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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
navigation.

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.


 -FER


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