DEEP WATER ANCHORAGES: CHALLENGES & DIFFICULTIES IN WEIGHING ANCHOR

Let's take this opportunity to discuss the challenges and difficulties in weighing anchor in deep waters. Due to various practical compulsions, large vessels are required to anchor in deep waters.

- CAPT KIRAN KRISHNAJI JOSHI

This article aims to study the difficulties during weighing an anchor on some occasions on different ships. The topic must be carefully addressed keeping in mind the safety of the crew involved as well as the process of heaving up an anchor.

CAPABILITY OF ANCHOR HANDLING EQUIPMENT:

On a VLCC, the designed pull of windlass is about 72 tons. The weight of each length of a shackle (27.5 m) is about 9 tons & the weight of an anchor ranges from 18 tons to 24.5 tons.

Subsequently, when the anchor is off the bottom, the total weight of the anchor and cable in a depth of 135 m is almost close to 72 tons (considering the anchor weight as 24.5 T). When a VLCC is in ballast condition, the actual height through which the anchor needs to be heaved up further increases due to forward freeboard being about 12 m more than that during the laden condition. Thus in ballast condition, the cable is about five and half shackles on deck by the time anchor is off the bottom. This poses a great challenge to weigh the anchor. Furthermore, during summer months and in deep waters, one may face more difficulties in heaving up an anchor on a ship depending on the age of ships and condition of equipment.

CAUSES OF DIFFICULTIES WHILE HEAVING UP AN ANCHOR:

While heaving up an anchor, there can be multiple reasons behind the difficulties which can be as follows:

• Aging of the hydraulic motors of the windlass which are not easy to inspect except during layup repairs/dry docking.

• Degradation of quality of oil in the hydraulic system or improper grade of oil being added/used than recommended grade.

• Higher ambient temperature resulting in a higher temperature of system oil lowering the viscosity of oil thus causing reduction in pulling power.