A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Lars Bergman
Date: 2017 Jan 26, 09:01 -0800
Robin Stuart asked:
"Is it reasonable to expect that it would have been standard practice for Worsley to record a DR position every day at around 15:40 GMT?"
My answer is no, the DR position was intended to show the position at local apparent noon, not at a specific GMT. When 24 hours is mentioned, I think it was noted only to show that the given course and distance was the last "day's run", not the sum of several days.
Furthermore, Robin asked: "Would it be normal practice to record an EP advanced to 15:40 GMT in this way?"
My answer is no. The latitude obtained from the noon sight was "moved backwards" to be used in the calculation of the am time sight. The longitude obtained from the time sight was then "moved forward" to the time of noon. On some days the course and distance sailed (estimated) between the time of am sight and noon is shown. The underlined position below the DR position is usually the observed position.
A few years ago I had some email discussions with Brad and produced a document with some of my findings. I have now made an update of the document and maybe it can bring some light into the transcript of Worsley's navigational log. I believe that every number in the log could be explained, he probably didn't write down unnecessary information.
Lars 59N 18E