Still, Carver seemed to know his stuff, and he deserved a chance. It wasn't his fault that his first tour aboard the Pittsburgh was taking him into a hot Kuril passage.
"These are the waters Flight 007 went down in, aren't they?" Latham asked.
"Not quite, XO," Chase replied. "Northern Sea of Japan. They managed to overfly Kamchatka and Sakhalin before the Russians finally got fighters up." Another piercing ping echoed through sea and hull. "I'd say they're a bit more on the ball up there, now, wouldn't you?"
PING….
"Captain?" Carver said. "Crossing the hundred-fathom line."
"Very well." PING….
The one-hundred-fathom line — six hundred feet — was the arbitrary topographical boundary marking the edge of the continental shelf. The shallows surrounding Kunashir, southernmost of the Kurils, humped up above the much deeper water to the west, averaging a depth at the top of about thirty to forty fathoms. But just beyond that flat-topped ridge, if they stayed on this heading, was a deeper channel… and a safe escape to the open Pacific beyond.
But a hundred fathoms wasn't much to work with… less than twice the Pittsburgh's 340-foot length. At thirty fathoms, the sub would be practically pinned in a shallow film of water half as deep as the boat was long. Submarines by nature were three-dimensional creatures, capable of taking advantage of maneuvers up and down, as well as ahead and back, port and starboard. Periscope depth for an LA-class boat was 52 feet; in water 180 feet deep, she wouldn't have much room to maneuver.
But the Russians would know the channels between the islands well, and would have them blocked by now, or worse, mined. Chase was taking a gamble, but a calculated one, trying to slip over the ridge and into the deep channel beyond halfway along the undersea valley's sinuous length.
If they could make it that far… another five miles…
"Conn, Sonar," a voice announced from the 1MC overhead speaker. "New sonar contact, designated Sierra Two-five, bearing zero-zero-six. Twin screws, estimate twenty knots, making fifteen turns per knot. I think it's another Krivak I, Captain."
"Very well." He looked at Latham. "That makes four Krivaks up there. They're eager."
"KGB Maritime Border Guard," Latham replied. "They're not usually this far out."
"Probably a blocking force stationed in the Kurils." He picked up a microphone and keyed it. "Sonar, Conn. Keep on 'em, Rodriguez. And keep a sharp ear out for any air traffic."
"Aye, aye, Captain."
Chase smiled. SM/2 Enrique Rodriguez, at least, was an old hand on the 'Burgh, and one of the best sonar men he'd served with. Rodriguez was one of those sonar magicians, men who could listen to the wash and rumble of sound in the ocean around them and extract information that seemed like the product of nothing less than witchcraft.
The Krivak I was an old sub hunter, her equipment long out-of-date. Likely, the Soviets were employing her as a driver, to chase the 'Burgh toward the real hunters astern, or else to serve as a barrier force to keep her penned.
"Conn, Sonar."
"Conn. Go ahead."
"New contact, designated Sierra Two-six, bearing three-five-zero. This one sounds like an aircraft, probably big and low over the water."
"Let me hear. Put it on the horn."
He heard it then over the speaker, a low, droning rumble, muffled by water and distance.
"Sounds like a big four-engine turboprop, Captain," Rodriguez added. "Not a clatter, like a helicopter."
"Thanks, Rodriguez. I want—"
"Conn! Sonar! Splashes close aboard, port and starboard! Sounds like sonobuoys! They're going active!"
A barrage of pings hit the Pittsburgh, each one a finger reaching down to touch the vessel and pinpoint its location to the surface hunters. The aircraft overhead must be an ASW plane, a May or a Mail, and the fact that they'd laid a pattern of sonobuoys suggested they were pretty sure exactly where the Pittsburgh was.
"Helm, come right to zero-nine-five," Chase said. "Make depth five hundred feet."
"Helm, right to zero-nine-five," Lieutenant Daly, who had the helm watch, echoed.
"Coming right to zero-nine-five," an enlisted man repeated. He was seated at the right-hand set of what looked like the control yoke and instrumentation for a commercial aircraft. The deliberate redundancy of orders repeated, then repeated again, was an essential part of submarine operational procedure, a way to check and double-check that the captain's orders had been correctly heard and correctly acted upon.
"Fifteen degrees down bow planes," Latham said. "Make depth five-zero-zero feet, aye."
"Fifteen degrees down bow planes. Make depth five-zero-zero feet, aye, sir," the planesman, on the left-hand yoke, repeated.
Chase grabbed the periscope walk stanchion as the deck tilted beneath his feet. They were already at 115 feet. For the next few seconds, Latham chanted off the depth figures from his readout. "Passing two-zero-zero feet, sir. Two-one-zero. Two-two-zero… two-five-zero… " And the Pittsburgh continued her long, silent descent into blackness.
"Sonar, Conn," Chase said into the mike. "Any sign of a layer we can hide under?"
"Conn, Sonar. Negative, sir. Not in these waters, not this early in the season."
Temperature inversions, a layer of warmer, less salty water beneath a colder, heavier layer, created a kind of barrier to sonar. The curtain wasn't opaque, necessarily, but a submarine had at least a fighting chance of shaking her echo-hungry pursuers by slipping beneath an inversion layer that channeled most of the searchers' sonar away from the target.
Unfortunately, the Sea of Okhotsk was cold, especially now, with its seasonal ice cap only recently melted. The upper layers were somewhat warmer than the lower, but the temperature was fairly constant top to bottom, the waters well mixed. There would be no help there.
"Sonar, Conn. What's the status on Sierra One-nine?"
"Conn, Sonar. Sierra One-nine bearing now zero-zero-two, Skipper. Heading one-eight-three, making turns for twenty knots. I estimate his range at nine thousand yards, sir."
That might work. Contact Sierra One-nine had arrived on the scene almost an hour ago. Rodriguez had identified her as a Kresta II class ASW cruiser, probably the Admiral Yumashev.
A Kresta II was big—521 feet in length and pulling an unloaded displacement of 6200 tons. She was also noisy, with her twin steam turbines and high-pitch screws. She was a dangerous adversary, with a powerful, medium-frequency sonar forward, and mounting RBU-1000, RBU-6000, and two quad launchers for the rocket-delivered torpedo NATO had designated as SS-N-14 Silex for attacking submerged targets.
But there might be a way of using her bulk and her noisy power plant. The Kresta was almost bow-on, bearing down on the Pittsburgh like an oncoming express freight.
"Leveling off at five-zero-zero feet," the planesman said.
"Captain, we are at five hundred feet," Latham announced.
"Very well. Helm, come left to three-five-eight degrees. Make turns for eight knots." That put them precisely on a reciprocal course with the Kresta; the two were approaching one another now bow-on, with a combined velocity of thirty knots.
"Helm left to three-five-eight, aye, sir. Making turns for two-zero knots." The litany of orders given, repeated, and re-repeated was like a kind of intricately and meticulously choreographed ballet. There was a sense of affirmation, of tightness, of certainty that had its effect on every man in the combat center.