Ship operators, Masters and crew need to be aware of the risks involved and assess the limitations of a vessel’s anchoring equipment.
In a recent DNV-sponsored webinar co-hosted by Gard and The Swedish Club, Senior Loss Prevention Executive Jarle Fosen shared Gard’s experience and recommendations.
Learning from claims data
Gard’s claims data from 2015-2020 confirm an increasing trend in anchor loss and removal cases, noting 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.
What is more, the vessel movement data also showed that during the same 2015-2020 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.
Risks and limitations
As Mr Fosen explains, in most anchor claim cases, environmental risk factors played a significant role in the loss.
“In general, anchoring equipment is designed for temporary mooring in harbours or sheltered waters, but in today’s real-world many anchoring locations are outside sheltered waters.”
Gard suspects that one of the key issues is a general lack of awareness of the environmental loads for which anchoring equipment is designed.
However, the International Association of Classification Societies (IACS) Class societies has agreed to a set of unified requirements for anchoring equipment (UR A1) and make reference to this in their Class Rules.
The anchoring Equipment Number (EN) calculations, as found in UR A1, are based on the following assumed environmental load conditions:
- Current velocity: max. 2.5m/s
- Wind velocity: max. 25m/s
- No waves (sheltered waters)
- Length of chain paid out scope 6-10
- Good holding ground
For ships with an equipment length greater than 135m, an alternative UR A1 environmental condition may be considered:
- Current velocity: 1.54m/s
- Wind velocity: 11m/s
- Significant wave height of 2m
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 1 January 2022.
The most serious cases take place when a ship drags its anchor in strong currents or bad weather, causing collisions with other anchored ships, groundings and loss of the ship, pollution or damage to cables and pipelines on the seabed.
Many anchor losses can be prevented if proper maintenance and handling procedures are followed. For this reason, the Master should take into consideration the following:
- Set a policy for the conditions requiring leaving the anchorage: If a ship is anchored in an area exposed to weather, it is necessary to have a clear policy as to when to leave.
- Respect the limitations of the anchoring equipment: Masters must be particularly vigilant when anchoring close to shore in bad weather or in high rivers with strong currents and poor holding ground.
- Train and mentor crew: Anchoring a vessel safely can only be carried out with proper planning, a properly instructed bridge team, and when positive on-board management and leadership are shown.
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