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: What's "under the hood" of the Raft Book?
    From: Greg Rudzinski
    Date: 2017 Oct 21, 10:47 -0700

    Tony,

    -16' is just the semi diameter of the Sun to be applied to the 0° Sun upper limb Hs value.  Inside front cover of the Nautical Almanac has 0° refraction  -33.8'. Now also subtract dip for someone sitting in a raft -2.0' then -16.0' semi diameter of Sun for a grand total -51.8'.  This is a negative Ho altitude which may cause sight reduction trouble for some. A work around is to hand make a kamal  from 1° to 4° so that a positive Ho can also be observed and eliminate all the negatives.  I like using 1 cm per 1° scale held at 22 inches from eye. Attached shows a variation of this concept using a standard index card with scale to 9° using a quarter inch hole filtered with solar film.

    Greg Rudzinski



    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