Risks of dropping the anchor underway

Mars Reports 2013

The Nautical Institute has issued Mars Report No.40 regarding risks of dropping the anchor underway. The official report has been edited from The Dutch Safety Board

In calm weather and good visibility, a cargo vessel under pilotage while departing port was overtaking a tug towing a pontoon. The cargo vessel’s electrical needs at the time were being supplied via the shaft generator. Both of the ship’s service generators were shut down to save on fuel.

While overtaking the pontoon, the cargo vessel’s main engine suddenly failed. Since the electrical systems on board the vessel were linked to the main engine via the shaft generator, the electricity failed as well and for a short period of time the vessel suffered a blackout. During the blackout, the rudder unexpectedly turned to port, causing the vessel to deviate sharply from its course and toward the tug and tow. In order to prevent a collision, the captain, on VHF radio, ordered the anchor let go. As there were crew on deck at the time, the anchor was let go very quickly after the order – within 15 seconds. At the time the anchor was let go the cargo vessel still had a speed over ground (SOG) of 7.5 knots.

Despite the attempts by the AB to secure the winch brake, the anchor chain continued to run out. The last length of chain had broken loose from the chain locker, and the AB was hit and fatally injured by the bitter end.

The cargo vessel collided with the pontoon almost simultaneously with the breaking free of the anchor chain. Both vessels sustained limited damage as a result of the collision.

Lessons learned The use of the anchor to slow down the ship in an emergency: IACS stipulates that an anchor must be constructed in such a way that it is suitable to anchor a ship temporarily in ‘moderate’ ambient conditions. The anchor gear is not designed to stop a ship. Anchoring at high speed is an extremely risky operation that may result in fatal injuries to crew members and serious damage to the ship. Such a manoeuvre should only be considered in an extreme emergency. The captain, in consultation with the bridge team, should assess whether the potential benefits of such a manoeuvre outweighs the substantial risks for the crew and ship.

View more information at Mars Report No.40/2013

Source: The Nautical Institute