NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Paul Dolkas
Date: 2015 Apr 2, 14:42 -0700
Carly-
As a plastic sextant owner myself (Davis 15), I find that the thing warps so quickly when it’s in the sun so that I need to check the index error before a shot and then after & take the average of the two numbers.
Your sextant is white, while mine is black, so I think I would have more of a problem with this than you. You could run an experiment by first checking the error, then letting it sit in the sun for, say 10 minutes, then checking again. I’d be curious about the results regardless of what you find.
Paul Dolkas
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Carly Butler
Sent: Sunday, March 29, 2015 2:57 PM
To: paul@dolkas.net
Subject: [NavList] Re: Art and Navigation
Oh boy - ok, as scary/embarrassing as that idea is Greg, I will dig out my calculations next week and post for you to check (laugh at). : )
On 26 Mar 2015, at 18:28, "Greg Rudzinski" <NoReply_Rudzinski@fer3.com> wrote
Tom,
I agree that trying to keep a sextant's index error exactly at zero is futile but this should not be an excuse for never adjusting the horizon mirror. Carly's Mark 3 without a case will be very demanding on index error stability. I will suggest a plastic food container fitted with customized foam as something to try.
Carly,
If you post all your sight reduction data (a picture of working notes should be good enough) then we can check things out.
Greg Rudzinski
From: Tom Sult
Date: 2015 Mar 25, 11:15 -0700
Carly
The goal is not to zero your sextant, but to know the error. I like my sextant to have several min of error ON the arc. Trying to be exactly zero is hard and rarely lasts. Testing error before a round of sights then adding or subtracting it is more practical.
Tom Sult, MD
Author: JUST BE WELL
justbewell.info
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