DP Mini Guide: Redundancy — Worst Case Failure

Crew Connect DP Academy · Mini Guide 08

Redundancy — Worst Case Failure

Topic: Redundancy & Assurance · Sub-topic: WCF / WCFDI  ·  Level: Senior DPO / Master  ·  Read time: 9 min

1. What / Why / How

Redundancy, independence, separation and common mode are the building blocks of a DP vessel's FMEA. Worst Case Failure Design Intent (WCFDI) is a specific, documented, vessel-specific concept — the FMEA describes designed behaviour, but your actual current operational configuration still has to be checked against it.

2. Recognition / Risk / But

Watch for: a degraded redundancy group, a bypassed protection, unavailable equipment, a changed bus configuration, or an untested modification.

But: WCFDI is not "the biggest failure someone can imagine," nor does exceeding it automatically get waved through — it's a defined, vessel-specific boundary, not a loose guideline.

3. Now / What next / Decision / Why

Retrieve the current, correct FMEA/consequence information for this vessel, establish your actual configuration and post-failure capability, apply your activity's controls, and conduct the appropriate risk/escalation process before proceeding.

4. Consequence / Reassess / Escalate

A configuration change moves the credible failure boundary. Identify whether your planned activity can genuinely remain in its current operating mode under the new boundary — don't assume the original FMEA sign-off still applies unchanged.

5. Recover / Verify / Human factor

Restoration includes returning to a documented configuration and completing any required tests/records. Trap: paper compliance — quoting an FMEA without checking its applicability, revision, or the plant's actual current state.

Sources: IMO MSC.1/Circ.1580, IMCA M166 Rev.3 (Code of Practice on FMEA), IMCA M190 Rev.3.2 (DP annual trials), IMCA M103 Rev.5.2. This guide is educational content, not a substitute for accredited DP training, vessel-specific FMEA/ASOG, or full-mission simulator assessment. Crew Connect never infers compliance with a specific vessel's applicable requirements — always verify against your own approved documents.