: Saturday, April 7, 2012 3:11 PM
Subject: [NavList] Re: Bowditch sightreduction table (Ageton?)
The 2002 Bowditch, assembled as a complete single file rather than split up into chapters, is available on the NavList web site here: http://fer3.com/arc/imgx/Bowditch-American-Practical-Navigator-2002-(2004).pdfIt's a big file so it takes a while to download. There is a link to this as well as historical editions of Bowditch and many other works of navigation that are available online located here: http://www.fer3.com/arc/navbooks2.htmlBut what sight reduction tables? I didn't see any in the 2002 Bowditch. I don't think there are any in recent editions of Bowditch. Maybe one of the earlier editions linked above? Are you perhaps thinking of the "concise sight reduction tables" included in editions of the Nautical Almanac since 1989? These are not Ageton's table, but they are of a similar short form. They are not popular. I have not met anyone who uses them regularly, even for entertainment, though I have spoken with many people who have tried them out.-FER
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