Rudder cracks in Alaska tankers

BP’s two new double-hulled Alaska Class oil tankers are out of service following discovery of cracks in the rudders of both vessels. A spokesman for Alaska Tanker Co., which operates the ships, says that the cause of the cracks remains a mystery. The first of the Alaska Class, the Alaskan Frontier, was delivered by NASSCO in August last year and is expected to be out of service for several weeks pending repairs to cracks in both its rudders.

Divers discovered the rudder cracks during a scheduled inspection of the Alaskan Frontier last Saturday and reports state that the largest measures just under 3 metres long.

A subsequent check of the newer sister ship, the Alaskan Explorer, found three cracks on one of its rudders, the longest measuring 0.40 metres.

NASSCO is currently building the final two Alaska Class tankers, due for service by the middle of next year, and BP has options for two more. The ships’ design places strong emphasis on environmental safety and redundancy. In addition to a double-hull, the ships have twin diesel-electric propulsion systems in segregated engine rooms, two propellers and twin rudders. They are built to ABS class.

The ships? operator says that this was not a catastrophic failure and that the problem has been caught very early. According to an industry source, the Alaskan Explorer is expected to return to service by the end of this week. As a precaution, a tug will escort the unladen ship when it enters Prince William Sound. Repairs to the Alaskan Frontier will take longer and the ship will likely will be out of service until July. Both tankers are docked at a shipyard in Port Angeles, Washington.

The company has put together a team of shipbuilders, engineers and inspectors to try to determine what caused the cracks.