Douglas Navigation protractor

360 marked in 1 intervals.

$7.95   ...item# 1852



5 inches square
Called "navigational" primarily because it goes continuously from 0 to 360 as a compass rose does. Use for plotting lines of position in celestial navigation or for general plotting and vector problems on plain paper that does not have a compass rose. In England and Australia it is more commonly called a Douglas Protractor, where they are popular for general plotting. (It is said to have originated in this form in 1914 by Captain H. P. Douglas, Superintendent of Charts in the Office of the Hydrographer in the Royal Navy.)

See Notes on plotting tools.

Note that this protractor is ideal for making a string plotter or "Sutherland Plotter," named after Chuck Sutherland, a kayaker who invented the concept. The protractor has a small hole in the center. Just run a light line (whipping twine or fishing line) through it, about 18 inches long, and tie a knot at both ends. Then you can use this to measure bearings and course lines from a chart. Very slick! Especially valuable for kayaks which have limited storage, but this arrangement is useful enough to be considered for all vessels. Chuck sells a model of this ready made for $5, but he uses a different style protractor (for more info: (215) 453-9084).

7/31/13 

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