This incident summary is based on an investigation report highlighting a dragging anchor event involving a general cargo vessel that led to collisions with two other nearby vessels. The report examines the sequence of events, contributing factors, and safety lessons to help prevent similar occurrences.
What Happened
A general cargo vessel in ballast condition was en route to an anchorage for bunkering, operating under a Condition of Class (CoC) that required its main engine to remain on standby while at anchor due to the loss of its port anchor in previous heavy weather. On arrival, deteriorating weather led to the cancellation of the planned bunkering, and the vessel was instructed by Vessel Traffic Services (VTS) to proceed to another anchorage. Before departing, the master noted that the ship had already dragged anchor.
At the new anchorage, the pilot advised the master to remain vigilant and keep the engine on standby. Shortly after the pilot disembarked, the master stopped the engine and delegated anchor watch to the second officer without providing detailed instructions on weather monitoring. During the second officer’s watch, the vessel began dragging anchor towards a nearby research vessel. The movement went unnoticed for several minutes. Once detected, efforts to start the engine and avoid collision were delayed, and despite the use of the bow thruster, the vessel’s stern collided with the bow of the research vessel.
Both vessels became entangled due to the anchor chain and, under wind and tidal influence, drifted towards another anchored vessel. Attempts to disengage were unsuccessful, resulting in a second collision between the general cargo vessel and the third vessel. All three boats sustained structural damage, but no pollution or injuries occurred.
Why It Happened
The incident occurred due to a combination of operational, procedural, and environmental factors. The bridge anchor watch handover was incomplete, lacking essential details on position‑monitoring intervals and the need to observe changing weather and tidal conditions. This, combined with the second officer focusing on administrative tasks instead of continuous position checks, led to a delayed detection of the anchor dragging. The master’s decision to stop the main engine, despite a Condition of Class requiring it to remain on standby, significantly increased response time once movement was detected.
Established anchoring procedures, such as having the anchor party ready, deploying additional cable, and promptly notifying nearby vessels or VTS, were not followed. Communication lapses further compounded the problem, preventing other ships from taking early precautionary measures. Inconsistent guidance within the Safety Management System regarding main engine readiness allowed varying interpretations across the fleet, leading to different operational decisions under similar conditions. Adverse environmental factors, including strong wind and tidal stream, contributed to the anchor dragging and made recovery operations more difficult.
Actions Taken
Following the investigation, several corrective measures were identified. Enhanced watchkeeping practices were recommended, including more frequent position monitoring and the use of GPS anchor alarms to detect dragging at the earliest stage. Anchoring procedures should require immediate reporting to the master, preparing the main engine without delay, and ensuring adequate bridge manning, including a helmsperson and lookout when necessary.
The Safety Management System should be updated whenever a Condition of Class or other temporary operational restriction is imposed, providing unambiguous guidance on engine readiness and crew responsibilities. Training programs should place greater emphasis on risk assessment, communication protocols, and standardised operational responses to ensure consistent practices across the fleet, particularly when operating in congested anchorages and adverse conditions.
Lessons Learned
- Maintain main engine readiness when required by class conditions or adverse weather forecasts.
- Ensure clear and complete watch handovers, including position-monitoring frequency and environmental condition awareness.
- Implement standardised anchoring procedures, including immediate reporting, anchor party readiness, and informing nearby vessels.
- Use GPS anchor alarms and conduct regular position checks to detect dragging early.
- Strengthen company SMS to clarify engine readiness and operational response in adverse conditions.
- Emphasise training on risk assessment, communication, and emergency preparedness to ensure consistent fleet-wide practices.
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Source: BRITANNIA P&I CLUB
