Lifting Ehime Maru The civilian salvage vessel Rockwater 2 is back in Honolulu Harbor again preparing for the final rigging operation later this week when the Navy will begin the unprecedented task of trying to raise the 830-ton Ehime Maru.
proves costly, tough
A salvage ship returns later this
week to the wreck site off OahuBy Gregg K. Kakesako
gkakesako@starbulletin.comRockwater 2 returned to the harbor yesterday to re-rig the forward end of the top lifting frame from a single-cable to a double-cable lift configuration. That lifting and spreader assembly, which will be suspended above the Ehime Maru, will distribute the vessel's weight when it is lifted and transported to a shallow-water recovery site about one mile south of Honolulu Airport's reef runway.
The Rockwater 2, a 5,991-ton Dutch-made salvage vessel, is expected to be at Pier 1 for two to three days before returning to the deep-water recovery site as early as Wednesday.
The 190-foot Ehime Maru now rests in 2,000 feet of water nine miles south of Diamond Head where it sank after being hit by the nuclear attack submarine USS Greeneville on Feb. 9.
The Navy is attempting to raise the vessel and move it to shallower waters where divers can search for nine people -- four high school students, two teachers and three crewmen -- whose bodies were never recovered.
Recovery operations and several setbacks have cost the Navy $60 million so far. The Navy has never raised a vessel as heavy as the Ehime Maru from a depth of 2,000 feet -- well beyond the capacity of divers. So far, all operations have been done by remote-controlled vehicles.
Last week, the crew of the Rockwater 2 attached a metal lifting plate to the bottom half of the spreader assembly. This bottom frame remains suspended above the Ehime Maru.
When the Rockwater 2 returns to the site this week, it will connect the top and bottom frames and then lift and transport the Ehime Maru 12.5 miles to the shallow-water site. Two powerful linear winches, each capable of lifting 500 tons, will be employed. These winches will deploy steel cable 5 inches in diameter. Four of these cables, with a total breaking strain of 3,200 tons, will be used to raise the Ehime Maru.
The Ehime Maru will be raised 90 feet above the ocean bottom for the voyage to the shallow-water site. The Navy estimates that the lifting sequence will take about 10 hours.
The Navy said the trip may take several days because the Rockwater 2 with the Ehime Maru suspended below will be traveling about 1 knot (1 nautical mile per hour, or 1.16 mph). Additionally, the move only will be done during the day so the Navy can watch to see if any of the 10,000 gallons of diesel fuel and lube oil still trapped in the ship seeps out.
The USNS Sumner, a 328-foot oceanographic survey vessel, will lead the Rockwater 2 to the reef runway site, measuring currents and relaying safety information.
Capt. William Aldinger, Pacific Fleet oceanographer, has said he does not believe the Rockwater 2 will face any major underwater obstacles until, with the Ehime Maru in tow, it reaches a reef shelf, about a mile before the shallow-water recovery site.
There the Ehime Maru will have to be raised more than 1,500 feet up a steep wall in a short period.
The Navy plans to let the Ehime Maru rest at the shallow-water site in about 115 feet of water for about two days before beginning diving operations. Japanese civilian and Navy divers may spend up to a month searching for remains and personal effects. The Navy believes that only five to seven of the nine missing people may be entombed in the vessel.
Once that project is completed, the Ehime Maru will be taken by a barge to a deep-water site 12 miles off Barbers Point and sunk in 6,000 feet of water.