Posted on: Friday, September 27, 2002

Tests hint Arizona's hull still sturdy after 63 years

By William Cole
Advertiser Military Writer

The Arizona Memorial sits above the sunken remains of the ship where 1,177 sailors died in Pearl Harbor in 1941. Advertiser Library Photo

Divers who took metal samples for the first time from the hull of the USS Arizona last month came up with some qualified good news: the historic battleship is not decaying as rapidly as thought.

"What we can say at this point — and this is like dripping-wet, standing-on-the-dock early — it looks like the rate of corrosion is well below that of what would be expected for steel in seawater," Larry Murphy, an archaeologist with the National Park Service's Submerged Cultural Resources Unit, said yesterday.

The Navy and park service had been worried about deterioration of the battleship that was hit by Japanese forces off Ford Island on Dec. 7, 1941, the day of infamy that ushered the United States into war.

The 608-foot battleship that took 1,177 sailors to their graves still leaks oil, and officials estimate that more than 500,000 gallons remain within its damaged confines.

"People will say, gee, is it going to collapse and let the oil out?" Murphy said. "That's what everyone wants to know."

But Murphy added, "All of the tests that we have done to date have indicated that (collapse) is not imminent."

During the last two weeks in August, divers from the National Park Service and the Navy's Mobile Diving and Salvage Unit 1 drilled holes and took four core samples from each side of the hull, where the original thickness was 1/2 inch to 7/8 inch.

Murphy said the samples will have to be subjected to laboratory analysis to determine the implications for structural integrity. The first battery of tests looking at composition, ductility and strength probably will be done within a year, he said.

"We know that the vessel is encrusted (with silt and marine life) — it has a concretion on it that reduces the rate" of corrosion, Murphy said. "We did not know how much, and that is what we're establishing — what the corrosion rate has been since the sinking of the vessel."

Murphy said early indications of hull metal thickness show the rate of deterioration is lower than expected. But that says nothing about the strength of the steel, he notes.

"The thing that should be kept in mind is no one has really tried to do this kind of in-depth analysis and projection," he said.

Murphy could not say what the results mean in terms of a long-term outlook for the stability of the national monument.

The National Park Service also is studying the oil being released from the Arizona and its deterioration rate. By testing, researchers can determine if released oil was subjected to seawater for a long time, or if it's coming from new ruptures in the battleship's oil tanks.

Murphy said it looks like most of the released oil has had long-term exposure to seawater and is more or less in a deteriorated state — which is, again, qualified good news that further tests may confirm.

Murphy said that the last time divers conducted research dives on the Arizona was in December. The park service in 1983 began a documentation process of the sunken battleship. Tests to gauge metal thickness without taking samples were conducted in the late 1980s.

One of the scientific partners in the latest round of tests will be the National Institute of Standards and Technology, which Murphy said is involved with examination of steel from the World Trade Center.

Core sampling was not done previously because every effort is made to be as non-intrusive as possible with the landmark, Murphy said.