# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Weems article in latest Air&Space Mag
From: Gary LaPook
Date: 2013 Jan 30, 02:05 -0800
The description of how the watch was used is wrong. The watch simply replaces the Nautical Almanac for finding GHA of the sun and the normal computation is done after that, (selecting an assumed longitude so that LHA sun is whole degrees, etc.) to produce an LOP.Flight navigators don't solve for longitude separately as was previously done by surface navigators.

gl

--- On Tue, 1/29/13, Paul Dolkas <paul{at}dolkas.net> wrote:

From: Paul Dolkas <paul{at}dolkas.net>
Subject: [NavList 22163] Re: Re: Re: Re: Re: Weems article in latest Air&Space Mag
To: garylapook---.net
Date: Tuesday, January 29, 2013, 10:02 PM

Gary-

Thanks. I’m trying to recreate exactly how the watch was to be used. In order to get the LHA of the sun, you need to have an accurate watch to do a regular sun shot. Is this what the article was referring to in step 4? I can’t think of any other way to do this.

The other thing I’m a little confused about, is that you would never reset your watch during a flight, unless you had another one on board. (step 4). I would much rather imagine where the hour/minute/second hands would be for the time you want to convert, and then read off the corresponding degrees/arcmin/arcsec.

-Paul

From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Gary LaPook
Sent: Tuesday, January 29, 2013 8:51 PM
To: paul---net
Subject: [NavList 22160] Re: Re: Re: Re: Weems article in latest Air&Space Mag

From which you compute the  LHA of the sun which is a measure of local apparent time (LAT.)

gl

--- On Tue, 1/29/13, Gary LaPook <garylapook---net> wrote:

From: Gary LaPook <garylapook---net>
Subject: [NavList 22159] Re: Re: Re: Weems article in latest Air&Space Mag
To: garylapook---net
Date: Tuesday, January 29, 2013, 8:44 PM

 The classic "time sight" preferably with the sun on the prime vertical.gl--- On Tue, 1/29/13, Paul Dolkas wrote:From: Paul Dolkas Subject: [NavList 22158] Re: Re: Weems article in latest Air&Space MagTo: garylapook---netDate: Tuesday, January 29, 2013, 7:55 PMI found the article fascinating – I never knew Lindbergh was an inventor! The watch is pretty clever, you gotta admit.* Which brings up a (rather basic) question: In the instructions for how the watch was used to find one’s longitude, it talks about finding the local time via sextant. I know of two ways to do this: 1) a noon shot (which isn’t all that accurate, and can only be done once a day), and 2) a lunar. Isn’t there a way of finding local time just using a sun shot? The only way I can think of involves a compass to find the sun’s azimuth. -Paul *OK, I’m a watch guy. From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Dave WaldenSent: Thursday, January 24, 2013 2:38 PMTo: paul---netSubject: [NavList 22100] Re: Weems article in latest Air&Space Mag The Longines Lindbergh Hour Angle Watch www.watchtime.at/archive/wt_2006_06/WT_2006_06_104.pdfThe Weems watchhttp://www.monochrome.nl/the-history-of-the-pilot-watch-part-four-longines-and-lindbergh/----------------------------------------------------------------NavList message boards and member settings: www.fer3.com/NavListMembers may optionally receive posts by email.To cancel email delivery, send a message to NoMail[at]fer3.com----------------------------------------------------------------View and reply to this message: http://fer3.com/arc/m2.aspx?i=122100View and reply to this message: http://fer3.com/arc/m2.aspx?i=122158

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