US to search sunken Japanese trawler

The Rockwater 2 will try to lift the trawler

The United States Navy is to begin operations this week to search the wreckage of a Japanese fishing vessel that was accidentally sunk by one of its submarines in February.

A civilian support ship, the Rockwater 2, is expected to try to lift the Ehime Maru from the sea bottom off the Hawaiian island of Oahu and drag it to shallower waters, where divers can work on the wreckage.

It is hoped that the bodies of nine Japanese students and teachers believed to be trapped in the sunken vessel can then be recovered.

The officer in charge of the operation said that raising the ship had as much as an 80% chance of success, but that the dragging process could cause more problems.

Click here for diagram of operation

"I have very high confidence that we will be able to get to the point where we can lift the ship," Rear Admiral William Klemm said. "I think the much greater risk comes at the point where we raise the ship and have to move it."

The 190-foot (38-metre) Ehime Maru, used to instruct Japanese students about the fisheries industry, sank when the USS Greeneville surfaced beneath it during an emergency drill on 9 February.

It is said to be the largest vessel ever attempted to be raised in such an operation.

The Ehime Maru was used for training

The Rockwater 2 will head out to the site of the accident for the operation, which will be carried out in four stages:

• The trawler will be raised from the ocean floor 2,000 feet (610m) below the surface. The Rockwater has special thrusters to keep it stationary as remote submersibles attach four-inch cables to the trawler

  Rockwater 2

  Length: 323 feet

  Breadth: 59 feet

  Weight: 5,991 tonnes

• It will be then carried in a giant sling about 100 feet above the ocean floor for 13 nautical miles and set down in shallow waters about 115 feet deep

• More than 45 divers will work from a barge anchored over the ship to recover the bodies and remove diesel fuel and other substances potentially damaging to the marine environment

• The trawler will then be sealed and transported using a heavy construction barge to a final re-location site in deep ocean.

Difficulties

If everything goes smoothly, the lifting operation is expected to be completed by the end of August. Divers will enter in September and the operation is due to be completed in October.

Ehime Maru

Length: 180 feet

Breadth: 32 feet

Tonnage: 741

Speed: 12.5 knots

Constructed 1996

But Rear Admiral Klemm said if an initial inspection revealed severe structural damage, the operation might have to be halted.

He also said that he only expected between five and seven of the nine bodies to be recovered because of difficulties gaining access to compartments of the trawler.

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