Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
    Re: Temperature effect on sextants
    From: Greg Rudzinski
    Date: 2017 Aug 6, 14:28 -0700

    Mark,

    Better to do this experiment with the same sextant.  First put in the fridge without scope. Right after it is removed from fridge measure index error with scope attached (condensation on mirrors may delay observations).  Let sit in Sun without scope attached ( direct Sun on scope lens for long periods is bad for the lens coatings. A hole might get burned into something also.). Repeat index error measurement with scope attached to compare. There shouldn't be much difference on metal sextants. Plastic sextants (especially black sextants) will show differences in minutes of arc. Best to keep all sextants out of direct sunlight.

    I noticed just now testing a plastic Davis MK 15 that the largest observed change occured in side error (at least 4'). Index error changed in both directions 2'  depending on what side was exposed to the Sun. Don't expect to come up with some way to compensate for this expansion and contraction effect. I advise removing sextant from box ten minutes or so before checking index error / observations. Always shade from direct sunlight when not making observations.

    Greg Rudzinski

    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
    Email:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site