Swedish Club’s casebook describes a total loss incident, where an anchored vessel ran aground due to typhoon.
A laden 45,000 MT deadweight tanker had anchored in a bay outside an Asian port. It was late summer and the vessel was waiting for a berth to discharge its cargo.
Weather warnings forecast
Weather warnings about an approaching typhoon for the area where the tanker was anchored had been broadcast for two days prior to the vessel arriving at the anchorage. The tanker had anchored with 7 shackles of chain in the water.
There were some islands around the anchorage and the Master considered the anchorage would be a suitable place to ride out the approaching typhoon, which had been upgraded to a category 2 typhoon.
Around 04:00 the following morning the wind increased to Beaufort scale 9 and the Master told the Chief Officer to pay out 2 more shackles of chain in the water, making a total of 9.
During the morning the wind continued to increase to Beaufort scale 12 which caused the anchor to drag.
Wind continued to increase
The Master tried to manouvre the vessel into the wind using the engines. However, two hours later the wind had increased even further, and it was not possible to turn the bow into the wind with the vessel at anchor. The vessel was now turned so that the wind was acting on the broadside of the dragging vessel.
The Master ordered the Chief Officer to heave up the anchor. However, this was not possible as the vessel was dragging. The windlass was not designed for these environmental loads, as it was only designed to lift the weight of the anchor and three shackles of chain (82.5m) in calm water.
Vessel ran aground
At this point there was nothing the crew could do, and the vessel ran aground on one of the islands surrounding the anchorage.
The Master sent a distress signal and the crew abandoned the vessel. Shortly after abandoning the vessel the crew was rescued by a local tug. Fortunately, there was no pollution and no injuries to the crew.
- It is not uncommon for crews to be unaware of the environmental loads for which anchoring equipment is designed. Classification societies have unified rules for the design of anchoring equipment, and it is essential that the crew is aware of these limits.
- A category 2 typhoon, as in this case, will have a predicted wind velocity of about 45 metres per second (about 87 knots) which is almost twice the load the anchoring equipment is designed for.
- If heavy weather is anticipated, as in this case, it is important that the vessel leaves the port/anchorage as soon as possible. This case highlights the risks and consequences of not leaving in sufficient time.
- It is recommended to use weather routeing which will warn about approaching heavy weather and suggest an alternative route for the vessel.