Skipper DL850 - CALIBRATION PROCEDURE; Heading Error Correction

Edition: 2017-09-25
Page 51 of 92
Chapter: 5. Calibration procedure
5. Calibration procedure
Speed logs are calibrated in the factory to give reasonable results after installation, however installation
and hydrodynamics vary from vessel to vessel. It is therefore necessary to calibrate speed logs once in
place.
SKIPPER speed logs have two parameters that need to be corrected by calibration.
1. Angular sensor installation error (heading error).
2. Speed variations due to drag or mounting tilt.
1. Heading Error
The heading error parameter corrects for an angular oset in mounting. This oset will result in a
rotation of the measurement axes. The resultant speed will be unaected, but the longitudinal and
transversal components will be incorrect. An oset will result in the vessel typically showing too much
transversal speed, but may also result in speed calibration failing (i.e. initial calibration fails when
further points are added). This oset will show itself as an averaged drift on the calibration.
Reducing Heading errors. Sea valves can be manually adjusted to ensure the sensor is correctly
aligned. Alignment and heading oset are directly connected. To minimize the oset, the sensor should
be mounted pointing ahead.
• Tank mountings have ahead marks on both the tank and the sensor insert.
• Sea valves have a at mark on the port side of the pole (Figure 6.1).
2. Speed variations due to drag or mounting tilt.
Forward
Mounting error (heading error)
A at object points fore/aft.
The at side should be on the port side.
Fig 6.1 Sea valve alignment
DB-2039
Nut M28
DB-2037
Washer (2x)
Gasket
DB-2038
Final Assembly
1. Tighten the Nut M50 (DB-2036). Torque : 98 Nm
2. Push down the Clamp Unit (DB-2033) onto the Nut M50.
and tighten the 2 screws M8 (with lock washer).Torque : 40Nm
3. Screw the 2 Nuts M16 sligtly up to the Clamp Unit.
4. Tighten the 2 Nuts M16 (with lock washer) on
1
2
3
4
Mounting order Nut M50 and Clamp Unit :
the opposite side: Torque : 98 Nm
The Clamp Unit must be fitted on Top of Nut M50
to lock the Nut.
(This is done to give extra security.)
Extention TubeCente Line
Guide Bar Ship
Operation and Installation DL850 270 kHz
SKIPPER Electronics AS