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: Plastic sextants. was: GPS shortcomings.
    From: Frank Reed CT
    Date: 2005 Jun 11, 03:09 EDT

    George H you wrote:
    "Dave makes a fair point,  but as I see it, it would apply only to
    observations where a significant  fraction of the length of the sight-path
    to the horizon is over the land (or  sandy shore, or drying reefs,
    whatever). Otherwise, the surface temperature,  even in shallow water, would
    not differ all that much from the open sea,  except in some very-odd
    environments."
    
    There's more to it than that.  You can get more complicated layering of air
    layers with different temperatures  close to shore. Near Mystic, Connecticut in
    the spring and fall, it's not that  uncommon to see five or more arcminutes
    of anomalous dip, and this is for sights  taken on water (but within sight of
    land).
    
    -FER
    42.0N 87.7W, or 41.4N  72.1W.
    www.HistoricalAtlas.com/lunars
    
    
    

       
    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