Anchoring awareness revisited

A recent DNV-sponsored webinar co-hosted by Gard and The Swedish Club looked at the risks involved when it came to the use of anchors. Senior Loss Prevention Executive Jarle Fosen has summarized the points made by Gard in the webinar.

Fosen observed that port authorities today were likely to require that lost anchors be found and removed, thereby resulting in a “wreck removal” case. He said that the more serious and very costly cases occurred when dragging anchors led to collisions, groundings, damage to subsea-cables and pipelines, or pollution.

Fosen said that a growing number of anchor losses, anchor dragging, and anchor removal cases prompted DNV, Gard and The Swedish Club to collaborate on an anchor loss awareness campaign back in 2016. However, despite the awareness raised then on the most frequent technical and operational issues, Fosen said that insurers were today still seeing an increase in the number of cases.

This led the insurers to consider whether there might be some new reasons for the increase in anchor loss and dragging incidents.

Because of congestion over the past year, ships were spending more time at anchorages and were anchoring in areas more exposed to extreme and sudden environmental conditions.

The pandemic had also resulted in many passenger vessels being laid-up temporarily but relatively long-term in exposed anchorages. Containerships and car carriers that did not often use their anchoring equipment were now having to use it for extended periods of time while waiting in the queues outside loading terminals. More frequent extreme weather events were occurring in locations previously known to be benign and safe. Climate change had also resulted in longer periods of high and fast water in river approaches, for example the Mississippi.

Gard’s claims data from 2015 to 2020 had confirmed an increasing trend in anchor loss and removal cases. The insurer also studied vessel movements, and these showed that a vessel with an anchor claim dropped the anchor on average 28% more often and spent on average 27% longer time at anchorage than a vessel without an anchor claim.

Similarly, the vessel movement data revealed that during the same 2015 to 2020 period, a vessel with an anchor claim spent on average 18% longer time in bad weather during a year than a vessel without an anchor claim. (Bad weather is defined as wind forces between Beaufort scale 8 and 12, where 8 equals gale force and 12 equals hurricane force.)

In most of the anchor claim cases, environmental risk factors, such as weather, strength of the currents, water depth and holding ground, played a significant role in the loss. Fosen noted that anchoring equipment was generally designed for temporary mooring in harbours or sheltered waters, “but in today’s real world many anchoring locations are outside sheltered waters”.

Fosen said that Gard suspected one of the key issues was a general lack of awareness of the environmental loads for which anchoring equipment was designed. It was not designed to hold a vessel off fully-exposed coasts in rough weather or during frequent anchoring operations in open sea. In such conditions the loads on the anchoring equipment would increase to such a degree that its components might be damaged or lost owing to the high energy forces generated.

Through the International Association of Classification Societies (IACS) Class societies have agreed to a set of unified requirements for anchoring equipment (UR A1) and make reference to this in their Class Rules.

The IACS UR A1 has been revised recently and the revised requirements in UR A1, Rev 7, September 2020 will apply to ships contracted for construction from January 1st 2022. The updates in that last revision include consideration for the front projected area and side projected area of large funnels in the equipment number calculations to account for their contribution to anchoring loads. Fosen noted that “this change may be required following the addition of scrubbers on many ships which increase the profile of the funnel and thereby affect how the wind applies force to the vessel”.

Dragging anchor

Fosen said that the most serious and most costly cases by far occurred when a ship dragged its anchor in strong currents or bad weather, leading to collisions with other nearby anchored ships, or groundings and loss of the ship, or damage to cables and pipelines on the seabed. With the concomitant pollution risks in all cases.

Fosen said that it was important to note that it could take some time for the crew to realize that an anchor was dragging and the ship was drifting. And, even when it has been realized, it would take time to weigh (lift) the anchor, start the engines and restore the ship to full manoeuvrable condition. During this period the ship might run dangerously close to other ships or structures, or into shoal water.

The concentration of lost anchor cases is found in the areas with larger shipping ports and in areas more affected by strong currents and bad weather.

There had recently been a significant number of cases in and around New Orleans and the wider Mississippi River delta. 2019 and 2020 were exceptional years for high river related casualties, due to the extended period of high river conditions in the Mississippi River.

Fosen noted that, when certain areas of the river were considered to have reached high water level, local authorities required all deep-draft vessels that were not moored alongside or moored to a buoy to have at minimum three means to hold its position. This may be achieved by using both anchors in addition to the propulsion system or being aided by a tug as the third means of holding position. However, when using both anchors there was a higher risk of the chains getting crossed, entangled, and damaging the anchor.

There had been a surprising number of anchor claims in and around Fujairah, UAE. This area is assumed to have benign weather and sea conditions. However, the water depth at Fujairah anchorage is considered deep waters and varies from 70 to 130 metres. ‘Letting Go’ the anchor in such deep water could cause the brake system to burn out and leave the windlass without control, damaging the windlass, bitter end, or in some cases resulting in total loss of the cable and anchor, Fosen said.

One of the key findings in casualty investigations was the importance of the crew being aware of the environmental loads for which their anchoring equipment was designed. “If these limits are not considered during shipboard anchoring operations, there can be significant damage to the ship – even beyond the loss of the anchor and the chain”, said Fosen.

Gard concluded that many anchor losses were preventable if proper maintenance and handling procedures were followed. The insurer said that performing correct anchoring operations was vital to the safety of the vessel.

https://www.gard.no/web/updates/content/32664293/anchoring-awareness-revisited