Kongsberg EM 710, Installation Manual

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Kongsberg EM 710
If there is any point in the fore-aft direction which does not
change height with respect to the water line with changes in
vessel speed, this will be the ideal location for the motion sensor
as it will eliminate any errors from squat induced height changes
which is not measured by current motion sensors.
8.3.2 Heading sensor
This sensor can either be based upon:
• GPS measurements like Seapath 200 or POS/MV
• Fibre optic gyro compass
• Standard gyro compass
The heading sensor dynamic accuracy should be in the order
of one third of the transmit transducer beamwidth or better (i.e.
0.3º for a 1º beamwidth).
The sensor must be aligned to the vessel centre line to provide an
accuracy better than a fifth of the transmit transducer beamwidth
(i.e. 0.2º for a 1º beamwidth).
Compasses sensitive to acceleration should be mounted close to
CG (Centre of Gravity)
Please see the sensor installation manual for any further
instructions on installation and alignment.
The output of the sensor must be verified with the vessel having
a known heading such as when it is in drydock. Alignment
accuracy can also be evaluated with the vessel tied (in opposite
directions) along a quay with known heading. A calibration
survey should afterwards be performed at sea to confirm correct
performance.
8.3.3 Positioning system
Most positioning systems are today based on Global Navigation
Satellite System technology (GNSS) such as GPS, GLONASS
and/or (later) GALILEO. The location of the positioning system,
antenna must be measured, including its height (if geoide height
is a measured and used parameter). It should be noted that some
GNSS based systems use two (or more) antennas to provide
vessel heading, if so the installation manual for the system should
be consulted for how these antennae are to be aligned and how
accurately the location of the antennae need to be measured.
8.3.4 Water line
With the vessel in normal trim, i.e with an indicated pitch angle
of zero from the motion sensor, the distance to the waterline
may be measured anywhere on the vessel. Otherwise it must be
measured at the alongship physical location of the motion sensor.
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