Sperry Marine 4914-CA, Operation, Installation And Service Manual

Page: 100 / 192

MRSPQPLc k^sfd^q u jh N
TJNM j~ÖåÉíáÅ=`çãé~ëë=`~äáÄê~íáçå
TKT j~ÖåÉíáÅ=`çãé~ëë=`~äáÄê~íáçå
Ideally, the magnetic compass heading displayed at the
NAVIGAT X MK 1 would exactly match the indication of the steering
magnetic compass (at a given mag. variation of 0.0°).
In practice, however, deviations will occur between the steering mag-
netic compass heading and the heading data transmitted by a fluxgate
sensor of a magnetic compass or an electronic compass, as displayed at
the NAVIGAT X MK 1.
The NAVIGAT X MK 1 automatically corrects such deviations if a calibra-
tion table has been stored and calibration is activated in the User Setup.
`~äáÄê~íáçå=mêçÅÉÇìêÉ=lîÉêîáÉï
The magnetic compass calibration is a two-step procedure:
• At first, the existing deviations between the indication of the steering
magnetic compass and the magnetic compass heading displayed at
the NAVIGAT X MK 1 must be determined. This requires that the ves-
sel is swung very slowly through a full circle so that for each 10° of
magnetic compass heading (0, 10, …, 350°) the corresponding dis-
play value is obtained.
• Secondly, the resultant correction values are calculated and entered
into the magnetic compass heading calibration table of the
`^rqflk
Risk of inaccurate magnetic compass calibration
The magnetic compass heading calibration corrects deviations due to the
combined effects of the magnetic environment, the particular sensor
being used and the receiving circuitry on the master PCB.
Therefore, a new calibration must always be carried out when:
- the steering magnetic compass is exchanged or newly adjusted,
- the magnetic compass heading sensor is exchanged and,
- when the master PCB is exchanged, in case a fluxgate sensor is used.
Never use a true heading source, e.g. a gyrocompass, as the calibration
reference.
Never attempt to correct residual deviations of a properly adjusted mag-
netic compass by means of the calibration table.
kçíÉ The Magnetic Compass Calibration Table shall only be switched on for
automatic magnetic compass heading correction in case a magnetic
compass is indeed connected to the NAVIGAT X MK 1 system via a flux-
gate sensor.
kçíÉ If magnetic compass heading is received from an already calibrated
source, such as a NAVITWIN, NAVIPILOT or a self-calibrating electronic
compass, magnetic compass calibration at the NAVIGAT X MK 1 is not
required and must be disabled.
`^rqflk Risk of inaccurate magnetic compass calibration
The magnetic compass used as the calibration reference must be prop-
erly installed and adjusted.
The procedure should be carried out in calm seas only.