PEARL HARBOR — Its displacement is more than twice that of a Los Angeles-class submarine, and eight times that of the Bowfin submarine next to the USS Arizona Memorial visitors center.

The USS Ohio is big and long at 560 feet, and for two decades patrolled the seas with Trident intercontinental ballistic missiles tucked into 24 vertical launch tubes.

Yesterday, the Ohio pulled into Pearl Harbor to flex its muscles in a whole new way.

From 2003 to 2006 the sub underwent a $1 billion refueling and refit to become a stealthy platform from which to conduct surveillance, deliver SEAL commandos and launch Tomahawk cruise missiles. All nuclear missiles were removed.

Four subs in the Navy's fleet of 18 ballistic missile subs, or "boomers," are being similarly converted.

For the next several weeks, the Ohio, which left Washington state on Oct. 14, will embark 66 Pearl Harbor SEALs and sailors from SEAL Delivery Vehicle Team 1 and other commands for final training before heading out into the western Pacific on the first real mission for the converted subs.

"We're going to be getting real-world targeting that we really have to be able to act on on very short notice, and we're going into places where we must remain undetected for weeks, if not months, at a time," said Capt. Chris Ratliff, the commander of the Ohio.

That mission will take the Ohio into the global war on terrorism, Ratliff said.

Under the requirements of the Strategic Arms Reduction Treaty, or START II, agreed to in 1992, the number of strategic U.S. missile submarines was limited to 14 from the year 2002, according to www.naval -technology.com.

Rather than decommission four submarines, the Navy is converting them to guided missile subs.

The boomers are big to begin with, and have 24 of the 8-foot-wide by 42-foot-deep missile tubes to work with.

Ratliff said he'll be deploying with 15 of those tubes loaded with seven Tomahawk cruise missiles each.

Yesterday, the heavy, wide circular hatch on one tube was opened, revealing the Tomahawks arrayed in a circular pattern inside.

Two tubes are used as lock-out chambers for divers, and other tubes are being used for gear storage and for experimental deliveries.

One of the big advantages of the converted ballistic subs is the ability to conduct not only SEAL missions, but SEAL campaigns, conducted from an undetected position in nearshore waters referred to as the littorals.

"With the capabilities of the submarine, we're going to be right there, the whole time, continuously supporting the SEALs. Ready to receive them back on board the boat and turn them around again just as soon as they are able," Ratliff said.

For the crew of the Ohio, it's a mission that puts them closer to the tip of the spear.

"It's always going to be a real-world mission every time you go out," said Master Chief Steven Schultze, 38, of Placerville, Calif., the senior enlisted sailor in the engineering department.

Ratliff led a media tour of the Ohio yesterday past the reddish former ballistic missile tubes that protrude like redwoods through the sub's four decks.

The sub carries a crew of 15 officers and 140 enlisted men, but can also bring on board more than 100 special operations forces.

The Ohio carries 66 extra beds or "racks," for 215 total. The bed space provides only a few feet of height, but curtains provide a little bit of privacy.

Submarines typically do what's called hot-racking, which means three sailors assigned to two beds that are used in shifts, Ratliff said.

"To have 66 extra beds gives the boat so much more mission flexibility," Ratliff said.

When SEALs come back from a mission, the sub is big enough that it can provide the facilities for the commandos to get rested, get fed and get back into shape for another mission.

In high seas, the Ohio has the capability to be at periscope depth and be stopped virtually dead in the water for SEAL missions or Tomahawk launches, Ratliff said.

It also has sophisticated sonar and sensing technology to bring it safely into nearshore waters and can navigate through a minefield.

Pearl Harbor will be receiving three of the first four new Virginia-class submarines being built, which have the capability to bring commandos to a mission — but not as many as the converted ballistic missile subs, and not as long as the Ohio can support them.

The Virginia-class sub USS Texas will arrive in 2009 followed by the USS Hawaii later that year.

"That's a unique capability (of the Ohio). No other submarine can do that," Ratliff said. "No other nation in the world has that capability, for the extended (special operations forces) campaign."

A 30-by-50-foot space that used to be jammed with navigation equipment for Trident missiles has been cleared out and condensed with current uses, and the space now is a 16-station battle management center with plasma-screen TVs that can be overseen by a general or admiral.

The Ohio, which has what are called "blue" and "gold" crews that swap out on the sub, was in Hawai'i waters training with SEAL Delivery Vehicle Team 1 from November 2006 to May of this year before heading back to the West Coast.

The Hawai'i-based SEALs use swimmer delivery vehicles, which are like a convertible for scuba drivers and are launched from a dry-deck shelter on the back of a sub, and the Advanced SEAL Delivery System, a mini-sub that has proved difficult to develop.

BUSH HONORS FALLEN HAWAI'I-BASED SEAL

Six of the Hawai'i-based SEALs deployed to Afghanistan and five were killed in a firefight in the mountains in June 2005 and failed rescue attempt when a Chinook helicopter was hit by a rocket-propelled grenade.

One of those SEALs, Lt. Michael Murphy, was awarded the Medal of Honor posthumously yesterday by President Bush.

Ratliff said crews of the Ohio will swap out in Guam in three months, again four months later, and then four months after that, his counterpart will skipper the sub back to Bangor, Wash.

Ratliff said taxpayers get 20 more years of use out of Ohio, and a stealth capability that can't be duplicated by helicopters or ships delivering commandos.

Philip Coyle, a defense analyst with the Center for Defense Information, said by showcasing the Ohio, the Navy is trying to demonstrate its relevance in the fight against terrorism "and its ability to adapt to the new world order."

Reach William Cole at wcole@honoluluadvertiser.com.