Poles beneath the compass position

Coefficient JIt is the mathematical representation of deviations heeled 1degree to port and 1degree to starboardDefinitionIt is the difference in deviation between that when the ship is upright and that when the ship is heeled on the same course.

1st causeSHIPS PERMANENT VERTICAL FIELDBLUE UP - HIGH SIDED H.E.

1st cause - SHIPS PERMANENT VERTICAL FIELDMaximum on North & South courseNil on East & WestSemicircularSimilar to Coef CNot affected by latitude

2nd causeINDUCED VERTICAL SOFT-IRONBLUEUP - HIGH SIDED H.E.

2nd cause - INDUCED VERTICAL SOFT-IRONMaximum on North & South courseNil on East & WestSemicircularSimilar to Coef CChanges with latitude and magnetic hemisphere

3rd causeVERTICALLY INDUCED HORIZONTAL ATHWARTSHIPS SOFT-IRONNORTHERN HEMISPHEREHIGH SIDED H.E.

COMPENSATION WITH SOFT-IRON SPHERES3rd cause

NINDUCED F&A HORIZONTAL SOFT-IRONTERMINATING BELOW COMPASS4th cause

INDUCED F&A SOFT-IRONTERMINATING BELOW COMPASSNORTHERN HEMISPHERELOW SIDED H.E.HEADING NORTH4th cause

HEADING EAST/WESTERROR = NILTERMINATING MATERIAL BELOW COMPASS

Heeling ErrorCorrection

Hf & Zf RATIOsSHIPSHOREHf = 28ZfHf = 35Zf = 28 = 0.8 35

WESTSPHERES CAUSE INCREASE IN DIRECTIVE FORCE

NNENWWESSESW

Hf & Zf RATIOs with the Spheres in placeSHIPSHOREHf = 30ZfHf = 35Zf2 = 30 = 0.85 352 = Ships multiplier

Hf & Zf RATIOsSHIPSHOREHf = 30Zf REDUCED TO 30Hf = 35Zf = 35H.E. corrector RED up.

Vertical Force Instrument (VFI)Magnetic NeedleWeightSpirit LevelPivotGraduations

Vertical Force Instrument (VFI)

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

V.F.I.dLevel the needle by sliding the weight

V.F.I.Head the vessel E/W (mag). This eliminates the 4th cause of HERemove the compass bowlMultiply shore reading by 2 and set the weight to this position on the needlePlace the VFI in N/S plane where the compass bowl would sit

Position the corrector bucket, with corrector magnets installed, at the approximate position.Mid. Lat = Mid heightAdjust the height of the bucket with the chain until the needle is horizontalHeeling Error is now corrected for that latitude

Masters correction for Heeling ErrorRaise / 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

FLINDERS BAR INDUCTIONFROM H.E. MAGNETSRED POLE UPH.E. MAGNETSRED POLE UPFLINDERS BAR