By BRUCE SMITH, Associated Press WriterMon Sep 25, 7:38 PM ET
The U.S. Navy has approved plans to conserve the hand-cranked Confederate submarine H.L. Hunley by soaking the sub in high pH water to remove corrosive salts from the iron vessel.
State Sen. Glenn McConnell, who chairs the South Carolina Hunley Commission, said Monday he expects the Hunley could be conserved by 2013 with the sub going into the pH bath in about two years.
The Hunley sank the Union blockade ship Housatonic in 1864, becoming the first sub in history to sink an enemy warship. But it never returned with its crew of eight.
The wreck was located 11 years ago off Charleston, raised in 2000 and has since been in a conservation lab in North Charleston.
The current plans call for soaking the submarine in high pH solutions such as sodium hydroxide or sodium bicarbonate to remove salts from the iron.
Innovative research using subcritical fluids could shorten the conservation time, but "this new process is not far enough along at this time to benefit the conservation," retired Rear Adm. P.E. Tobin, director of Naval History for the Navy, wrote McConnell earlier this month.
The Navy had to approve the conservation plan because, under an agreement signed a decade ago, the federal government retains title to the sub while South Carolina has permanent custody.
Clemson researchers have been experimenting to see if the subcritical method holds promise for project. In such technology, fluids take on the characteristics of both a gas and a liquid under intense heat and pressure and have unique dissolving characteristics.
"We're going to continue the research because the way the conservation plan has been outlined, it is not incompatible with using subcritical at some point," said Michael Drews, the materials scientist heading the Clemson University research team helping with the conservation.
Electrolysis, another more traditional method used on large marine artifacts in which a slight electric current is passed through the water to remove the salts, has been ruled out.
Drews said that in some applications the current doesn't always penetrate places where metals are joined. One objective of the conservation plan is that the sub be conserved without having to take it apart.
"There have been cases on complex artifacts where it (electrolysis) has not worked particularly well," Drews said.
Tobin's letter said that exhibition requirements should not shorten the timeline for completion of conservation, but the submarine's response to the extraction of chlorides and stabilization must be the deciding factor.
Drews said only scientific monitoring will determine when the process is done.
"We have only one chance and that is to do it right," McConnell added.
Navy approves Hunley conservation plan - Yahoo! News