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    Re: Impressed with the Raft Book
    From: Christian Scheele
    Date: 2010 Jan 28, 11:52 +0200

    Mr Boersma,
    I am getting an experiment of my own under way. I myself don't sail but live a 
    few minutes away from a sea-level view of sunset, not sunrise, but that I 
    have all year round. I could drive out to Cape Aghulas, about 200 miles away, 
    then wait for "perfect" or excellent conditions. From there I have a view of 
    both sunrise and sunset more or less at any time of the year between August 
    and May. I am making rough estimates of the sun's declinations. Weather 
    conditions are another matter, but clear skies are "common". I don't know 
    what the coast line is like there, whether I would be making my observations 
    from a beach or from the top of a cliff. If not at sea-level, I could use two 
    level, vertical boards and an improvised right angle to find observed 
    altitude zero which needs to be further adjusted for refraction. Of course, I 
    could stay right here where I lack a view of sunrise and use a shadow stick 
    (a trusty kebab skewer) and the equation of time to get noon (using knowledge 
    of my longitude would be cheating) and then multiply the time from noon to 
    sunset by two to get the length of day. W
    Christian Scheele
    Cape Town
    ----- Original Message -----
    From: "mike boersma" 
    To: NavList@fer3.com
    Sent: Thursday, January 28, 2010 1:30:46 AM GMT +02:00 Harare / Pretoria
    Subject: [NavList] Re: Impressed with the Raft Book
    Mr. Scheele 
    As cloudy and cold as it has been here in Western Michigan, I instead used 
    data from the US Naval Observatory for my local area as the time for the 
    sunrise, sunset, and length of day. 
    I compared this data to the data in Gatty's charts. 
    I will repeat the experiment again when it is warmer without using the USNO 
    data to see how things work in real life. 
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