200840 Damage to underwater cables

Arriving about a week early for her loading, a general cargo ship that had almost arrived at the pilot station, was instructed to wait off-limits. After hastily consulting the charts and publications, and being aware of hi-jacking and piracy threats in the region, the Master selected an offshore anchorage just outside the 12 mile line, but within visual range of the signal station.

After turning the ship around in heavy traffic and steaming back about 15 miles, the Master anchored in the chosen spot in depths of about 25 m, paying out five shackles. During the final approach to the anchorage, he noted charted submarine cables in the vicinity and, perhaps due to the subconscious feeling that he was anchoring in 'high seas', coupled with a momentary lapse of concentration, he mistakenly interpreted each one-cable division on the large scale chart's latitude scale as one mile. As a result, the Master was under the impression that he was four miles clear of the nearest submarine cable, but, in fact, had anchored 0.4 miles from it.

After about four days the ship, which was always wind-rode, slowly dragged anchor, snagged and damaged the submarine communication cable. Unfortunately, none of the bridge team realised the slow dragging of the anchor, having monitored the ship's position by distant radar ranges, which failed to change appreciably.

Root cause/contributory factors
Hasty, forced decision to select an anchorage offshore;
Wrong interpretation of distance scale;
Poor bridge team management, error chain not identified;
Inadequate clearance from submarine cable;
Inadequate scope of cable under prevailing conditions;
Ineffective anchor watch.

Lessons learnt
Harbour movement instructions for an inbound vessel must be communicated well in advance of her arrival.
The bridge team organisation must ensure that every action of one member is monitored and approved by another so that an error chain is not allowed to develop.
If there is sufficient room, a longer scope of cable must be paid out than the normal length of four to five times the depth.

As a further guide to mariners, here is a recent advisory from the West of England P&I Club:
07/03/2008 Underwater Cables and Pipelines

Damage to underwater cables and pipelines by ships' anchors continue to produce very large civil liability claims against shipowners, not only for repairs but also for the resulting interruption of production or supply of power, communications or products such as oil or gas.

It now appears that coastal state authorities may be taking a tougher line in respect of vessels damaging underwater facilities.

In certain jurisdictions, and as occurred recently in the Gulf, where a vessel is reported to have damaged a communications cable some distance away after dragging anchor in heavy winds, criminal proceedings may be brought against vessels' masters and they and/or crews may be arrested.

When anchoring, Masters should ensure that the anchor is dropped well away from any underwater cables or pipelines, taking into account the local weather forecast and the likely track of the anchor if it starts to drag. Masters should also be mindful that ships may move a considerable distance very quickly in such circumstances unless the main engine is ready for immediate use.