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    Re: Joshua Slocum's navigational methods
    From: Frank Reed
    Date: 2005 Apr 16, 19:17 EDT
    Dan H, you wrote:
    "Since Slocum was an experienced see Captain of many years, and based on his
    writings. I would say he used Lunars more than once in his voyage."
    I think it's important to distinguish Slocum's circumnavigation from his earlier commercial voyages. The risk, whatever it may have been, was entirely his own when he was sailing around the world. He had no schedule to keep, no cargo to deliver, no crew to keep safe and secure...
    And you wrote:
    "He most likely use a book of trig tables at best for his calculations."
    That's what one would normally use for celestial navigation, lunars or otherwise, in that era. Or is that what you meant? Those trig tables would be found in any of the standard navigational manuals of the era. Perhaps he had Bowditch's "Practical Navigator" or more likely Norie's "Epitome of Navigation" (since it's established that he taught himself navigation originally --decades earlier-- from Norie).
    "It seems that how many times on a passage he would use lunars would depend on his confidence in his current Dead Reckoning position."
    Perhaps that's the point. Today we are taught that DR was a miserable burden for early navigators who were always hopelessly uncertain of their positions because DR was all they had. But the facts seem a little different. Navigators cherished their dead reckoning. It was the mark of a true mariner that he could sail an ocean by DR and scientific navigation "spoiled the fun", you might say. It reminds me of the status of standard celestial navigation today competing against GPS. The satellite systems spoil the fun, so some navigators enjoy testing themselves by doing pure celestial (+DR when the weather doesn't cooperate) to prove their mettle. The GPS is stowed away but available if confidence fails. Ironically, a 19th century navigator might have seen the finely honed and "scientific" methods of modern celestial navigation as something like a GPS today --much too easy and given a few days 'anyone can do it'.
    "He only mentions it once in the book"
    He also explicitly states in his book that he kept his longitude mostly by dead reckoning, which was why I originally asked if there was any other evidence on the matter. Nonetheless, some people who have read SAATW find all sorts of "clues" that they think point to extensive use of lunars. It looks like wishful thinking to me...
    And you wrote:
    "but at least once at mid passage and again sometime before making land seems prudent."
    Sounds about right for a prudent mariner with cargo or lives at risk. Then again, a prudent man would have gotten his chronometer repaired. Was Joshua Slocum a prudent man? Did he have anything to lose besides self-esteem? He was a man setting out to prove himself and make a little fame and money off it if possible. He succeeded more or less, but I wouldn't call him prudent. Do you remember reading in the book that he didn't know how to swim?
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