Boxing the compass


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A 16-point compass rose
A hypothetical 32-point compass rose
A historical compass card

Boxing the compass is the action of naming all thirty-two principal points of the compass in clockwise order. Such names, formed by the initials of the cardinal directions and their intermediate ordinal directions, are accepted internationally, even though they have their origin in the English language, and are very handy to refer to a heading (or a course) in a general or colloquial fashion, without having to resort to computing or recalling angle numbers. Despite the name of the 1959 Alfred Hitchcock movie, North by Northwest, there is no such direction. However, old-timers allow three letter directions to have a 'by' inserted between the first and second letter.[citation needed] Hence, NNW becomes North by Northwest, per Hitchcock's title.

The set of 32 named points can be further extended to a set of 128 named points using fractions [1], although these fractional points are nearly unheard of.

A simple algorithm can be used to convert a heading to an approximate cardinal direction:

  1. Divide the heading in degrees by 360 to get the fraction around the circle.
  2. Multiply the result by 32, in the case of 32 named points.
  3. Add 0.5 to center the named points in their respective sectors on the circle.
  4. Since the 32-point set is used, look up the integer part of the result in the table below after adding 1, since north corresponds to 1 in the table below instead of 0.

For example:

A heading of 75°, divided by 360 gives 0.208, multiplied by 32 gives 6.66, added to 0.5 gives 7.16, truncated to 7, added to 1 to give 8. 8 in the table below corresponds to east by north.

Contents

Compass points

# Compass point Abbr. Traditional wind point True heading
1 North N Tramontana 0.00° or 360.00°
2 North by east NbE 11.25°
3 North-northeast NNE 22.50°
4 Northeast by north NEbN 33.75°
5 Northeast NE Greco or Bora 45.00°
6 Northeast by east NEbE 56.25°
7 East-northeast ENE 67.50°
8 East by north EbN 78.75°
9 East E Levante 90.00°
10 East by south EbS 101.25°
11 East-southeast ESE 112.50°
12 Southeast by east SEbE 123.75°
13 Southeast SE Sirocco 135.00°
14 Southeast by south SEbS 146.25°
15 South-southeast SSE 157.50°
16 South by east SbE 168.75°
17 South S Ostro 180.00°
18 South by west SbW 191.25°
19 South-southwest SSW 202.50°
20 Southwest by south SWbS 213.75°
21 Southwest SW Libeccio 225.00°
22 Southwest by west SWbW 236.25°
23 West-southwest WSW 247.50°
24 West by south WbS 258.75°
25 West W Poniente or Zephyrus 270.00°
26 West by north WbN 281.25°
27 West-northwest WNW 292.50°
28 Northwest by west NWbW 303.75°
29 Northwest NW Mistral 315.00°
30 Northwest by north NWbN 326.25°
31 North-northwest NNW 337.50°
32 North by west NbW 348.75°

See also

References

  1. ^ Great War Primary Documents Archive, "Boxing the Compass" Accessed November 12, 2008

External links

  • Wind Rose – discusses the origins of the names for compass directions.
  • Compass Rose - Actual Compass Roses for the Home.






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