A KNOTTED LINE TO
DETERMINE SPEED
A knotted line has a series
of evenly spaced knots tied along its length and was attached to a
triangular block of wood.
The calculate a ships speed
a sailor using a hourglass as the timer, tossed the end of the line
with the wood block overboard. As the line played out into the sea,
the sailor counted the number of knots that passed through his hands
before the sand in the hourglass timer ran out.
He could than estimate the
number of “knots” that his ship was traveling through the waters
of the sea. The tides and currents also had to be factored into the
calculations which at that time more of an art than a science.
Source: Ben Franklin Voyage
London to Philadelphia (1905 Albert Henry Smyth) / Michael Morgan's
Delaware Diary, Delaware
Coast Press, June 21, 2017. Abstract by Harrison.
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