 |
| The three silver dots are lead weights. |
I was looking through some old photos and came across these images of a reproduction that I made for the
Matthew Legacy centre in Bonavista about 10 years ago. Its a
chip log, used to determine the speed of a sailing ship. The triangular board was tossed from the stern of the ship and dragged behind the vessel. As it dragged, the line would unspool from the reel. At certain intervals there was a knot of fabric tied to the log line. Each interval was marked with a different colour and texture of fabric so that the sailors could recognize them by both sight and feel. Using an hourglass as a timer they would count the number of knots unwound from the reel in a set amount of time. This is where the term "knot" came from to refer to the speed of a ship.
 |
| Oak, hemp line, assorted fabric knots, lead |
Photo Credits: Tim Rast
PDF
A course was set that ought get them there, while an estimate of the ship's speed was made at intervals, along with a note of the direction & force of the wind, & the difference between the ship's wake & its course, all to get an idea of where here, the ship, was, in relation to there, the home port & the destination. Once they had put out, the routine of navigation began: given a time of 30 seconds for the log being run out; after the first Knot was clear, marked by a red rag on the line, the length being divided into lots of 42' 3'', marked by knots in the line, the ship's distance travelled was reckoned. This was done hourly. Note was made of the wind, the course, & the ship's wake, or leeway. From this, & a knowledge of the sea current, its set & drift, an estimate of the ship's True Course was got [excerpt from Aftermath}
ReplyDeleteThe different-colored knots were on the sounding line, used for measuring depth: The knots on the logline were indistinguishable from each other, except for that first red-flagged one. As the chip was drawn back in, after the timer ran out, THEN the knots were counted, to determine the ship's speed. A 30-second glass required knots about 50' apart, not 42'.
ReplyDelete