Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: Are higher altitude sights inherently less accurate?
    From: John Karl
    Date: 2012 May 2, 19:23 -0700

    For once I disagree with Geoffrey. He says, "The error how vertical your sextant is becomes rapidly more important [at higher altitudes]. And in consequence, errors in high altitude sights will increase."

    The opposite is true. The error with sextant "tilt" is max at 45d altitude and decreases to zero at 90d altitude, for any given tilt angle, as the attached table shows.

    It is true that it's uncomfortable, even weird, swinging around in azimuth as you rock the sextant looking for vertical. Here's were the traditional half-silvered horizon mirror can help. Just keep the vertical division of the mirror perpendicular to the horizon (as you pivot around awkwardly on one foot) and your altitude error should be within reason, just as the attached table shows.

    Happy highs (altitudes),

    JK
    ----------------------------------------------------------------
    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com
    ----------------------------------------------------------------

    File:

      
       
    Reply
    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