2021-06-24
Page 25 of 38
CU-M001 User manual
N
S
E
W
Speed of water
Mounting offset
F
orward
Ship
Ship
(
seen from above
)
Calibration parameters
Calibration. Installation angle
A DL2 is measuring speed speed through water (STW) and speed over ground (SOG) in 2 axis.
Longitudal and transversal.
For correct longitudal and transversal measument the sensor needs to know forward direction of
the vessel. This is done during installation by aligning sensor forward point with vessel forward
point.
Any mounting offset will result in a rotation of the measurement axes (Installation angle). The
resultant speed will be unaffected, but the longitudinal and transversal components will be
incorrect. An offset will result in the vessel typically showing too much transversal speed, but may
also result in speed calibration failing.
Measuring Installation angle
A software measument of installation angle is only possible on 2-axis (long transversal)
speed logs such the DL2.
The installation angle measurement must be performed when the vessel is in steady speed and
steady heading in calm waters.
Please note that all installation angle measurements when vessel is in zero or around zero knot
will be only noise.
Reducing Heading errors
.
The sensor forward position can be physically manually adjusted in the sea valve. To minimize the
offset, the sensor should be mounted pointing ahead.
See installation manual for procedure.
Installation angle >10deg should be corrected by physical adjusting the sensor forward alignment
in the sea valve.