Compass Work

true-virgins-make-dull-company

From Chart To Compass

For determining a compass heading to steer.

TRUE -E +W = Variation -E +W = MAGNETIC -E +W = Deviation -E +W = COMPASS

True Virgins Make Dull Company

  • TRUE heading
  • Variation - God made, the per chart difference in true vs magnetic north.
  • MAGNETIC heading
  • Deviation - Man-made, the error in the compass used to steer.
  • COMPASS heading
True To Compass Worksheet
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From Compass To Chart

For bearings, dead reckonings, and estimated positions.

COMPASS +E -W = Deviation +E -W = MAGNETIC +E -W = Variation +E -W = TRUE

Curry Dinners Make Violent Turds

  • COMPASS heading
  • Deviation - Man-made, the error in the compass used to steer.
  • MAGNETIC heading
  • Variation - God made, the per-chart difference in true vs magnetic north.
  • TRUE heading
Compass To True Worksheet

Bearing

  1. Take compass bearing
  2. Align the ruler with the measured bearing on the compass rose
  3. Walk rulers to bearing target
  4. Draw bearing line

Dead Reckoning

(dot with a half circle)

  1. Speed
  2. Time
  3. Heading

Estimated Position

(dot with a square, triangle for British)

  1. Speed
  2. Time
  3. Heading
  4. Leeway
  5. Tide

Reciprocal Bearings

If your compass bearing was the first number, then someone looking back at you would see their bearing as the second number. It is equally important to be able to quickly calculate the opposite bearing and NOT confuse the two.

010 and 190
020 and 200
030 and 210
040 and 220
050 and 230
060 and 240
070 and 250
080 and 260
090 and 270
100 and 280
110 and 290
120 and 300
130 and 310
140 and 320
150 and 330
160 and 340
170 and 350
180 and 360

"Move 2" Quick Reciprocal Finder

  1. Separate all bearings into three digits.
  2. The first digit in the bearing can not be less than zero or more than three.
  3. For bearings starting in 1 or 0, add a 2 to the first digit and then subtract a 2 from the second digit.
  4. For bearings starting in 2 or 3, subtract 2 from the first digit and add 2 to the second digit.

Example: Reciprocal of 090 is 270

  1. The first digit is 0 so we add 2 to the first digit. 0 + 2 = 2.
  2. Place the number "2" in the first digit spot to yield 290.
  3. For the second digit of 9, we subtract 2. 9 - 2 = 7.
  4. Place the number "7" in the second digit spot to yield 270.
  5. 270 is indeed the reciprocal of 090.
  6. Math check: 270 - 90 = 180

Example: Reciprocal of 237 is 057

  1. The first digit is 2 so we subtract 2 from the first digit. 2 - 2 = 0.
  2. Place the number "0" in the first digit spot to yield 037.
  3. For the second digit of 3, we add 2. 3 + 2 = 5.
  4. Place the number "5" in the second digit spot to yield 057.
  5. 057 is indeed the reciprocal of 237.
  6. Mach check: 237 - 057 = 180