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    Re: A One-Hour Presentation on Celestial Navigation
    From: Bob Goethe
    Date: 2016 Mar 18, 12:41 -0700

    >>You mentioned that 'One person asked about Slocum's $5 clock, so I touched on the idea of the lunar.'  OK. I'll bite. What did you say on this? How did you connect a lunar with Slocum's little clock? I would say that there's no connection, but there's a lot of confusion on this topic.<<

    I said that while, in principle, John Harrison had solved the problem of finding longitute, in practice a lot of people continued sailing without chronometers (because of their expense) for a long time, and navigated via latitude-sailing.  My understanding is that James Cook sailed to Tahiti using K1, the first copy of H4...and that the value of that chronometer exceeded the value of the rest of his ship.

    I said that Slocum's $5 clock was not much good for anything, navigationally, and that Slocum did a lunar - measuring the distance between the edge of the moon and a star - to work backwards to derive the time.  But he talked about his long struggle with tables, and as nearly as I could tell he only did a lunar this once.  He travelled across the Pacific by positioning himself on the right latitude and then staying there until he got to where he wanted to go.  His reference to the $5 clock was, I think, mostly there for humorous effect.

    I went on to say that while all naval ships certainly had chronometers in the early 20th century, as well as almost all merchant ships, recreational sailors waited until Seiko introduced the quartz watch to REALLY be able to afford economical celestial navigation.  This means that the golden age of celestial for small boat sailors lasted only from 1969 to sometime between 1992 and 2002, when GPS receivers became easily affordable:  a golden age that lasted no more than 30 years or so.

    Of course, until fiberglass sailboats began to be constructed after WW2, there were very few shoestring-budget sailors.  Prior to WW2, a lot of the "recreational sailors" were pretty wealthy...so they probably did have chronometers.  But I elected to practice a bit of simplification in my talk, and focused on the kinds of men in the audience before me...none of whom would be numbered among the Rockefellers or Vanderbilts.


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