NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Bubble sextant intervention needed.
From: Paul Dolkas
Date: 2012 Oct 18, 23:23 -0700
From: Paul Dolkas
Date: 2012 Oct 18, 23:23 -0700
Geoffrey- Well I'm not, really - but I was always taught that you need to leave a sextant out to equilibrate with the outside temp before taking a sighting. I have noticed that when I neglect to do this on hot days I get really scattered results - which makes sense, since part of it is hot and part cold, so the alignment is bound to suffer. Once it equilibrates, it really doesn't seem to affect the accuracy, albeit with a smaller bubble size. Sometimes though it gets hot enough so that the bubble shrinks to less than the solar disk, which makes getting an accurate sighting pretty difficult. Maybe I just need to make a nice white quilted sextant cozy, and get the best of both worlds... -Paul -----Original Message----- From: navlist-bounce@fer3.com [mailto:navlist-bounce@fer3.com] On Behalf Of Geoffrey Kolbe Sent: Thursday, October 18, 2012 10:39 PM To: NavList@fer3.com Subject: [NavList] Re: Bubble sextant intervention needed. Paul, I have a stupid question too. Why are you leaving your A-12 out in the midday sun? When using my A-12 out in the Sahara desert, I did not notice any change in bubble size. But the sextant (octant) lived in its box, a yellow foam lined Peli case, when it was not actually being used for taking sights. Perhaps you just need to paint its box white ;-) Regards Geoffrey
