I’ve been reading the story of Captain James Cook’s life and have found a treasure trove of nautical terminology. I began to wonder how the words came about, and will be treating you to some information from a wonderful reference site (listed below).
“An early form of measuring a ship’s progress was by casting overboard a wooden board (the log) with a string attached. The rate at which the string was payed out as the ship moved away from the stationary log was measured by counting how long it took between knots in the string. These measurements were later transcribed into a book. Hence we get the term ‘log-book’ and also the name ‘knot’ as the unit of speed at sea.”