Question 1

What is the purpose of a Failure Mode and Effects Analysis (FMEA) for a DP vessel, and who mandates it?

Accepted Answer

The FMEA is a class-required document that systematically analyses each identifiable failure within the DP system and proves, by showing which failures are tolerable without loss of position, that the vessel has the redundancy claimed for its class notation Classification societies (DNV, Lloyd's, Bureau Veritas, etc.) require an approved FMEA as part of the DP class notation process. It is the engineering document that demonstrates the redundancy architecture actually delivers what the class notation claims — for DP2, for example, proving that any single failure leaves sufficient redundant systems to maintain position.

Question 2

Who is responsible for commissioning a DP FMEA, and who approves it?

Accepted Answer

The shipowner/operator commissions the FMEA, prepared by a specialist firm; it is reviewed and approved by the classification society as part of DP class certification An FMEA is a specialist engineering document, typically prepared by the DP system manufacturer, a marine engineering consultancy, or the vessel's designers. It must be reviewed and stamped by the classification society before it forms part of the vessel's class certification. It is not a document the DPO or vessel crew can prepare themselves.

Question 3

What are FMEA Proving Trials, and how do they differ from an annual DP trial?

Accepted Answer

Proving Trials are live tests that physically trigger each failure mode listed in the FMEA to verify the FMEA's predictions are correct — they are conducted once at class certification and after major modifications; annual DP trials test system functionality and WCF in operational conditions but do not re-verify the FMEA Proving Trials witness the actual failure modes in a controlled environment to validate that the vessel behaves as the FMEA predicts. They are a one-time event at class certification (and after major changes), not a recurring check. Annual DP trials (per IMCA SEL 019 / M252) are periodic operational readiness checks — they test whether the DP system works, not whether the FMEA predictions remain accurate.

DP — FMEA Trials Practice Questions