MAIB Issues Safety Warning on Laid Up Cruise Ship Anchor Failures

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The UK’s marine accident investigation branch (MAIB) has become concerned at the number of recently reported marine incidents involving cruise ship anchor systems failures and has published a safety bulletin to bring the issue to the attention of the cruise industry and to highlight the lessons that can be learned to prevent future incidents.

Cruise vessels anchored

The COVID-19 enforced operational pause saw many cruise vessels anchored off the UK’s south coast. During this period, there were several anchor losses associated with the inclement weather over the autumn and winter and the use of the anchoring equipment beyond its intended design parameters.

Failures have occurred in joining links, anchor chain common links, D-links and across the anchor crown causing the fukes to be lost.

Of the failures reported so far, the most frequent has been the failure of the joining links connecting two shackles of cable, often when a significant amount of cable was out, in some cases as much as 11 shackles on deck.

Although the additional weight of the cable can prevent the vessel from dragging anchor, in adverse conditions it will also increase the forces acting on the cable and anchor.

When combined with the significant yawing caused in high winds, and cable lying unused in a chain locker since the last time it was end for ended, it is unsurprising that several anchor equipment failures have occurred.

The issue is further exacerbated when the scope of cable remains constant, causing a single point of loading and wear, for example, where the cable is in contact with the hawse pipe. The indications are that anchor equipment has been failing due to operational issues rather than fabrication defects.

Safety issues

  • ship’s masters should be proactive in heading to sea and not wait for the anchor to drag in strong winds before acting
  • the choice of anchor and amount of cable chosen should be varied to avoid single point loading
  • ship’s masters should ensure they and their crew are aware of the reporting procedures to the coastal state in the event of losing an anchor
  • the anchoring equipment should be assessed before returning back into normal service due to the greater use of the anchors during this extraordinary period.

Lessons learned

  • Operational limits for anchoring must be sufficiently cautious to ensure the weighing anchor is not left too late, risking overloading anchor equipment. If strong winds are forecast, proactive action should be taken to seek a more sheltered anchorage in good time or proceed to sea and ride out the weather. Do not wait until the anchor drags or until most of the anchor cable has been paid out before weighing anchor.
  • Steps should be taken to minimize the wear on the anchoring equipment as far as possible. When the opportunity presents itself, the anchor in use should be rotated and the scope of cable varied on a regular basis to minimize single point loading. An appropriately experienced crew member should also carry out regular checks on the windlass brake condition and areas where the cable is in contact with the ship.
  • While at anchor for significant periods, ensure all watchkeepers are confident in the actions to be taken in the event of dragging or losing an anchor and there is a contingency plan ready for implementation in the event of having to proceed to sea or re-anchor. Also, watchkeepers and senior officers must be aware of the reporting requirements to the coastal state in the event of losing an anchor so that mitigation measures can be put in place if required.
  • As the restrictions on the cruise industry ease, it must be remembered that this period of prolonged anchoring may have decreased the life span of the anchoring equipment. A full assessment of the future suitability of the anchoring equipment should be undertaken at the earliest opportunity or the next dry-docking period.

IACS advises that the anchoring equipment is not designed to hold a ship of fully exposed coasts in rough weather or to stop a ship that is moving or drifting.

In these conditions the loads on the anchoring equipment increase to such a degree that its components may be damaged or fail due to the high energy forces generated, particularly with ships with high windage.

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Source: MAIB

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