Confidential Human Factors
Incident Reporting Programme
The Charity
Aviation
Maritime
M2271
Initial Report
A 70-meter superyacht was anchored in a very ‘tight’ anchorage with limited swing circle and depth. There was around 3 meters of depth under the keel, and the swing radius was 130m (160m would have put the vessel aground)
With some bad weather expected, the master decided to put two anchors down. Once the weather cleared, both anchors remained deployed.
When the anchors were retrieved a few days later, both anchor chains were severely twisted and the crew had spent more than 12 hours trying to free them – all the while slowly dragging towards the shallows nearby.
More bad weather was forecast so a decision was taken to release both anchors from their bitter ends to prevent the vessel from grounding. Once both anchors were released, the vessel made its way to port before the weather closed in and a salvage company later recovered the anchors and returned them to us a few days later.
CHIRP Comment
Anchorage locations should continuously be assessed for proximity to known hazards, including under-keel clearance and potential grounding, safe swinging distance from other nearby vessels, and holding ground capability in inclement weather.
Although vessels will generally anchor close to the shore for their passengers’ convenience, vessels should be ready to move to a deeper anchorage if the vessel’s safety cannot be assured. In this incident the vessel was anchored only 30 meters from a lee shore. Given the expected weather forecast, this was an unacceptable and unnecessary risk.
Using two anchors when expecting bad weather can help to control the vessel’s yaw but should be considered a temporary measure only, because of the heightened risk of them being fouled. As soon as the reason for deploying the second anchor has passed, it should be weighed and brought home. An anchor home ready for an emergency is good contingency planning.
Key Issues relating to this report
Capability—Does your bridge team have the necessary knowledge and training to understand and appreciate the use of the ship’s anchors? Given the proximity to the shore and other vessels in the anchorage, a vigilant bridge anchor watch is required. What does your SMS advise on anchoring operations?
Teamwork– Continually review whether the second anchor is required, and weigh the second anchor when the original reason for using two anchors is no longer required.
Situational Awareness– While at anchor, a member of the bridge team should periodically visit the fo’c’stle to monitor the growth and stay of the anchor chain (or chains) so that issues can be identified early – ie before the chains become twisted.
Alerting—If you were in a similar situation, would you alert the master that the other anchor should be brought home so it can be used in an emergency?