Vessel Coordinate System - Kongsberg EM 122 Installation Manual

alignment
After the installation is completed in dock, a full set of alignment measurements must
be carried out. This job has to be done by professional and experienced land surveyors,
typically equipment is electronic total stations. Kongsberg Maritime can not be expected
to have qualified personnel for such work.
The results, with all measurements taken in a common vessel coordinate system, are to
be entered in the EM 122 Operator Station.
NB! Some external sensors may have been set up to output data referred to a location
that differ from where it is physically mounted. It is the x, y, z values for this location
that must be entered into the EM 122 Operator station.
Note
The given accuracies in the tables in this chapter, are maximum values, and if easily
achievable, better accuracies should be obtained. The relative heading accuracy
between Rx and Tx must be within ±0.1º.
All distance measurements are to done to an accuracy of 5 cm both horizontally and
vertically.
The procedures and requirements made by the manufacturers of the external sensors
connected to the EM 122 must also be taken into account.

Vessel coordinate system

A Cartesian coordinate system must be defined for the vessel. The following definition
must be adhered to:
• X = forwards
• Y = to starboard
• Z = pointing downwards
There is no restriction on where the coordinate system's origo is located.
Note
The sea surface with the vessel in normal trim defines the horizontal (X-Y) plane. The
water line should therefore be marked on the hull with the vessel in normal trim before
dry docking for installation of transducers.
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