Extra precautions might have prevented an anchor-dragging incident in Weymouth Bay involving a product tanker, say the UK’s MAIB in a preliminary report just released. More cable on the port anchor, and preparations for dropping the starboard anchor might have avoided the Lilesand-registered product tanker Mariella that could have led to collisions with other ships at the anchorage and grounding last January.
Says the MAIB report.
On the evening of 9 January 2008, the product tanker Mariella was brought up to 8 shackles on the port anchor in the Bad Weather Refuge Anchorage in Weymouth Bay. The ship had been arranged to berth in Portland harbour to make permanent repairs to a fracture in the hull and to replace the main engine turbo charger, which had failed the day before. The turbo charger had been locked, which caused the ship’s speed to be reduced to dead slow ahead, giving a maximum speed of about 4.5 knots. The wind overnight at the anchorage was south-west force 6/7. However, the forecast for 10 January was south-west force 7 to severe gale 9, occasionally storm force 10, and decreasing force 4 at times.
At 0936, the ship began to drag her anchor to the north and toward the shoreline. The officer of the watch notified the master and the engine room. At 0951, the engine was started and the anchor party began weighing anchor. Following a temporary suspension of operations due to a hydraulic line failure, the anchor was aweigh at 1039. With limited engine power available, the master was unable to manoeuvre his ship to the south and she was set towards other ships in the anchorage and towards the lee shore. At 1111, the port anchor was let go to 9 shackles, which arrested the ship’s drift at about 2 cables from the 10 metre contour line.
The master requested the assistance of a harbour tug, which was used to hold the ship’s head into wind while he attempted to let go his starboard anchor. The coastguard mobilised the salvage tug Anglian Earl, which was alongside in Portland harbour. At 1254, Anglian Earl made fast her tow line fast to the ship; the two anchors were weighed and the tug and tow proceeded into Portland harbour. Mariella was made fast to the Deep Water Berth at 1700.
The Deputy Chief Inspector has written to Thome Ship Management Pte Ltd advising that, in the circumstances, the master could have taken extra precautions to prevent the ship dragging anchor such as deploying more cable on the port anchor and preparing the starboard anchor for letting go or lowering it onto the sea bed to prevent excessive yawing.