|
|
|
|
|||||
|
||||||
Subject: [Nml] Traverse boards
From: Rick Emerson (rick@XXX.XXX)
Date: Fri Oct 30 1998 - 00:25:15 EST
While visiting the Dove in St. Mary's City, I wondered about the idea
of using a traverse board for taking quick notes for DR work. For
those who don't know what it is, there are two parts: a compass rose
and a rectangular array of holes. The rose is used to record heading
and the array records speed.
The speed section contains two sets of four rows of holes, like so:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o
Every half hour, at the turning of the 30 minute glass, a peg is put
in a hole to record the boat's speed. Each row represents one half
hour's reading of the log and each column is the boat's speed. The
total of eight rows makes up fours in a watch. Here's a filled out
board:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
o o * o o o o o o o o * o o o o
o o * o o o o o o o * o o o o o
o o o * o o o o o o * o o o o o
o o o * o o o o o o o o * o o o
At the start of the watch, the boat was doing 2 knots, speed increased
to 3 knots, fell back to 2 knots before hitting 4 knots at the end of
the watch.
The compass rose follows this concept albeit with a different layout.
Here the arrows of a 16 or 32 point compass are carved into the
board. On each arrow, a row of 8 holes is drilled in a line (forget a
drawing of that here!) so as to make 8 concentric rings of 16 or 32
holes each. To make a record of the boat's heading, the
whole board is turned so that the arrow for due north matches the
north arrow on the boat's compass and a peg is set into a hole on the
arrow closest to the boat's heading. For example, if the boat is
sailing due west, looking down on the compass, north is at the 3
o'clock position and the row of holes for west lies at 12 o'clock.
The first peg goes into the innermost hole, the second peg goes into
the next ring out from the center and so on. Even if the boat's
heading changes, each subsquent peg goes in the next ring out from the
last one.
At the end of the watch, there is a record of speed and heading
without having to write anything. The navigator then copies the
information onto paper and removes all pegs (the board I saw had the
pegs on a long string so they wouldn't get lost).
Anyway, comments on the idea of using something like this today?
Rick
S/V One With The Wind, Baba 35
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=
=-= TO UNSUBSCRIBE, send this message to majordomo@XXX.XXX: =-=
=-= unsubscribe navigation =-=
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=
|