NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Why do we ocean navigators defer to 249 when 229 isbetter?
From: Lu Abel
Date: 2014 Aug 31, 16:16 -0700
From: Lu Abel
Date: 2014 Aug 31, 16:16 -0700
I believe it is a matter of accuracy -- accuracy of celestial shots vs accuracy of sight reduction -- and convenience.
229 will give accuracy comparable to doing Law of Cosines with a calculator. Might be great for the Titanic, where you had a highly stable platform from which to take shots.
But if you're on a smaller craft that's bouncing around a lot, getting a shot with even a minute's accuracy (much less a tenth) is difficult. So what is the value of a high-precision reduction of a sloppy sight?
On the other hand, 249 gives adequate accuracy with a great deal of convenience and ease.
Let's also not forget the Nautical Almanac's sight reduction method, although I'd characterize that as having the accuracy of 249 with the convenience of 229 -- in other words, perhaps combining the worst of both.
From: Bill B <NoReply_BillB@fer3.com>
To: luabel@ymail.com
Sent: Sunday, August 31, 2014 4:01 PM
Subject: [NavList] Re: Why do we ocean navigators defer to 249 when 229 isbetter?
On 8/31/2014 6:36 PM, Rommel John Miller wrote: > Hi there, it has been awhile and I have been out of touch. But my > question is this: Why are Nautical and Marine Navigators opting to use > HO 249 and shunning HO 229? I like 229 as well. More bodies and better accuracy. Downside is a lot more books to carry. My impression is that 249 is much lighter and may sacrifice some accuracy, but will get you across any ocean or sea with less hassle.
