Kongsberg EM 2040 MKII, Installation Manual

Page: 151 / 248

472405/A
151
About dimensional surveying and alignment
The EM 2040 MKII Multibeam echo sounder is a precision instrument for high quality
data collection.
In order to obtain precision data that are both detailed and correct, it is necessary to
align the transducer, measure the location and offset of each sensor in relation to the
vessel’s coordinate system, and calibrate the complete EM 2040 MKII prior to use.
Modest accuracy requirements apply when your EM 2040 MKII system is only used to
investigate objects in the water column.
The quality assurance tasks required for EM 2040 MKII include:
• Aligning the transducer during installation
• Dimensional surveying
• Calibration
The alignment and dimensional surveying must be done during the EM 2040 MKII
installation with the vessel in dry dock. The first calibration is normally done at sea
during the Sea Acceptance Test. This calibration may not be complete, and must then
be repeated later. The calibration is then repeated at regular intervals, and prior to each
survey.
Dimensional surveying
Determining the relative positions and orientations of the sensors and the transducer with
high accuracy is important. This can only be met using a survey company/personnel
with good experience in maritime dimensional surveying.
The dimensional surveying tasks required for the EM 2040 MKII system include:
1 Define the vessel coordinate system.
2 Define the location of the origin in the coordinate system.
3 Define the waterline with reference to the origin of the coordinate system.
4 Set out the required coordinate reference points throughout the vessel.
5 Define the vessel’s centre line.If required, identify the line with physical markings.
6 Measure the physical location and installation angle of all relevant sensors (or
sensor antennas).
7 Measure the physical location and orientation of the transducer. Place it in the
coordinate system.
All results from the dimensional survey measurements must be summarized in a report
by the survey company doing the work.
The information provided by the dimensional survey is entered into the EM 2040 MKII
software as installation parameters.
Dimensional surveying and alignment