2021-06-24
Page 27 of 38
CU-M001 User manual
Calibration, Speed
The DL2 system measures 2 parameters; Speed Over Ground (SOG), and Speed Through Water.
Both these need calibrating , and calibration values may be slightly different for each. SOG can
be calibrated in two ways. (manual and sea test). Once correctly calibrated, the system will use
the secondary sensors to ensure that any small devaitions from the main calibration of speed
are compensated. This results in a stable calibration set , that should not require adjustment.
STW should be calibrated by sea test. But temporary values can be entered using the manual
calibration methods.
The
approved way
of speed calibration is performed by sailing on opposite courses to get an
accurate value. This is performed in a ’SEA TEST’ It is typical that the user may perform a manual
calibration in the period before a sea test. This can be performed with the aid of GPS ( if available)
or manually by entering the known speed from a GPS and the current measured speed.
Step 2a. Manual speed calibration/adjustment:
The user enters speed values directly into the calibration table by comparing to other equipment,
such as GPS. This can also be used to adjust values. The calibration table is split into five ‘real speed’
zones. It is not possible to calibrate more than one point within each zone. It is important that at least
one high speed zone is calibrated, however the other zones will automatically adjust if they have not
been calibrated before. The scale of the real speed on the table is set by the maximum speed of the
vessel. This and other important parameters can be entered in the DL2 setup menu.
To use the GPS calibration, a GPS Speed signal must be connected to the systems input (Either
via ‘NMEA (IEC61162-1) or LAN (IEC61162-450). This is recomended. The GPS speed information
will be used as a quality control throughout the system. Sail the vessel within the speed limits of the
zone to be calibrated, and when sailing at a stable heading and speed, in a low current area. Press
the use current. The current GPS speed value will then transfer to the cuurent zone within the table.
To manually adjust the calibration point, select
the ‘Manual calib’ button. Use the buttons on
the right to select a speed zone and then enter
the speed value displayed that is measured by
the system, and the actual current speed.
Each calibration zone can have 3 points.
Manual, typed in value
Sea Test, Calibrated by 2 leg sea test
Default. No calibration is entered in this point so
the system works out the most likely based on
the other pioints.
The point in use can be selected using the lower
button on the right.
