Search

Reliable performance is the key requirement for instruments used in offshore moored buoys for cyclone monitoring, as under performance of the sensors can have a serious impact on the societal protection, and in addition, lead to costly repair and reinstallations. The instrument selection and application practices are based on the experiences of the global scientific community, and their performances are monitored based on IEC61508 standards. Reliability modeling based on experiences in the operation and maintenance of moored surface buoys for approximately two decades has identified that the sensor suite used for cyclone monitoring has a Mean Time Between Failure of 0.6 years, which is the basis of the implemented reliability centered maintenance strategies. As this is the first attempt to study the performance of such moored buoy instruments which have cumulatively clocked more than 7.3 million demanding offshore instrument-hours, the data presented shall serve as input for the offshore environmental instrument system design.

This paper describes the Advanced Data Reception and Analysis System (ADDRESS) used for monitoring Indian Ocean moored buoys and the reliability analysis done on the data reception and dissemination performances. The system needs to be highly reliable, as the critical real-time data received from the tsunami and meteorological buoys are used for societal protection decision support systems during tsunami and cyclonic events. Driven by demanding societal needs, the developed ADDRESS with a 24/7 manned and automated Mission Control Center and the implemented system integrity proof test interval is found to conform with the IEC 61508 SIL 4 safety and reliability levels and to have an availability of 99.9938%. The graphical display capabilities developed are used for buoy deployment support, early restoration of failed moorings, and for up-keep of system components operating in remote harsh offshore environments by monitoring their performance over time.