Page 44: of Marine Technology Magazine (November 2013)

to the marine forensic investigation of any offshore incident  Ocean current ? Surface currents can impact on any of oad-ing operations from the FPSO to the shuttle tankers and in-  uence the response of the risers and moorings, resulting in fatigue loads  Position and attitude ? measurement of the position of the FPSO is essential in storm periods to understand the vessel response to environmental forcing and the coupling of the re- sultant fatigue on risers and mooring lines. The position of the vessel is also critical in the assessment of any marine incident  Riser monitoring - a detailed understanding of the environ- mental forcing to the FPSO combined with the riser response can aid the design process and provide the input to fatigue calculations.  Hull monitoring ? stress induced in the deck and hull of an FPSO can be monitored using a series of long base strain gauges positioned in strategic locations on the deck and  are tower. In addition, pressure sensors installed in the hull pro- vide information on the vertical acceleration of the FPSO  Mooring line ? monitoring the mooring line is challenging and there is a scarcity of long-term in-situ observed data sets for mooring line tension. For forensic engineering and valida- tion of design codes, it is essential that mooring line tension is collected simultaneously with metocean parameters on a com-mon time base.Each of the components mentioned above are likely to in- volve a number of third party suppliers, therefore the chal- lenge that oil and gas majors are faced with is ensuring they all integrate into one effective monitoring system, to provide a holistic approach and support the assets? integrity manage- ment program. Correct placement of the sensors on board the FPSO and full integration of the data within a common time base is vital. By carefully setting up the sensor clocks and sampling frequency during the installation of sensors at stra- tegic locations on the FPSO, companies can use the resultant data set to effectively study the coupled response of the vessel with the environmental and resultant dynamic loading on the risers and mooring lines to study fatigue. Monitoring of all the different parameters within this com- mon time base can also assist with forensic investigations of marine incidents. For example, companies want to be able to match the time O shore Inspection, Repair & Maintenance ADCP Deployment November/December 201344 MTRMTR #9 (34-49).indd 44MTR #9 (34-49).indd 4412/13/2013 9:59:26 AM12/13/2013 9:59:26 AM