Survey & Positioning Services


MOD use C-NAV 2050 dual-frequency GPS receivers and compact L1/L2 tri-mode antennas for our general offshore positioning requirements.  These units comprise a 22 channel precision GPS sensor with two additional channels for receiving Satellite Based Augmentation System (SBAS) correction signals, along with an L-Band demodulator permitting reception of the world-wide decimetric-accuracy C-Nav Starfire Real Time Gipsy network correction service.  Typically we use C-NAV GPS in conjunction with our purpose-designed MOD rigmove navigation software “Rigpro-Semi”.

Other uses of the C-NAV dual-frequency receivers include precise post-processed positioning and heighting of offshore fixed structures.

At the end of rig-moves, for the determination of final rig position, MOD deploys its own purpose-designed logging and transformation software “Final Fix”.

The company has built its own tug management system “Vpod”, which comprises a Vector dual-antenna GPS Gyrocompass to obtain the tug’s position and heading combined with a two-way telemetry unit. Up to four “Vpods” may be used simultaneously and are controlled from the rig via the “RigPro-Semi” program.  In addition to transmitting the position of the anchor tugs for display on the rig’s “Rigpro-Semi” monitor screen, the “Vpods” also send quality data. On the tug, the “Vpod” unit provides the captain with an auto scaling monitor, showing his real-time position relative to the rig, the surrounding infrastructure and his assigned target i.e. buoy/ anchor drop point.

MOD use pc-based MEL scanning sonars temporarily located on rig legs or the drill-string for identification of seabed well structures or quick inspection of the seabed for large debris or obstructions.


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