Question 1

During a DP2 watch on a construction vessel, Thruster 3 throws a fault alarm and the DPO focuses intensely on diagnosing and resetting the thruster. While the DPO is working on the fault — eyes on the thruster control panel — the vessel's position begins to drift 3m, then 5m, then 7m to the north. The yellow position alert sounds, but the DPO acknowledges it and returns to the thruster fault without registering the position trend.

What human factor is operating, and what structured habit prevents it?

Accepted Answer

Tunnel vision — the DPO became task-focused on the thruster fault and lost situational awareness of the vessel's overall state. The habit that prevents it is a periodic structured scan: every 60-90 seconds during any alarm response, the DPO must deliberately break from the fault diagnosis and check position, heading, all reference systems, and the overall DP status before returning to the fault Tunnel vision during fault management is one of the most documented human performance failures in DP operations — IMCA incident reports consistently describe DPOs who were fully engaged in resolving one alarm while an unmonitored developing situation overtook the vessel. A single thruster fault is manageable; a thruster fault plus an undetected 7m position drift approaching a structure is an emergency. The counter-habit is explicit and must be trained: force a scan of the entire DP status picture at regular intervals during any fault management period. A 7m drift developing over several minutes produces multiple alarm signals — acknowledging them without actually reading them is the failure mode.

Question 2

A DP2 pipe-lay vessel has been exceeding its ASOG yellow wind limit by 2–4 knots on every watch for the past five days without incident. The lead DPO tells the incoming watch: 'Don't worry about the yellow alarm — it goes off in these conditions all the time and we just carry on. The old limit was too conservative anyway.'

What is the danger in the lead DPO's reasoning?

Accepted Answer

Repeated limit exceedance without incident is the definition of normalisation of deviance — each incident-free violation makes the next seem safer, eroding the original safety margin without any formal review. The ASOG limit exists because someone calculated the risk; overriding it verbally on the basis that "nothing happened" removes the agreed safety envelope without authorisation IMCA's 2024 Station Keeping Review identified normalisation of deviance as one of the most persistent human factors in DP incidents. The ASOG limit has not become less relevant because the vessel survived exceeding it five times — the safety margin has simply been eroded on each occasion without a formal risk assessment supporting that decision. If conditions deteriorate slightly further on the sixth day, the vessel may be operating at actual capability limit with a DPO team who believe the alarm is background noise. The correct action is to formally review the ASOG with the client, not to informally dismiss the threshold.

Question 3

A DPO is six hours into a twelve-hour DP watch on a cable-lay vessel. Conditions have been perfect all watch — flat calm, three good references, all systems green, no alarms. The DPO begins browsing the internet on a personal device to pass the time.

What human factor is operating here, and what is the specific risk it creates in DP watchkeeping?

Accepted Answer

Extended uneventful periods create the highest complacency risk in DP watchkeeping: the DPO's vigilance degrades precisely because nothing has demanded it. When a fault develops — a reference dropout, a thruster fluctuation, a slow position drift — the response time increases because the DPO's attention is elsewhere. Long periods of routine are when the first small signals of developing problems are most likely to be missed Complacency in long uneventful DP watches is one of the top human factors identified in IMCA incident data. The paradox is that the safest-seeming watches — calm conditions, all systems green — are when the DPO's monitoring vigilance is most degraded. DP incidents are not always sudden; many develop over minutes through progressive reference degradation, slow position drift, or incremental power system changes. A DPO whose attention is on a personal device during this development window misses the early signals that would allow a controlled response. Active, structured monitoring — regularly checking reference quality, gyro agreement, thruster load, position variance — maintains the vigilance that automated alarms cannot replace.