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A temporarily blinded periscope. A boat sitting idle on the surface that sonar cannot detect. Rough seas. Human error. All can be factors that help steer a state-of-the-art Navy submarine into a collision.

It has happened before.

Ken Hartung was a sailor aboard the fast-attack submarine USS Permit in 1965 when it rose to periscope depth just outside the Golden Gate Bridge and smashed a hole through a freighter drifting on the surface.

Hartung, who served on five Navy submarines and had been chief of the watch, is willing to bet that the same kind of conditions were present yesterday when the USS Greeneville smashed into the Ehime Maru.

"I’ve been in that situation," said Hartung, who lives in Port Orchard, Wash., 10 miles from the naval shipyard in Bremerton. "Here you are proceeding along and all of a sudden all hell’s breaking loose."

The periscope of the USS Permit punched through the hull of the freighter, followed by orders from the officer of the deck to dive the sub 100 feet toward the bottom to get out of the way, Hartung said.

"You’re trained not to panic," he said. "We just proceeded back down and made sure we were intact."

It’s possible that the Ehime Maru was sitting directly above the USS Greeneville yesterday as it rose to periscope depth, usually 56 feet from the top of the sub’s sail, said Michael Nahoopii, a Naval Academy graduate. Nahoopii, who retired from the Navy in 1995, was officer of the deck for the fast-attack sub USS Indianapolis when it was home-ported at Pearl Harbor before being decommissioned.

If the Ehime Maru’s engines were off, the Greeneville’s sonar would have trouble detecting the ship, Nahoopii said. The sub’s periscope can’t look directly above. And at the surface, bumpy seas can lap over the lens, making it hard for the officer of the deck to see any ships, Nahoopii said.

"There are checks to try and help you not hit someone," he said. "But if the weather’s rough, it can also affect sonar and you can’t see too well over the periscope. A lot of times trawlers have their engines off and you don’t hear any engine noise. Sailboats are really scary."

Guiding a nuclear-powered, fast-attack submarine to the surface of the sea can be the most stressful few minutes in the career of the lieutenant serving as officer of the deck. He has to have his eye glued to the sub’s periscope and ears tuned to any strange sonar contacts.

A choreography of commands and movements between the officer of the deck and the rest of the all-male crew in the sub’s control room is designed to bring both boat and men up safely.

So a collision such as yesterday’s is an almost unimaginable horror for the officer of the deck, Nahoopii said.

"While you’re deep underwater, you’re lucky," Nahoopii said. "The odds of running into anything are pretty low. The odds increase as you get to the surface. You start worrying about barges, sailboats and shipping vessels and everything else that could be up there."

The initial command to surface begins with the officer of the deck, who tells the diving officer to "go to periscope depth," often followed by the command "make your depth 5-6 feet."

Each order is repeated as the diving officer adjusts the sub’s rudders and elevators. The chief of the watch, usually a senior or chief petty officer, kicks in the blowers that pump air into the sub’s ballast tanks, forcing water out. The buoyancy combines with the nuclear-powered engines to nudge the sub toward periscope depth.

The sonar technician pipes the sounds through the control room’s speakers. The officer of the deck begins sweeping his periscope in circles.

"Dancing with the one-eyed lady," submariners call it.

"He’s spinning around looking up, looking all around for anything," Nahoopii said.

If bad weather throws off the sonar, Nahoopii said, the pressure on the officer of the deck increases.

At periscope depth, he makes three 360-degree turns with the periscope, sweeping the horizon for any blurry shapes or shadows. He switches the periscope back and forth between low and high power, checking every quadrant for anything suspicious.

If everything looks clear, the officer will announce, "No close contacts," followed by the command to surface.

As the sub rises, the officer of the deck’s eye never leaves the periscope. "That’s the key," Nahoopii said. "It’s all up to him.

As officer of the deck for the Indianapolis in 1990, Nahoopii had two fears: freak swells that have drowned lieutenants as they drove their subs from the outside cockpit, and hitting something while trying to surface.

A collision can mean the end of a Navy career, Nahoopii said. Submariners live in a highly competitive world where "you almost have to be perfect to make the next rank."

The officer of the deck, the person usually in charge, bears most of the responsibility, Nahoopii said.

"But ultimately, the captain is in charge," Nahoopii said. "Even though he may not have been there, he’s the one who has to make sure his people know what they’re doing."

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