26
47_processor_Regatta_um_UK_40
The calibration adjustment is:
9
.
0
2
0.92
+
0.88
=
Calibration using SOG as the reference:
With this method you need to motor at ten knots on two consecutive runs at opposite
headings (in order to eliminate the effect of the current). Both runs must be of equivalent
distance. SOG from the GPS will be the reference speed. The calibration adjustment will
be the result from averaged boat speed and averaged Speed Over Ground.
The calibration adjustment value can be calculated from the data logged in the internal
USB key. Useful data will be extracted for use with the formula below. Navigation software
which features a boat speed calibration tool can also be used.
Useful tip:
If the boat’s system has two ultrasonic sensors connected to an Interface Dual, you can
proceed as follows:
The calibration adjustment value will be entered for each sensor by identifying the correct
side and by forcing the heel with an offset greater than 3° for each. Heel values are
negative on the Multigraphic or Multidisplay for a starboard side heel.
Menu
►
Sensors
►
Boat speed
►
Calibration
8.5.1 Linear boat speed response against boat’s heel angle
Modern monohull designs such as the Open 60, with flat bottoms and a hard chine, have
a wetted area where the longitudinal axis is different when heeling (such as a catamaran
with asymmetric hulls). Therefore the speed sensor cannot be aligned correctly when the
boat is flat or heeling. You may have to adjust the boat speed against the heel angle.
For that purpose, a table « BtSpdHeel.txt » is available in the Processor Regatta at the
following address:
ftp://root:[email protected]/mnt/flash/processor/tables
It can also be accessed from the home page by pressing the « Calibration » button, and
further the « Boat Speed vs Heel » button.