1

The Magnetic Compass

!  Floating Pin !  Marine-

floating card !  Binnacle

Mounted !  Hand bearing

2

The Magnetic Compass !  Compass

card with points of the compass - used in the past

!  Today we usually use 360 degree compass

3

The Steering Compass

!  Binnacle or dash mounted

!  Bulkhead mounted

4

The Hand Bearing Compass !  Take bearings from

companionway (yacht) or wheelhouse

!  Use charted obvious targets

!  Good angle between bearings

!  Bearing on beam last

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5

The Electronic Compass !  Aslo called

fluxgate !  Main use: !  Hand bearing !  Autopilot

6

Compass Error - Variation

Caused by Earth’s magnetism

!  Varies from place to place

!  See compass rose on chart

!  Must be updated

7

Compass Error - Variation

8

Compass Error - Variation

9

Compass Error - Deviation !  Caused by

boat’s magnetism

!  Metallic objects !  Speakers !  Find difference

(from GPS) !  Make a

deviation card

10

Compass Error - Deviation

!  Boat’s magnetism

!  Metallic objects

!  Deviation card

11

Compass Correction

12

Compass Correction

Compass Cadburys Deviation Dairy

Magnetic Milk

Variation Very

True Tasty CADET When going from compass to true add east

E+ W-

090 C + 6 E 096 M - 8 W 088 T