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    Re: Traverse board and the log.
    From: tony
    Date: 2005 Dec 2, 18:43 +0000

    About eight times, I believe, and certainly after any major change of
    course.
    
    on 2/12/05 11:39 am, George Huxtable at george@HUXTABLE.U-NET.COM wrote:
    
    > Any ideas about this question?
    >
    > In the days of streaming the log, how many times, in a watch of four hours,
    > would it normally be streamed? Details follow.
    >
    > ===============================
    >
    > Thanks to all the Nav-l members who have provided such helpful responses to
    > my request for a drawing of a traverse-board, both on-list and off it.
    >
    > Renee Mattie has helpfully written-
    >
    >> There is a very clear jpg of a line drawing of a traverse board at
    >> http://www.rootsweb.com/~mosmd/travbrd.htm
    >> As this is an educational website, the author may be willing to allow you
    >> to
    >> reuse it in your publication, and even to make modifications.
    >>
    >> It would be easy to remove the text at the top and/or to add column
    >> headings
    >> for the knot-log pegs at the bottom.
    >> Presumably, the column headings should be I through XI and 1/4, 1/2, 3/4
    >> as
    >> shown in the photo at http://www.californian.org/ebay/htm/traverse.htm
    >> (Or left blank as in
    >> http://www.maritime-museum.aland.fi/current/g/pinkom_l.jpg )
    >>
    >>
    >> It wouldn't even be all that difficult, using available drawings and
    >> photos
    >> as a reference, to draw one from scratch.
    >
    > =========================
    >
    >
    > Renee, and others, have pointed to the useful and interesting website of
    > Duane A Cline, at-
    > http://www.rootsweb.com/~mosmd/travbrd.htm
    >
    > You can go to that site to see his drawing, and his text. The text is also
    > copied below.
    >
    > ==========================(quote from Cline)
    > ==========================
    >
    > Navigation: The Traverse Board
    > The Traverse Board was used as a memory aid by navigators as early as the
    > seventeenth century, and would certainly have been used by the officers and
    > crew on the Mayflower. With this simple device they were able to record how
    > far and in what direction they had traveled during each four-hour watch.
    >
    > It consisted of a simple wooden board, equipped with pegs which were
    > inserted into a series of holes.
    >
    > The upper portion of the board was marked out in the thirty-two points of
    > the compass. Notice there are a series of 8 holes radiating out from the
    > center to each of the thirty-two points of the compass on the outer circle.
    > A set of eight pegs is attached to the center of this circle.
    >
    >
    >
    >
    > USING THE TRAVERSE BOARD
    >
    >
    >
    >
    > At the end of each half-hour of the watch, the officer on duty would take a
    > peg and stick it into the hole in the compass bearing on which the ship had
    > run during the half-hour just completed.
    >
    > The first half-hour of the watch was represented by the first circle of
    > holes nearest the center of the compass, and so on. At the end of the
    > four-hour watch all of the pegs would have been used, with the last peg
    > inserted in the outermost circle of holes.
    >
    > To record the speed at which the ship had been traveling, the rows of holes
    > at the bottom of the board were used. At the center of this row of holes was
    > another set of eight pegs on strings. The holes to the left side of the
    > center were used for the first two hours of the watch, while those on the
    > right side were used for the last two hours.
    >
    > At the end of the first half-hour of the watch, the officer in charge would
    > insert a peg at the hole which represented the knots-per-hour at which the
    > ship had been traveling. [Remember that this was determined by using the
    > log-line.] If the ship had been traveling at four knots-per-hour, the
    > officer would count over from left to right on the first row of holes and
    > place the first peg in the fourth hole.
    >
    > At the end of the four-hour watch, the officer in charge would transfer this
    > information from the traverse board onto a slate -- or perhaps a piece of
    > paper. At the end of the day the master or captain of the ship would use
    > this information to write up his log, which was a detailed record of the
    > voyage. The navigator would use the same information to chart the progress
    > of the voyage on his maps.
    >
    > Traverse Boards provided a simple and relatively foolproof method of
    > recording information which could be used even the foulest weather.
    >
    > It is interesting to note that the use of the traverse board was adopted by
    > the navigators from northern Europe and England and was used as late as the
    > beginning of the twentieth century. No examples of traverse boards from the
    > Mediterranean navigators has ever been found.
    >
    > ========================== (end of quote from Cline)
    > ==========================
    >
    > There's no problem, to my mind, in the upper, dartboard-like, part of the
    > picture, of 32 "spokes", each containing 8 holes. Clearly, that refers to 8
    > successive observations of vessel's course, at half-hour intervals, to the
    > nearest compass-point. They could be entered in an order, inner-to-outer, as
    > Cline suggests, or the opposite. It wouldn't matter, as long as it was
    > agreed.
    >
    > But the difficulty that worries me arises with the 4 rows of "speed" holes,
    > below the dartboard, where Cline suggests -
    > "To record the speed at which the ship had been traveling, the rows of holes
    > at the bottom of the board were used. At the center of this row of holes was
    > another set of eight pegs on strings. The holes to the left side of the
    > center were used for the first two hours of the watch, while those on the
    > right side were used for the last two hours."
    >
    > That would indeed allow for 8 speeds to be recorded during the 4-hour watch,
    > at half-hour intervals, one speed for each pegged course. However, I suggest
    > that the evidence of preserved traverse boards shows that many (perhaps all)
    > were not intended to be used in that way, but instead for four speeds to be
    > measured over the watch, one for each row of pegs at intervals of an hour.
    > And not in two separate blocks of four, to the left and to the right, as
    > Cline has suggested..
    >
    > That question may be have been somewhat confused by overpainting and
    > redecorating of the boards over the years, as a result of on-board
    > weathering from the harsh environment, or from the well-meaning attentions
    > of collectors or museum curators.
    >
    > Cline's model for his drawing may be, at a guess, the board illustrated in
    > "The Haven-seeking Art", by E G R Taylor, (my ed. is 1971) plate X11 ("found
    > in the Isle of Barra, 1844"). At least, the decorative key-shape at the top
    > corresponds closely to his. The bundle of 8 strings emerges from between two
    > columns, To its left, there are 10 columns, which have been marked 1 to 10.
    > To its right, the columns have been marked, starting again at 1. But there
    > are only 9 columns to the right, so they are marked 1 to 9. It makes little
    > sense, to me, for the board to be designed to mark speeds to 10 knots over
    > the first half of the watch, then speeds up to 9 knots over the second half.
    > And that's one difficulty; how do you split a speed block into two equal
    > parts, when it comprises an odd number of columns, as is commonly the case?
    >
    > So I doubt whether that example was intended to record 8 speeds in two
    > blocks, but suggest instead 4 speeds, each given a single row, right across
    > the board.
    >
    > But if the speed-block had been designed to record only 4 speeds, why did it
    > need a bundle of 8 pegs? Well, that's made clear in certain traverse boards,
    > which show, at the right, either a single column marked 1/2, or a set of 3
    > columns marked 1/4, 1/2, 3/4. By pushing one peg into a whole-knots hole,
    > and another into a fractional-knots hole, the precise speed can be noted.
    >
    > So the illustration in the Taylor book could well have been intended to
    > record 4 speeds in a watch, using its 19 pegs to show a maximum of 16 3/4
    > knots, to the nearest quarter-knot, using if necessary 2 pegs for each row.
    >
    > That may seem an unreasonably high speed to allow for. For a steamer, that
    > might be the case, but the American clipper ships were claiming ultimate
    > speeds of around 20 knots (see David MacGregor, "Fast Sailing Ships", 1973,
    > page 190). With a good wind from the right direction, they were the fastest
    > things afloat, by a long way.
    >
    > The scale on the speedometer of my car reads to 140 miles per hour, though I
    > couldn't (illegally) get the thing above 100, downhill and downwind, try as
    > I might. In a similar way, a mariner wouldn't wish to be limited by the
    > speed-range of his traverse board!
    >
    > How often, then, would a sailing vessel stream the log? Lecky, in
    > "Wrinkles", in the late 1900s, dealing with steamship matters to a great
    > extent, only expected the log to be streamed at 2-hour intervals. But steam
    > vessels were not so subject to the caprice of the wind, and log readings
    > might have been required more often, for sailing vessels. Perhaps every
    > hour, but 8 times in a watch (every half-hour) seems to be overdoing it
    > somewhat. It seems to me likely, to fit in with evidence from traverse
    > boards, that an hourly log reading would be noted on the board, in
    > association with a pair of courses.
    >
    > Does anyone have views, or even better, evidence, as to how often the log
    > would be streamed, and exactly how it would be pegged-up on the board?
    >
    > I now have an email address for Duane Cline, so I will send him a copy of
    > this mailing.
    >
    >
    >
    > George
    >
    > ===============
    >
    > contact George Huxtable at george@huxtable.u-net.com
    > or at +44 1865 820222 (from UK, 01865 820222)
    > or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
    
    

       
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