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    Re: 3-Star Fix - "Canned Survival Problem"
    From: Jeremy C
    Date: 2008 Jun 13, 23:14 EDT
    I wrote:
    > Since I was bereft of electronic gadgets, I did this with a plotting
    > sheet, 2 triangles, a pair of dividers, 2 books, a pencil, and small
    > piece of scratch paper (wouldn't have reams of paper in the
    Lifeboat).

    Greg replied:
    Glad *somebody* actually noticed that part of the exercise (though I
    did say the navigator managed to grab all of the navigation tools
    before abandoning ship, but your method is also valid).
     
    I'm not quite sure what you're getting at here.  About the only thing I really
    missed was my regular pocket calculator when doing this.  The computer
    is nice and fast, but not really necessary.  I am so used to doing these sights
    with just books and plotting tools, I never learned to miss any electronic
    gadget except a calculator to make the arithmetic a bit quicker and do
    the interpolations.  Now if you asked me to do sailings using trig tables,
    that would be a different story. 
    I wrote:
    > I used an assumed position method and HO 229
    Greg replied
    I used 34° N and longitudes based on getting whole numbers for the
    LHAs.
     
    When I say "assumed position method" that is exactly what I mean; whole
    latitudes and assumed longitudes to get whole numbers of LHA.

    Greg wrote:
    How about across a parking lot?...  ;-)
    Wonder if a dip short correction would have made that "artificial
    sight" more accurate?...  ;-)
     
    Well the table in Bowditch for dip short of the horizon has a minimum distance of about 0.2 nm, although you can probably use the formula to get shorter distances, but I am not sure of the accuracy..  In any case, at 20 ft above sea level, your dip at 0.2nm is 56.7 minutes.  I'm not sure how that compares with your observed Hs and the Hs you got after the numbers were massaged a bit.  This whole idea might inspire me to shoot and then post an exercise.  Since the island is to our East, I should be able to shoot some sunlines based on the shoreline.  Radar will give me the range so we should be fairly accurate.
     
    Jeremy





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