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Subject: [Nml] Re: Chip log
From: Rick Emerson (rick@XXX.XXX)
Date: Sun Nov 15 1998 - 08:42:40 EST
Bob responded to a question I posed on the list about traverse boards
and whether anyone still uses one. The description of a chip log is a
pretty good one.
Rick
S/V One With The Wind, Baba 35
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[...]
From: bob-norris@XXX.XXX
To: rick@XXX.XXX
Cc: live-aboard@XXX.XXX
Subject: Re: Chip log
Date: Sat, 14 Nov 1998 21:02:23 -0500
Hi, Rick --
I think you asked about details on a chip log during the thread on
traverse boards. I lost your address, and was waiting for you to chime
in again. I remembered Baba 35.
Consulting my old Sea Scout manual, I find that it's a quadrant of wood,
weighted on the rounded side so it will float vertically, rounded side
down. A bridle, about 6' long in total, connects the lower corners, and
a tapered wooden plug is seized to the middle of it. The main length of
the log line is connected to a hole in the peak, and about 3' along it is
seized a wooden socket that fits the tapered plug. With the plug in the
socket, the chip sits upright, and when streamed stays virtually still in
the water as the ship moves on. When the timing is finished, a tug on
the log line pulls the plug out of the socket, the chip flips, going
nearly horizontal, and is easily retrieved.
Quoting: "The log line is small stuff, similar to the lead line, loosely
laid flexible untarred hemp being the best.
"(The line) is got on a stretch, wetted, and marked as follows: The log
line should be at least 150 fathoms long. Fifteen fathoms from the chip
is a piece of red bunting. This marks the end of the stray line, the
line allowed to run over while the chip gets settled comfortably in the
water.
"From this piece of bunting distances are marked off every 47' 3" by a
piece of fish line seized between the strands of the log line. Each
division from the red bunting is marked by knots in the fish line, one,
two, three, etc. [Ergo, "knots" -- Bob] These main divisions of the line
are each further subdivided into 5 equal parts by bits of white bunting,
indicating each 2/10 of a knot. Single tenths are arrived at by
estimation.
"The line, being marked, is wound on a large reel with handles.
"The other instrument, and a very important one, is the log glass, and
old-fashioned sand glass filled and regulated at the chronometer, to run
out in 28 seconds.
"Then we have the proportion...: Twenty-eight seconds is to one hour, as
47 feet, 3 inches is to one knot; or 6,080 feet (the sea mile, or length
of an average minute of arc on a meridian of the earth."
So: 28 sec. / 3600 sec. = 47.25 feet / 6080 feet = 1 knot (run out
when the log glass empties)
The more feet run out, the more knots and white buntings show up, and
obviously the faster you're going. When your helper calls "mark" as the
sand stops, grab the log line and count the knots and tenths. If the
plug hasn't pulled out yet, yank the line and reel it in.
Actually, get your apprentice to reel it in while you go put the peg in
the traverse board. Executive Privilege, you know, deserved by your
Superior Knowledge (which keeps you out of Situations that demand your
Superior Skill, etc.).
Hope this diverted your mind from contemplating the sorry state of the
world for a little bit :)
You might forward this to the Navigation list. I don't know the address.
BoB-)
S/V "High Hopes"
- -- "Gentlemen never sail to weather."
BoB-)
S/V "High Hopes"
[...]
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