DNV GL and Partners Address Anchoring Safety
DNV GL, Gard and The Swedish Club have been investigating a rising number of anchor losses reported over the last several years.
Namely, the root cause of many groundings and collisions, lost anchors are among the top five reasons for claims costs.
Based on an analysis of damage cases involving anchor and anchor chain losses, the project partners have issued a presentation identifying the most frequent technical and operational causes, and some steps crews and operators can take to address them.
“One of the key takeaways of our investigation is the importance of the officers and crew being aware of the environmental loads their equipment is designed for,” says Håkon Skaret, senior principal engineer at DNV GL. “If these limits are not taken account of in shipboard anchoring procedures, there can be significant damage to the vessel – even beyond the loss of anchor and chain. Many anchor losses are avoidable, if the proper maintenance and handling procedures are adhered to.”
Examining the losses in terms of technical or operational failures revealed some key issues. On the technical side, the D-shackle is the technical component with the highest loss causing failure rate. As such it should be inspected whenever possible, with special attention paid to the taper pin. Securing the anchor tightly in the hawse pipe during voyage can help to avoid excessive vibrations which can cause the pin to come loose. The windlass brake is essential to control the pay-out of the chain, and many anchor losses are reported due to loss of brake power and uncontrolled release of the chain. Corrosion of the drum and wear of the brake band lining reduces brake capacity and it is therefore essential that the tension of the brakes is adjusted and liners replaced in accordance with the manufacturer’s instructions.
“Operationally, every anchoring operation is unique,” says Skaret. “In practice, the crew and officers need to be aware of the risks and assess them thoroughly, especially in heavy weather. In almost half of the cases we saw that environmental risk factors, such as the weather, strength of the currents and water depth, played a significant role in the loss. To help shipboard personnel in this respect, shipping companies can make sure that procedures for safe anchoring operations are implemented in their safety management systems.”
Anchor and chain loss can often lead to collisions and grounding, which can result in additional damage to a vessel. Adding to the costs of anchor loss is the increasingly common requirement from port authorities that lost anchors are recovered.