Mimic avoids catastrophic failure


Shaft alternator
  • A catastrophic failure of a shaft alternator on a 4,000-tonne clean product tanker cost over $90,000 in lost revenue and cost to repair, due to the impact of collateral damage when the alternator failed.
  • The owner experienced additional hidden costs, such as increased insurance deductibles and loss of reputation.
  • Concerned that a repeat of the defect may occur in the future across the fleet, the owner sought a cost-effective monitoring strategy that could predict failures and pre-warn the crew to take mitigating actions.


  • Having conducted a failure modes analysis, James Fisher Mimic (JFM) installed its condition monitoring software and created a monitoring programme, providing actionable insights into the health and performance of vessel machinery.
  • Post installation, Mimic identified noticeable changes to vibration and temperature of an additional deteriorating shaft alternator, warning a failure may occur in 24 to 48 hours.
  • After taking the ship out of service, the shaft alternator was inspected and a loose diode cover was diagnosed. A replacement was installed and the problem was rectified within seven hours, avoiding a catastrophic failure.


  • With performance monitoring, the onset of failure could be identified early and the risk of failure managed, allowing the ship to continue trading with minimal loss of revenue.
  • The investment in Mimic was returned within two months.
  • Ongoing performance monitoring continues to add substantial value to the fleet’s maintenance strategy.

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