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Boxing the compass

 
Sci-Tech Dictionary: boxing the compass
(′bäks·iŋ thə ′käm·pəs)

(navigation) In nautical practice, calling out in sequence the names of the points (and sometimes the half and quarter points) indicated by the compass of a maneuvering vessel.


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Wikipedia: Boxing the compass
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A 16-point compass rose
A 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 course or azimuth) in a general or colloquial fashion, without having to resort to computing or recalling degrees.

The set of 32 named points can be further divided into a set of 128 named directions using quarter-points,[1] although for communicating heading these fractional points have been superseded by degrees measured clockwise from North.

Contents

Compass points

A simple algorithm can be used to convert a heading to an approximate compass point:

  1. Divide the heading in degrees by 11.25 (360/32) to get to the case of 32 named points.
  2. Add 1.5 to center the named points in their respective sectors on the circle, since north is 1 in the table instead of 0. If the result is 33 or more, subtract 32 to keep within the 32-point set.
  3. Now look up the integer part of the result in the table below.

For example:

A heading of 75°, divided by 11.25 gives 6.67, added to 1.5 gives 8.17, truncated to give 8. 8 in the table below corresponds to east by north.

# Compass point Abbr. Traditional wind point Heading Heading Range
1 North N Tramontana 0.00° 0.00 -     5.62°
2 North by east NbE 11.25° 5.63 -   16.87°
3 North-northeast NNE 22.50° 16.88 -   28.12°
4 Northeast by north NEbN 33.75° 28.13 -   39.37°
5 Northeast NE Greco or Bora 45.00° 39.38 -   50.62°
6 Northeast by east NEbE 56.25° 50.63 -   61.87°
7 East-northeast ENE 67.50° 61.88 -   73.12°
8 East by north EbN 78.75° 73.13 -   84.37°
9 East E Levante 90.00° 84.38 -   95.62°
10 East by south EbS 101.25° 95.63 - 106.87°
11 East-southeast ESE 112.50° 106.88 - 118.12°
12 Southeast by east SEbE 123.75° 118.13 - 129.37°
13 Southeast SE Sirocco 135.00° 129.38 - 140.62°
14 Southeast by south SEbS 146.25° 140.63 - 151.87°
15 South-southeast SSE 157.50° 151.88 - 163.12°
16 South by east SbE 168.75° 163.13 - 174.37°
17 South S Ostro 180.00° 174.38 - 185.62°
18 South by west SbW 191.25° 185.63 - 196.87°
19 South-southwest SSW 202.50° 196.88 - 208.12°
20 Southwest by south SWbS 213.75° 208.13 - 219.37°
21 Southwest SW Libeccio 225.00° 219.38 - 230.62°
22 Southwest by west SWbW 236.25° 230.63 - 241.87°
23 West-southwest WSW 247.50° 241.88 - 253.12°
24 West by south WbS 258.75° 253.13 - 264.37°
25 West W Poniente or Zephyrus 270.00° 264.38 - 275.62°
26 West by north WbN 281.25° 275.63 - 286.87°
27 West-northwest WNW 292.50° 286.88 - 298.12°
28 Northwest by west NWbW 303.75° 298.13 - 309.37°
29 Northwest NW Mistral 315.00° 309.38 - 320.62°
30 Northwest by north NWbN 326.25° 320.63 - 331.87°
31 North-northwest NNW 337.50° 331.88 - 343.12°
32 North by west NbW 348.75° 343.13 - 354.37°
1 North N Tramontana 360.00° 354.38 - 360.00°

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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Sci-Tech Dictionary. McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved.  Read more
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