NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Traverse boards
From: Rick Emerson
Date: 1998 Oct 29, 10:25 PM
From: Rick Emerson
Date: 1998 Oct 29, 10:25 PM
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@roninhouse.com: =-= =-= navigation =-= =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=