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    Lunar mechanics and Double Alts.
    From: Doug Royer
    Date: 2003 Apr 28, 18:25 -0700

    Thank you everyone who responded offlist to my STCW inquirey.It amazes me
    how much it costs to maintain or upgrade a lisence or mmd these days.
    Mr. Kenchington,your explaination in 7 paragraphs about slip, revs. and the
    exam question was better than I could do in all my letters.Thank you.
    To answer the offlist questions about the 3x and 6x optics on the Tamaya.I
    didn't write the magnifacation wrong.I ordered the sextant in 1989 and
    bought the Tamaya,new without the 4x and 7x, in Owase,Japan in 1990.It is an
    MS-733 series.I bought the 3x and 6x sights made for the Tamaya from
    Takahashi.The 6x has a fine crosshair in the optics that is a helpfull
    feature.There are things one can buy in Japan for other Japanese products
    not offered outside the country.I was advised not to buy magnifacation over
    6x.I spent a little more cash but got what I wanted.
    Mr. Huxtable and Mr. Pearson,thank you for the time and effort you put forth
    in both writeing pts. 1-4a and creating the websight.My compliments.Don't
    get your hopes up about me being the 1st to attempt a Lunar at sea on a
    transit.I plan to go to sea only enough to satisfy the minimun time needed
    to keep the lisence current. I am definitely going to study the proceedure
    closely over the next week.After advice on and offlist,I ordered a copy of
    Mr. Stark's book.
    04-26 turned out to be the perfect day to attemp this.Atmosphere was crystal
    clear and between 50*F at the start and 68*F at the close with not a cloud
    all day.Started out useing the 6x and just kept it on.I only used 2 shots
    and times for each distance measured because I didn't know if I was going to
    be proficiant enough for more in the time frame I had to work with.1st round
    of sights at 0458zt.Moon's disk-Mars combination.0504zt Moon's upper
    horn-Enif.0548zt Moon-Venus.0610zt Moon's lower horn-Fomalhaut.Could barely
    see Fomal. at this time but compleated it.0703 and 0849zt Moon-Sun.A word
    about the Tamaya.Checking the error in all the proscribed ways that machine
    just doesn't need any adjustment.Error has been < 0.2' off arc for so long
    in many temp. variants sometimes I think it's broke.It isn't.
    I spent the rest of the day and evening doing Double Altitudes because I
    haven't much experiance doing them.I used Mr. Huxtable's suggestion to use
    molassas(I had to use dark Karo syrup as I couldn't find real molassas),and
    it worked great.Good image reflections even on Sirius at twilight and it has
    good surface tension.The averaged altitudes were all < 0.1' of the Ho
    calculated by the software I use.I used a Casio quartz digital watch set to
    GMT by radio signal and a Hamilton stop-watch to time each shot.Do you guys
    use this method or another?
    What number of sights do you guys use to average the each distance?A good
    many people responded that they calculate the alt. of each body.Is this or
    actually takeing the Double Alts.the preferred way?If one doesn't really
    know precisely where one is wouldn't measureing the alts. give you a better
    end result of the Lunar than calculateing the alts.?Is calculateing the
    alts. a step saver or am I just not seeing something? I need guidance on
    this matter.From reading the stories about the L + C exp.,they measured the
    alts. instead of calculateing them.Does calculateing the alts. give you a
    better time factor to work with?

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