The Beaufort Wind Force Scale In Britain and much of Europe, wind and vessel speeds are
described in knots. One knot equals a nautical mile covered in one hour, and is roughly equivalent to 1.15mph. Also used is the Beaufort Wind Force Scale. This was created in 1805 by Sir Francis Beaufort, a British naval officer and hydrographer, before instruments were available and has since been adapted for non-naval use. When accurate wind measuring instruments became available it was decided to retain the scale and this accounts for the idiosyncratic speeds, eg Force 5 is 17–21 knots, not 15–20 as one might expect. Under numbered headings representing wind force, this scale also provides the sea conditions typically associated with them, although these can be affected by the direction from which the wind is coming. The scale is reproduced on the opposite page.
Turtles in Our Wake_Book.indb 10
26/08/2011 15:38:15