In case of weather deteriorating whilst in the anchorage, delaying the decision to depart from the anchorage for too long may result in a difficulty in recovering the anchor. Weighing the dragging anchor may require additional time. Furthermore, in heavy wave/swell, the risk of anchor loss at the time of heaving up from the bottom increases significantly – this is because the ship’s vertical motion may result in rapid overloading of the anchor chain.
Dragging anchor might be manageable if the amount of space available to the ship allows for it. However, the ship is likely to be in proximity of other ships or navigational hazards and the tolerance for uncontrolled movement may be very low. As the speed of dragging anchor in strong wind may quickly reach about 4 knots, the amount of time available to regain control of the situation is typically very limited.
Dragging anchor is more likely to occur when the ship is light (in ballast condition) and has increased windage. Therefore, increasing the ship’s draught and/or reducing the trim by the stern are effective precautions against dragging anchor. It may also be necessary to restrict other activities which increase windage, such as opening hatch covers or extending gantry cranes.
There have been cases where opening large hatch covers in strong wind became the ultimate trigger for dragging the anchor.
PREPARING FOR THE
ANCHORING OPERATION The planning and assessment process of the anchoring operation will have a direct bearing on the likelihood of dragging anchor.
Like any critical operation, anchoring should be planned and subject to a robust risk assessment. Where applicable, these considerations should be an integral part of the passage planning process. It is strongly recommended that the Safety Management System (SMS) provides the necessary support in this regard.
The essential information which should be obtained and considered includes, but is not limited to:
• Assessment of the seabed as the holding ground • Evaluation of depth and the topography of the bottom • Proximity of hazards • Amount of space available to the ship whilst anchoring; traffic conditions and any congestion
• Weather and tide conditions prevailing at the time of anchoring, as well as the forecast and tidal prediction for the duration of stay
• Any shelter provided by land in the vicinity • Navigational marks or landmarks which could be used for terrestrial position fixing with sufficient accuracy for early detection of any movement
• Availability of navigational information – charts, sailing directions, local information.
The above information should be thoroughly assessed. It is recommended that a structured assessment process is in place and that the involved personnel are suitably trained. This process should then be subject to a periodical review, for example through the established navigational audit or navigational assessment programme.
If the ship’s typical operational activities involve any special requirements, or if they are subject to change, they should be reflected in the assessment process and any additional technical, procedural or training should be addressed.
In result of the above assessment, the anchoring plan should be established for the operation. This should include any required tests and checks, the anchoring and the organisation of the bridge team and anchor party (i.e. personnel attending to the anchoring operation on forward deck), the planning of the subsequent anchor watch and the level of readiness/manning.
Prior to anchoring, the anchor party, in particular the team leader, should have adequate understanding of the plan as it may have direct bearing on the execution of the operation and personnel safety.
Shipboard operational instructions, as well as the SMS procedures should take the operational limits of the equipment into account. Additional familiarisation or training may need to be provided for ship officers. To maintain awareness, it is also highly recommended to display a bridge poster, such as the one collated by INTERTANKO.
THE REPORT | MAR 2024 | ISSUE 107 | 87
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