ground log

ground log

[′grau̇nd läg]
(navigation)
A device for determining the course and speed made good over the ground in shallow water, consisting of a lead or weight attached to a line and thrown overboard to the bottom; the course being made good is indicated by the direction the line tends, and the speed by the amount of line paid out in unit time.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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