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    Navigation Weekend: summary and thanks
    From: Frank Reed
    Date: 2008 Jun 19, 21:08 -0400

    This year's Navigation Weekend was a great success, and I would like to
    thank everyone who attended and everyone who gave a presentation. I'll say
    once again, thanks to Don Treworgy, director of the Seaport Planetarium, for
    his support for the Navigation Weekend. And also thanks to the Susan P.
    Howell Memorial Fund for providing some financial support for the events.
    At 10:30 in the morning on Friday, June 6, after unloading about a hundred
    pounds of Nautical Almanacs from my car (brought all the way from Chicago),
    I met with the early arrivals for the Navigation Weekend and gave them a
    brief tour of the grounds of Mystic Seaport in a light rain. This was a fine
    weekend to see the Mystic area despite the weather. Three square-rigged
    vessels and three fore-and-aft, schooner-rigged vessels filled the skyline
    with masts and spars. Not all of these are vessels in the museum's
    collection. The barkentine "Mystic" is the most impressive recent resident
    on the Mystic River estuary, and the schooner "Amistad," built by the
    shipwrights of Mystic Seaport for the film of the same name, had arrived for
    a little maintenance just a few days earlier.
    Our main activities officially got rolling with my little talk on the
    history of the modern Nautical Almanac and its fiftieth anniversary. It's
    amazing how little the modern Nautical Almanac has changed since 1958. I
    discussed how our modern almanac reulsted from the merger of the "American
    Nautical Almanac" and the British "Abridged Nautical Almanac" and also
    talked a little about the commercial almanacs which have had a significant
    impact on navigation in the past two centuries. For laughs, I "commissioned"
    a little birthday cake in the shape and gaudy colors of the US printing of
    the Nautical Almanac. Since Geoffrey Kolbe had travelled all the way from
    Scotland to join us, I awarded him the "Longitude Prize" which meant that he
    got to blow out the candle.
    The next event in the Navigation Weekend was a tour of the Collections
    Research Center at Mystic Seaport. This is what I call the "other museum."
    It is a large but inconspicuous building which houses the vast collection of
    manuscripts, objects, and small craft which are not on public display.
    Please note that Mystic Seaport charges for these tours. This cost was
    covered by the Howell Memorial Fund.
    At 3:15 on Friday, Geoffrey Kolbe delivered a fascinating presentation on
    his experiences with inland navigation and position finding. He described
    his adventures in the desert of western Egypt, keeping track of his position
    with dead reckoning as well as sextant sights with a bubble sextant. In
    addition, he related his experiences using theodolites to get position fixes
    and described some of the specialized instruments that have been developed
    for land-based position finding. A fascinating talk!
    The Navigation Weekend had two principal foci: navigation enthusiasts
    interested in the details and finer points of celestial navigation, mainly
    members of NavList, and educators who actively teach celestial navigation
    and see it as a foundation for teaching many other aspects of science. Carl
    Herzog's talk highlighted the suprisingly large number of sailing vessels
    engaged in sail training and educational programs at sea. Celestial
    navigation is actively taught and practiced on these vessels, though of
    course GPS is the real mode of navigation. Carl described the varying
    experiences that students have with celestial navigation, some get it right
    away (and not necessarily those with science experience), others never quite
    get it, but all come away with "aha" experiences about the motions of the
    Sun and stars that they will remember for a lifetime. Carl, by the way, has
    a foot in both camps. He used to post frequently in our online navigation
    discussions. These days he is mostly a NavList "lurker", but apparently
    that's because he's too busy doing celestial navigation instead of just
    talking about it...
    After Carl's talk at about 5pm, Ken Gebhart spoke to us about recent
    developments at Celestaire. He informed us that sales of sextants have been
    rising significantly in recent years. He sells about 1200 annually, both
    direct and to other retailers. Ken also filled us in on his experiences
    dealing with the folks in the UK who claim the copyright to the Nautical
    Almanac. The Nautical Almanac "office", of course, is now just two people,
    but they are under considerable pressure to make it pay by getting maximum
    royalties from the publishers of the Commercial Nautical Almanac (that's
    Celestaire essentially). After much discussion and debate in the past few
    years, Ken secured a deal which should keep the Commercial Nautical Almanac
    available at a reasonable price for years to come. Ken also showed off the
    newest sextant in the Astra line, complete with a very fine 7x monocular
    scope. I want one...
    The weather was still cool and dreary with low-hanging clouds so we did not
    have any opportunity to take sights on Friday evening. But those of us who
    gathered in Noank did get a look at Geoffrey Kolbe's beautifully restored
    Husun sextant c.1942. It looks like it came off the assembly line yesterday.
    He also built himself a 25x telescope for it to experiment with sextant
    sights requiring high accuracy, like lunars.
    Dinner on Friday was excellent: good food and good conversation. After
    dinner, I convinced a few folks to join me at John's in Mystic, a local pub.
    I spotted Amy Blumberg there and invited her over to chat with us by saying
    the magic phrase "could we talk to you about boats?" Amy is the owner and
    captain of the "Mystic," the largest sailing vessel built in the United
    States in sixty years. Great conversation.
    On Saturday morning, I talked about lunar distance observations and some of
    the aspects of clearing lunars, in particular the "fuss" in the 19th century
    over the "quadratic correction" in series methods. I also talked about some
    of the evidence in logbooks for the practice of lunar distance navigation
    and showed examples of the relative importance of some small sources of
    error in the clearing calculations.
    Next, Herbert Prinz talked about Lacaille's solar tables, showing very
    plainly how the tables were not dependent on modern models of planetary
    motion but in fact represented improvements derived from technology. The
    improved solar tables which were part of the revolution that led to
    longitude by lunar distances and eventually longitude by chronometers
    themselves depended critically on the development of astronomical clocks
    capable of accurately recording the intervals between transits of
    astronomical objects. Herbert's talk was packed with information, and I am
    only hitting the highlights here.
    We had scheduled time around noon on Saturday to take sights from a nearby
    location with a sea horizon, but the weather was somewhat oppressive and
    time was running short so we skipped that and settled for shooting a few
    lunars near the north end of Mystic Seaport. If you haven't been to
    Connecticut in the summer months, it may be hard to imagine how tropical the
    weather can become. It was hot, about 90 degrees F, and the humidity was
    high. The Moon was nearly lost in haze and high cirrus but after getting our
    bearings straight (I was turned about 20 degrees in azimuth from the correct
    directions as it turned out), we found it and managed to take some difficult
    lunar distance shots. NavList member Dave Walden had a chance to take his
    very first lunar. Geoffrey Kolbe shot a good series of lunars with his
    restored Husun and that 25x scope (I've misplaced these sights so please
    bear with me, Geoffrey... I'm sure they're not lost... I simply haven't
    finished unpacking). Vladimir Strelnitski, director of the famous Maria
    Mitchell Observatory on Nantucket, also had a chance to shoot some lunars.
    After shooting lunars and a brief lunch, we met in the Munson Room in the
    G.W.Blunt-White Building (formerly the library). Philip Sadler outlined the
    history of celestial navigation at Harvard University. It has been taught
    there in one shape or form since the late 17th century and continuously
    since 1896. The modern course is designed to teach very broad aspects of
    positional astronomy with celestial navigation as the practical foundation.
    Philip teaches this class with Eliza Garfield, who also attended. Eliza is
    presently captain of the Amistad and had just returned from a long sea
    voyage where students used celestial navigation extensively. Philip also
    played a short sample from a short documentary produced in 1987 called "A
    Private Universe" (see link on Resource page) which includes brief
    interviews with students at Harvard's commencement asking them to explain
    the seasons --and getting it quite wrong.
    Joel Silverberg, mathematics professor at Roger Williams University in Rhode
    Island, talked about the principles underlying Bowditch's method for
    determining latitude by double altitudes. This type of sight, which was
    extremely popular in navigation manuals in the late 18th and early 19th
    centuries allowed a navigator to deduce latitude by taking two sights of the
    same body separated by some interval of time. Joel is a skilled speaker, and
    he carefully stepped us through the procedure and the spherical trigonometry
    of Bowditch's otherwise cryptic method.
    Next up was a fascinating presentation by Mary Malloy and Steve Tarrant
    continuing Carl Herzog's discussion of the use of navigation by the Sea
    Education Association. As part of their program, students are given the task
    of charting a harbor, first with no tools, then with progressively more
    useful and technologically sophisticated tools. The emphasis is on letting
    the students discover the problems of mapping and re-inventing the
    solutions. In addition, Mary described how she has students study the modern
    North Atlantic pilot chart and use it to understand the early voyages of
    Columbus, who was tentatively discovering the most efficient way across an
    ocean whose currents and winds were, at that time, unknown. Mary and Steve
    also use early 18th century navigation manuals (e.g. Seller) to teach
    students the basic aspects of astronomy that are required for celestial
    Fascinating conversations in many topics continued over dinner at Jamms
    Restaurant in Mystic Saturday evening. There is nothing like talking with
    people in person to get you thinking about the future of navigation and
    navigation education. Highly recommended! During dessert, Don Treworgy, who
    has been working at the Seaport Planetarium since 1960, talked about the
    history of navigation at Mystic Seaport and also gave us a little background
    on Sue Howell's impressive contributions to navigation education and the
    tragic sinking of the Marques in 1984. Don also demonstrated his skill in
    the art of punnery and promised to get us all thinking about possibilities
    for activities in nautical astronomy for 2009 at Mystic Seaport.
    Sunday at noon, we got started with a presentation by Don Treworgy on the
    navigation of C.H. Townshend. As Don told us, Mystic Seaport has an
    extensive collection of Townshend's journals as well as his navigational
    instruments including a reflecting circle and one of his chronometers. Don
    noted that in one of his early logbooks Townshend wrote that ocean sailing
    was the 'life for me' but after a few decades at sea, Townshend was sick of
    it and wanted nothing more than to tend his oyster beds in New Haven harbor.
    Townshend was an experimental and enthusiastic navigator who took many
    exotic sights, seemingly for the fun of it. His logbook is also the only one
    I've seen from after 1850 with lunar observations. He has worked out one
    full lunar distance clearing calculation, in a tiny almost unreadable
    script, in a space that is smaller than 3 inches square! It's interesting to
    note that his reason in one case for taking a lunar was a hunt for a small
    mis-charted island in the Pacific. His chronometer was correct at that
    point, and he had sailed to the correct longitude but there was no island.
    So just to be sure he shot a lunar. Eventually it turned out that the
    "miserable island" was 25 miles away from the charted position. Townshend
    also notes in one of his journals that he "tried Sumner's method" for
    longitude and found it worked very well (note that this was thirty years
    after Sumner published and yet even this experienced and skilled navigator
    was only just getting around to trying it out).
    At 12:30 on Sunday, we jumped right into Herbert Prinz's talk on determining
    the Most Probable Position using a graphical approach. This is one of those
    topics where it helps to have a "captive audience". The conclusion is
    inescapable and unexpected. The algebraic proof is laborious, and, like most
    proofs, pretty dull. But if you don't see the proof you would probably never
    accept the conclusion. Really fascinating.
    And for the final scheduled talk, I chatted for a while about other methods
    of position finding that could be used at sea today especially to help
    elucidate the concepts of celestial navigation for those who teach it on the
    water. I started by talking about determining a position (using
    widely-available computer software) by observing artificial satellites. It
    was interesting to see how much discussion this generated. I suspect that
    this could be a very popular method of demonstrating the underlying ideas of
    celestial navigation. In addition, I talked about using lunar distances to
    generate lines of position and a position fix under modern circumstances
    where GMT is assumed known. Being able to animate the cones of position that
    underly this concept, I think, significantly helps explain what's going on.
    I also presented a "complete error budget" for this method: $14.95 (that's a
    little inside joke).
    Since we dropped the originally scheduled time to explore the exhibits of
    Mystic Seaport, there was time for one additional presentation. Some of our
    guests had to depart to make flights or drive home, but about half of us
    stayed to hear Stan Klein discuss the development of his navigation
    software. It's an interesting product used to teach Power Squadron
    navigation classes. He described how he faced some resistance in the early
    days from people involved in celestial instruction in the Power Squadron who
    were concerned that students might use such software to "cheat" on their
    exercises. Stan also filled us in on some of the fascinating recent history
    of other software developers who have worked on similar navigation tools.
    All in all, an interesting story and a nice way to close out the events of
    the Navigation Weekend.
    Six of us decided to have an early lunch after the end of the conference,
    and Herbert Prinz reminded me that we had a standing invitation for a tour
    of the barkentine "Mystic". We walked the half-mile from Mystic Seaport to
    the drawbridge while Geoffrey Kolbe informed us that the Sahara Desert was
    not as uncomfortable as Mystic's tropical weather --and he wasn't kidding,
    it was hotter on Sunday than Saturday and still stifling humid. After
    spending a few minutes in the marine goods store on the block which actually
    had two sextants on sale (!), a Simex in good condition as well as a Davis
    plastic sextant, we talked our way into getting a tour from the crew working
    aboard the "Mystic" (Amy wasn't there, but one of the young women aboard
    remembered us as "the navigators from the other night"). It's an impressive
    vessel, designed for passenger-carrying cruisess and excursion sailing. We
    all took a good look at the navigator's station --no sextant there...
    Over our late lunch, in a nice restaurant with a terrific view, we watched
    the clouds roll in from the west as that tropical Connecticut air boiled up
    into impressive thunderstorms. Gusty winds whipped up the surface of the
    Mystic River, the steamboat Sabino, evening cruise cut short, had to race
    back to the Seaport. And the rain came pouring down. Why did it rain? Why
    naturally, because we navigators, prepared for any eventuality, had left our
    cars behind and walked to lunch and none of us had brought umbrellas. :-)
    But the showers soon ended, and it all worked out in the end.
    The 2008 Navigation Weekend was a great success, and I only wish that more
    of you could have attended. For those of you did attend, I sincerely enjoyed
    meeting and talking with all of you.
    Navigation List archive: www.fer3.com/arc
    To post, email NavList@fer3.com
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