A growing number of cases of lost anchors, anchor drag and anchor withdrawals prompted DNV, Gard and The Swedish Club to collaborate on an anchor loss awareness campaign in 2016. Despite the taking of awareness then on the most frequent technical and operational problems, we are even today an increase in cases. Could there be new reasons for the increase in anchor loss and drag incidents?

Due to congestion, vessels spend more time at anchor and anchor in areas more exposed to extreme and sudden environmental conditions. This is likely due to the state of our global economy with the past few years of economic downturn and the COVID pandemic with the ensuing logistical disruptions for crew changes and cargo handling.

Due to the pandemic, we have also seen passenger ships temporarily stranded in exposed anchorages. Container ships and car carriers that did not often use their anchoring equipment must now use it for long periods of time while waiting in queues outside loading terminals. Climate change is also contributing to losses with more frequent extreme weather events and in places previously known to be benign and safe. Climate change has also resulted in longer periods of high and rapid water in the approaches to rivers, for example the Mississippi.

Learning from the sinister data of the Gard

The Gard claims data from 2015 to 2020 confirm an upward trend in anchor loss and removal cases. We also studied vessel movements which show that a vessel with an anchor claim anchored on average 28% more often and spent on average 27% more time at anchor than a vessel without a claim to anchor. ‘anchor.

Likewise, vessel movement data revealed that in the same period 2015-2020, a vessel with an anchor claim spent on average 18% more weather in bad weather over the course of a year. than a ship without an anchor claim. Bad weather is defined as wind forces between the Beaufort scale 8 – 12, where 8 is gale forces and 12 is hurricane forces.

Risks and limitations of ship anchoring equipment

In most anchor claim cases, environmental risk factors, such as weather conditions, current strength, water depth, and holding ground, played a significant role in the loss. Typically, anchoring equipment is designed for temporary mooring in harbors or sheltered waters, but in today’s real world, many anchor locations are found outside sheltered waters.

We suspect that one of the key issues is a general lack of awareness of the environmental loads for which anchoring equipment is designed. Anchoring equipment is not designed to keep a vessel off fully exposed coasts in inclement weather or during frequent anchoring operations on the high seas. Under such conditions, loads on the equipment of Anchoring will increase to such a degree that its components can be damaged or lost due to the high energy forces generated.

Through the International Association of Classification Societies (IACS), classification societies have agreed on a unified set of requirements for anchoring equipment (UR A1) and refer to them in their class rules. .

Anchor Equipment Number (EN) calculations, as found in UR A1, are based on the following assumed environmental load conditions:

• Current speed: max. 2.5 m / s
• Wind speed: max. 25 m / s
• No waves (sheltered waters)
• Paid chain length range 6-10
• Good ground of maintenance

For vessels with an equipment length greater than 135 m, another UR A1 environmental condition may be considered:

• Current speed: 1.54 m / s
• Wind speed: 11 m / s
• High wave height 2m

The IACS UR A1 has recently been revised and the revised requirements of UR A1, Rev 7, September 2020 (corrigendum published September 2021) will apply to vessels contracted for construction from January 1, 2022. up to date of this last revision take into account the projected area before and the projected lateral area of ​​the large funnels in the calculations of the number of equipment to take into account their contribution to the anchoring loads. This change may be necessary due to the addition of scrubbers on many vessels which increase the profile of the funnel and thus affect the way the wind applies force to the vessel.

Trailing anchor

The most serious and costly cases occur when a ship pulls its anchor in strong currents or bad weather, resulting in collisions with other ships anchored nearby, groundings and ship loss, pollution or damage. damage to cables and pipes on the seabed.

“Dragging anchor” means that the vessel is drifting without retaining power, even if it has been anchored. It is important to note that it may take some time for the crew to realize that the anchor is dragging and the vessel is drifting. Once completed, it will take time to weigh (raise) the anchor, start the engines and restore the vessel to full maneuverability, a period during which the vessel may run dangerously close to other vessels or structures, or in conditions. shoals.

Where are the anchors lost and should they be removed?

The heat map below shows the locations of anchor losses and anchor removal cases recorded by Gard over the past six years. The map confirms that the concentration of cases (large circle sizes) is found in areas with larger shipping ports and in areas most affected by strong currents and bad weather.

For example, the map shows that there are a significant number of cases in and around New Orleans and the wider Mississippi Delta. 2019 and 2020 were exceptional years for high river related casualties, due to the long period of high river conditions in the Mississippi River. When certain areas of the river are considered to have reached a high water level, local authorities require that all deep draft vessels that are not moored alongside or moored to a buoy have at least three means to maintain its position. This can be achieved by using the two anchors in addition to the propulsion system or by being assisted by a tug as a third means of maintaining in position. When using both anchors, there is a higher risk that the chains will cross each other, get tangled and damage the anchor.

The map also shows that there are a surprising number of anchor claims in and around Fujairah, UAE. This area is expected to have mild weather and sea conditions. However, the water depth at Fujairah Anchorage is considered deep water and ranges from 70 to 130 meters. “Letting go” of the anchor in such deep water could cause exhaustion of the braking system and leave the windlass unchecked, damaging the windlass, the bitter end or, in some cases, causing the complete loss of the cable and of the anchor.

One of the main conclusions of accident investigations is the importance for the crew to be aware of the environmental loads for which their anchoring equipment is designed. If these limitations are not taken into account during anchoring operations on board the ship, the ship can suffer significant damage, even beyond the loss of the anchor and chain.

Recommendations

Many anchor losses are preventable if proper maintenance and handling procedures are followed. Performing proper anchoring operations is vital to the safety of the vessel and, before anchoring, the master should consider the following:

Define a policy for conditions requiring leaving the anchorage – If a vessel is anchored in an area exposed to the elements, it is necessary to have a clear policy on when to leave. There have been instances where captains have come under commercial pressure not to leave an anchorage, and catastrophes have followed because the captain was tempted to “wait and see until the morning” when the weather forecast were bad.

Observe Mooring Equipment Limitations – Captains should be especially vigilant when mooring near shore in bad weather or in high rivers with strong currents and poor grip on the ground. When making the decision to stay or go, the captain should also be aware of the design limitations of the anchoring equipment. Some Masters may not be fully aware of these limitations; however, they are fixed by the class societies in their rules for calculating the dimensions, weights and strengths of anchoring equipment. With the mentioned limitations in mind, it can be seen from cases of ships pulling anchors in bad weather that sometimes captains placed too much faith in their ship’s anchoring equipment. Weather forecasts today are generally very reliable and captains should more often choose to weigh anchor and set out on time if weather is forecast.

Train and mentor the crew – Anchoring a ship safely can only be done with proper planning, a properly trained bridge team, and positive management and leadership on board. Owners and managers should ensure that this knowledge is transferred to subordinate officers through formal training and by making this knowledge available. Good seamanship is often learned on the job at sea. Appropriate anchor watches must be maintained, which includes the use of navigation equipment for the configuration of anchor watch alarms and parallel indexing. Additional precautions such as disbursing an additional cable and starting the motors immediately should also be considered.

Le Gard has previously, in collaboration with DNV and The Swedish Club, published a free awareness campaign to download and share, including a video identifying the most frequent technical and operational problems, and the actions teams and operators can take. to solve them. Our anchor awareness material remains highly relevant to preventing anchor loss and anchor dragging, so we recommend that members and customers review our loss prevention material and share it with their crew.

Disclaimer: It is important to stress that this publication should not be used as a comprehensive guide to the risks of anchoring and how to anchor a vessel and should not replace any requirements given by authorities or companies. classification.
Source: Gard, https://www.gard.no/web/updates/content/32664293/anchoring-awareness-revisited