1. Corrected by slewing the Spheres
Coefficient ‘E’
It is the mathematical representation of deviations on Cardinal Headings.
Caused by induction of Horizontal Symmetrical Soft Iron about a 45 degree line relative to the ships head.
Corrected by slewing the Spheres

2. Heeling Error
Poles beneath the compass position

3. Coefficient ‘J’
It is the mathematical representation of deviations heeled 1degree to port and 1 to starboard

13. 1st cause- FORCE R VERTICAL COMPONENTSHIPS PERMENANT FIELD
WHETHER HEELED TO PORT OR STBD
BLUE UP - HIGH SIDED H.E,RED UP LOW SIDE HE

14. 2nd cause k ROD EFFECT
INDUCED VERTICAL SOFT-IRON ABOVE OR BELOW COMPASS
WHETHER HEELED TO PORT OR STBD
BLUEUP - HIGH SIDED H.E. RED POLE UP- LOW SIDE HE

15. INDUCED HORIZONTAL SOFT-IRON
3rd cause E ROD EFFECT
INDUCED HORIZONTAL SOFT-IRON
NORTHERN HEMISPHERE
HIGH SIDED H.E.

16. 3rd cause INDUCED HORIZONTAL SOFT-IRON DUE TO Z
COMPENSATION WITH SOFT-IRON SPHERES

17. TERMINATING BELOW COMPASS
4th cause g ROD EFFECT
INDUCED F&A SOFT-IRON
TERMINATING BELOW COMPASS N
INDUCTION BY H FIELD OF ERATH MAGNETISM

18. TERMINATING BELOW COMPASS
4th cause
INDUCED F&A SOFT-IRON
TERMINATING BELOW COMPASS
HEADING NORTH
NORTHERN HEMISPHERE
LOW SIDED H.E.

19. TERMINATING MATERIAL BELOW COMPASS
HEADING EAST/WEST
ERROR = NIL
TERMINATING MATERIAL BELOW COMPASS

20. 5TH CAUSE OF HEELING ERROR DUE TO C ROD
INDUCED MAGNETISM IN VERTICAL SOFT IRON FORD AND ABAFT INDUCED BY H

21. Heeling Error
Correction

22. Hf & Zf RATIO’s
 = = 0.8 35
SHORE
SHIP
Hf = 28
Hf = 35 Zf Zf

23. SPHERES CAUSE INCREASE IN DIRECTIVE FORCE
WEST

24. N NW NE W E SE SW S

25. 2 = 30 = 0.85 Hf & Zf RATIO’s SHORE SHIP 2 = Ship’s multiplier 35
2 = = 0.85 35
SHORE
SHIP
Hf = 30
Hf = 35 Zf Zf
2 = Ship’s multiplier

26. Hf & Zf RATIO’s SHORE SHIP
Zf REDUCED
TO 30
H.E. corrector ‘RED’ up.

28. Vertical Force Instrument (VFI)

29. Level and heading N – S (magnetic)
V.F.I.
Level and heading N – S (magnetic)

30. Level the needle by sliding the weight
V.F.I.
Level the needle by sliding the weight d

31. V.F.I. Head the vessel E/W (mag)
Remove compass bowl and replace with the VFI in N/S plane
Multiply shore reading by 2 and set the weight to this position on the needle

33. Position the corrector bucket, with corrector magnets installed, at the approximate position.
Mid. Lat = Mid height
Adjust the height of the bucket with the chain until the needle is horizontal

34. FLINDERS BAR INDUCTION
FROM H.E. MAGNETS
RED POLE ‘UP’
FLINDERS BAR
RED POLE ‘UP’
H.E. MAGNETS

35. Masters correction for Heeling Error
Raise / lower the bucket with an increase / decrease of latitude.
Reverse the magnets when crossing the equator and the bucket is at the bottom.
With the bucket at the bottom only the permanent pole below the compass is being corrected for.

36. Voyage changes to HE bucket?
Enroute Fleetwood to Argentina via Freetown

37. Order of placing the correctors
1st – Flinders Bar – as it causes ‘+D’
2nd – Spheres – as they increase the Hf at the compass position
3rd – Heeling Error Magnets – cause a Bp in the top of the Flinders Bar
4th – Permanent correctors - start with the largest Coef. (Bp or C)

38. When should a Compass be checked? (MGN 57)
New build
After structural changes/repairs
After carrying/using Fe cargo or equipment
After a fire
After any grounding or collision
Lightning
Unreliable
Every 2 years*