Boston Whaler 37 Justice Series, Operation & Maintenance Manual

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4-9
Boat Systems Section 4
Magnetic Comp ass
All magnetic comp asses are sub ject to magnetic
interference, which can p roduce errors called
deviation. Comp ass deviation can contrib ute
to inaccurate course plotting and position es,
p lacing your crew, your b oat, and others at risk.
Deviation
The loca tion of your co mpass has been select ed to
minimize deviation ca used by other eq uipment installed
on the boat. M agnets, ferrous metals, and cu rrent-
ca rrying device s are co mmon ca uses of deviation. The
co mpass is also loca ted just below the operator’ s line of
sight so it ca n be easily read during normal operation.
P eriodica lly ch eck the alignment of the co mpass to
verify that it is installed properly and co mpensated.
Compensation is the act of co rrect ing for deviation.
Refer to the manufact urer’ s literature for detailed
information about the co mpensation proce dure.
V ariation
It is important to understand that magnetic co mpasses
point toward magnetic north. There is a difference
between magnetic north and true north. That difference
is ca lled variation. V ariation differs depending on your
geographica l loca tion and ca n be determined by referring
to a loca l ch art.
WARNING