A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Paul Dolkas
Date: 2015 Nov 8, 20:49 -0800
This is the classical technique. It was used because it allows the (mechanical) chronometer to run uninterrupted; a necessity for keeping it operating accurately. With digital watches, of course, this all becomes a non-issue. You can easily design the watch to remember the instant you press the “now” button. Alas, digital watches became popular just about the time CN was being replaced by radio & satellite navigation. I’m sure that if the quartz watch had been around during the 30’s & 40’s, the “classic” navigation chronometers would have all had this feature.
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Marty Lyons
Sent: Sunday, November 08, 2015 3:27 PM
Subject: [NavList] Re: Use of stopwatch taking sights, any other users?
I use a slightly different technique. I have a mechanical stopwatch on a lanyard around my neck. I also wear a digital quartz watch on my wrist set to UTC. While taking a sight I hold the stopwatch in the hand operating the drum micrometer. At the time of coincidence, I start the stopwatch. I then leisurely place the sextant on a safe place. I then observe the quartz wristwatch and at any even minute of UTC, I stop the mechanical stopwatch. I record the time of the even UTC minute from the wristwatch and the stopwatch interval from the time of sight to the even minute. I then proceed to take a few more sights. Later I subtract the intervals from the even minutes to get my actual UTC time of sights. Usually my interval in putting the sextant down to the next even minute, ranges from 15 seconds to 2 minutes. You must remember to reset the stopwatch to zero after each shot. In recording the information, I always round up to the next higher second on the stopwatch, to account for my reaction time. So 17.3 seconds is recorded as 18 seconds.