The value of learning from other people’s experiences is obvious from a new publication from IMCA – the International Marine Contractors Association. Their “Analysis of Station Keeping Incident Data 1994-2003” is an analysis of IMCA dynamically positioned (DP) station keeping incident data over the ten-year period. The analysis extends the work that the trade association carries out on an annual basis to help determine trends and provide more detailed analysis on underlying causes.

The direct benefit of DP incident reporting, with all its implications, is that it keeps to the fore the acceptance that incidents do happen. This helps establish trends in incidents for discussion with vessel operators, equipment suppliers, training establishments and others to address particular issues. It also shows that catastrophic consequences from loss of position do not happen if the incidents are managed well. This is something of a sweeping statement, but it is reasonable to claim that if incidents were not in the open and discussed, management may at some point not give the solving of DP problems the resources they need and vendors would not have the motivation for improvement.

The new report draws some fascinating conclusions:

• For example the number of incidents caused by thrusters’ failure is high, especially when all the rules since the advent of DP are written to prevent the failure of a single thruster causing a loss of position. However, a closer examination of this shows that none are from frequency drives and this has been a major advance for DP vessels.
• Blackouts and partial blackouts have continued to occur even with advances in generators, switchboards and power management systems. However the number of incidents and the number of vessels using DP has increased over the last ten years and this could be why the number of blackouts (full and partial) reported has increased, combined with the fact that very few DP vessels have been scrapped. Nevertheless, there is a definite step change increase in the database between 1999 and 2000, perhaps due to receiving more reports overall that year.
• A single thruster causing a loss of position dominates the percentage of incidents triggered by thrusters, even though DP rules and guidance have been written to prevent the failure of a single thruster causing a loss of position. Thruster failures causing a loss of position are not decreasing.
• Cable/pipelay vessels are more likely to suffer from DP computer software triggers due to their DP software being designed more for holding position than track-follow.