B&G HS2000 - Manual (Page 39)

HS 2000 User Manual
Part 3 - Calibration
HB-0846-03
3-3
PART 3 - CALIBRATION
3.1 INTRODUCTION
WARNING - Every care must be taken when undertaking any
calibration procedure to ensure that the HS 2000 System is
calibrated accurately and correctly. Incorrect calibration could
lead to incorrect navigational information.
Calibration of an integrated instrument system is one of the most
misunderstood processes. Good instruments badly calibrated will
achieve very little. This part of the manual provides simple
instructions, which, when carefully undertaken in the correct order,
will consistently produce satisfactory results.
There are four basic inputs to your system that are fundamental to
the integrated approach: boat speed, compass heading, depth and
sea temperature.
These four basic inputs must be correctly calibrated before the
values of greater interest can be derived. On any boat the
calibration of these items should be high on the list of task
priorities following the launch. Finally, it is crucial to keep a full
record of the process.
3.2 BOAT SPEED/LOG CALIBRATION
3.2.1 Principle of Log Calibration
To calibrate the log it is necessary to ascertain the number of
revolutions of a paddle-wheel, or sonic blips per second, that
correspond to each knot of boat speed. The boat speed/log
calibration value is always shown as Hertz/knot (Hz/kt).
3.2.2 Preparation for Log Calibration
Before calibrating the log you should ensure that the speed sensor
unit is correctly aligned as follows:
Paddle-Wheel - The moulded arrows on top of the unit
must be pointing forward along the fore and aft line of the
hull. The unit must also be completely free of any weed
or other fouling.
Sonic Speed - Check that the unit is operating correctly
as per the owner's manual.