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

Heeling Error Poles beneath the compass position

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

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

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

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

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

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

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

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

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

Heeling Error Correction

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

SPHERES CAUSE INCREASE IN DIRECTIVE FORCE WEST

N NW NE W E SE SW S

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

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

Vertical Force Instrument (VFI)

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

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

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

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

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

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.

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

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)

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*