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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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