Deep Sound Channel (7 page)

"The bubble energy fights back and forth with the water pressure?" Ilse realized now that everyone said "dot" instead of "point" for decimals—less ambiguous?

"In this case that's the fireball," Sessions said. "It's buoyant, hot as hell, so it comes up really fast. There's a nasty airborne shock wave when it breaks the surface."

"How hot is it?"

"Try ten million centigrade."

"Ouch."

"It dissipates, cooling on the way, but being underwater doesn't help."

"How come?"

"Compared to air, the hydrostatic pressure confines the blast, concentrates the fireball. The water boils, of course, but that won't carry off much heat. Seawater's got poor transparency too, from all the stuff that's floating in it—"

"Suspended particulates, organic matter . . ."

"Yeah, Ilse, you would know The whole photon flash

on detonation, the gamma rays and X rays, ultraviolet, visible and infrared, not to mention all the neutrons, they get held in close, strengthening the fireball. On the other hand, seawater does suppress the EMP, the electromagnetic pulse that fries unshielded circuits. . . . Anyway, first you have this giant burst of water, then you get the fireball. Timing between the two depends how deep the thing went off. There'll also be what's called the base surge, a kind of ground fog that spreads out like a fluid and evaporates, ocean surface atomized by the vicious shock wave through the water. You know an underwater blast's much more destructive to naval vessels than an airburst at a given distance. Water's much more dense and rigid, and sound travels five times as fast."

"How much fallout is there with a nuclear torpedo or, or a depth charge?"

"Nothing like an H-bomb used on land."

"But how bad is it?"

"Not counting any from the ships they hit?" Sessions said. "There're the weapon parts, of course, vaporized. Fish and plankton, what's left of 'em. And loads of radioactive steam, from carbon, sodium, trace metals in the seawater, by neutron activation."

"Tidal waves?"

"At least two surges," Sessions said, still watching his displays. "They subside eventually with the kind of warhead yield we're using."

"So they aren't like the big ones from an earthquake?" Ilse said. "Like that one in the Caribbean that wrecked your cruiser Memphis years ago?"

Sessions shook his head. "Then the thing's a meter high way out at sea, but moving literally fast as a jumbo jet, piling up murderously onshore. Nuclear tsunamis act more like ripples in a pond, except they're fifty, sixty feet from crest to trough. They die off, mostly, in a matter of miles."

"Can't big surface ships just ride that out in open water? I got caught on the edge of a typhoon once, on a research trip."

"Yeah," Sessions said, "assuming the enemy doesn't ripple fire or hit from several bearings at once. A ship's hydrophones will give some warning, if you don't receive it on the data links or see the fireball glow, and you can turn bows-on. Still one hell of a ride."

"I can imagine."

Sessions turned to face Ilse. "The worst is if you're close, caught by the blast itself, or lose propulsion from the shock and take a wave from off the beam that's any higher than you're wide. Busted open, capsized, either way you've had it."

"Warhead locks are bypassed," Jeffrey said. "Special weapon loaded in tube seven."

"Very well, Fire Control," Wilson said. "I am relaying the permissive action link code."

"Green light in the torpedo room," Jeffrey said. "PAL code is accepted. Weapon is enabled, armed guard has withdrawn."

"Very well, Fire Control," Wilson said.

From here Jeffrey knew the procedures were the same as were used with a conventional fish. To be fully armed, the warhead had to first be surrounded by seawater, then get an electronic signal, then feel the g-force of launch, then run out for a preset safety distance.

"Make tube seven ready in all respects," Wilson said. 'Tube seven, firing point procedures, area burst on Master 1 and Master 2."

"Solution ready," Jeffrey said. "Ship ready. . . . Weapon ready."

"Match generated bearings," Wilson said, "and shoot."

"Unit from tube seven fired electrically," Jeffrey said. "Unit is swimming out."

"Unit is running normally," Sessions said.

"Time to target?" Wilson said.

"Current range is fifteen thousand yards, sir," Jeffrey said. "We should detonate in ten minutes."

"Very well," Wilson said. "I intend to put some distance between us and our unit's track, but we'll do it stealthily and keep the layer between us and our quarry. Helm, make your course two six five, make your depth one eight zero feet."

"Aye, sir," Meltzer said.

"Captain," Jeffrey said, "since we're about to make one hell of a datum anyway, recommend we increase speed slightly to gain more track separation."

"Concur, Fire Control," Wilson said. "Helm, ahead one third, make turns for eight knots.

" Meltzer acknowledged.

"I intend to leave our towed array deployed," Wilson said.

"I concur, sir," Jeffrey said. "Sonar, there could be more enemy boats out there."

"Understood, Commander," Sessions said.

"Hull popping sounds on the towed array," Sessions said, "bearing three five five true!

Assess the transient as coming from Master 1."

"Interpretation?" Jeffrey said.

"More hull popping sounds on bearing zero zero five! Assess both targets are rising!"

"They're preparing to fire," Wilson said. "Will our unit intercept in time?"

"It'll be close, sir," Jeffrey said.

Suddenly Ilse saw Sessions sit bolt upright. "Water slug transient on bearing three five five! . . . Torpedo in the water! Incoming torpedo bearing three five five!"

"They heard our weapon after all," Wilson said.

"In time to launch a snap shot back at us," Jeffrey said. "Sir, recommend we move away from our unit's track more rapidly."

"Concur," Wilson said, "but first, fire a brilliant decoy toward the incoming torpedo." Jeffrey gave the orders.

"Helm," Wilson said, "take us back below the layer. Make your depth six hundred feet, make normal one-third turns and do not cavitate."

"Maneuvering acknowledges," Meltzer said.

"Chief of the Watch," Wilson said, "keep the fore-planes deployed—they enhance our maneuverability."

"Do not retract the foreplanes, aye," COB said.

"Lose the towed array. I don't want it tangling our stern and we don't have time to retract it."

"Shear off the towed array, aye."

"Second incoming torpedo," Sessions shouted, "bearing zero zero four!"

"Master 2 just fired at us," Jeffrey said.

"Chief of the Watch," Wilson said, "on the sound-powered phones, prepare for radical maneuvers. Helmsman, make a knuckle. Hard left rudder, make your course one six zero.

"

Ilse braced herself against her console as Challenger banked into the turn. Meltzer called out their course every ten degrees, finally announcing, "Steering one six zero, sir."

"Very well, Helm," Wilson said.

"Incoming torpedoes drawing left to right," Sessions said. "They're in passive search mode, sir."

"What kind are they?" Jeffrey said.

"Modified Russian propulsion systems, their export model VA-III Shkvals."

"Nuclear-capable platforms," Jeffrey said.

"We'll try to sneak away fast as we can," Wilson said, "see if our decoy draws them off. Helm, top quiet speed. Ahead two thirds, make turns for twenty-six knots and do not cavitate."

Wilson gave Meltzer a moment, then picked up the

MC. "Maneuvering, Conn, this is the captain. Stand by for high-speed operations." Ilse watched two bright lines cascade down Sessions' waterfall displays, gradually getting thicker. She could see a third line run between them, thinning out. Those are the torpedoes, she realized, theirs and ours.

"Unit from tube seven has detonated!" Jeffrey said.

"Did those contacts launch their missiles?" Wilson said.

"Not yet, sir," Sessions said.

"Chief of the Watch," Wilson said, "on the sound-powered phones, collision alarm." COB acknowledged.

But there was nothing, and Ilse was confused. Then she understood. The fiber-optic signal, through the wire, came at the speed of light. The shock wave traveled at the speed of underwater sound

Challenger rocked, shaking Ilse against her seat belt. A thunderous blast pummeled the ship, heard right through the hull. The mike coils jerked crazily from the overhead, and navigation instruments flew. A heavy brass divider crashed to the floor, one sharp point sticking in the fleshy part of Commodore Morse's ankle. Snow danced across the sonar screens.

"Loud explosion bearing three five nine!" Sessions said.

"No kidding," Ilse mumbled.

"Status of incoming torpedoes?" Wilson said. "Impossible to tell."

"Navigator," Wilson said. "Sounding."

"One three five zero zero feet, sir," the navigator said.

"Helm," Wilson said, "doctrine for our steel-skinned boomers says run shallow, but I want to take her deep. Make your depth ten thousand feet smartly." Ilse thought she'd heard wrong.

"Aye, sir," Meltzer said. "Thirty degrees down angle on the diveplane functions." Ilse gripped her armrests as the deck nosed down. Meltzer called out the numbers every hundred feet. They kept coming faster and faster and started getting much too large.

"Relax," Sessions said. "More depth helps squelch the blast." Ilse caught her own reflection in a console screen—her eyes were popping and she couldn't make them stop.

"Our hull's ceramic-composite alumina casing," Jeffrey said. "We're designed for this, Ilse. I guess now you need to know."

But knowing didn't help much, Ilse thought.

"Chief of the Watch," Wilson said, "disengage shallow water valves and pumping hardware, line up abyssal suite."

Another shock wave hit, not as hard but more drawn out.

"The surface echo from our weapon," Sessions said. Then another one went by, sharp but weaker still. "Bottom echo that time."

A third concussion hit, this one soft but snappy. "Fireball throbbing," Sessions said, " hydrostatic oscillation, damping coefficient is dot nine."

"I want to make another knuckle," Wilson said. "Keep those inbound torpedoes on our quarter, starboard side instead. Let's confuse them with some bearing rate. Helm, hard right rudder, make your course two zero zero." Again the ship banked hard. Sessions whispered, "That'll force their seekers to keep leading us. They can't just ride up our wake turbulence and then we get it in the ass."

"But aren't we blind that way," Ilse said, "without the towing sonar?"

"We've got partial baffles coverage from the wide-aperture arrays."

"Fire a noisemaker," Wilson said. "Fire another decoy onto our previous course." Jeffrey relayed orders to Weapons Control to launch the decoy in tube six.

"Fire an acoustic jammer, starboard side," Wilson said. "Reload tubes five and six, more brilliant decoys."

"Reverb is clearing somewhat," Sessions said. "One incoming torpedo, bearing three four five and constant, depth three thousand feet. It's ignoring the countermeasures. Doppler says it's gaining on us."

"What's the range?" Jeffrey said.

"Fourteen thousand yards."

"Fire Control," Wilson said, "fire two more noisemakers."

"Sir," Jeffrey said, "we're too deep now for noisemakers."

"Then fire another active decoy, shallow running on a reciprocal course. Program hullpopping and cavitation sounds, with a ten-decibel step-up from nominal." Once more Jeffrey went to work.

"How close is too close?" Ilse whispered.

"If it's dot one KT like ours," Jeffrey said before Sessions could answer, "at this depth and with our hull, at two thousand yards of lateral separation we're a mission kill for sure, outright dead if you believe the pessimistic calculations."

"Time to lethal range?" Wilson snapped.

Sessions punched more keys. "Eight minutes if we can't lose it, less if it's a larger warhead. . . . It's got passive lock, it stopped wigwagging!"

"Locked on us or on the decoy?" Jeffrey said.

"On Challenger, I think. . . . Yes, confirmed, our initial decoy's failed, a machinery implosion."

"How's that torpedo tracking us?" Wilson said. "Do we have a sound short?"

"Negative, sir," Sessions said. "It must be catching re-verb off our stern. It's still incredibly noisy out there. . . . Torpedo's first-stage pump-jet has switched to end-game speed!"

"Then we're committed to a dead heat now," Jeffrey said.

"Helm, ahead flank smartly," Wilson said.

Meltzer reached for the engine-order dial and flicked it several times. More transients appeared on the sonar screens, making Ilse jump.

"That's us," Sessions told her as he forced a smile. "The reactor coolant check valves just slammed into their recesses."

"Chief of the Watch, flood negative," Wilson said. "Add some weight to pick up speed." The ship continued diving. Ilse eyed her screens. Fifty-one knots downhill through the water. Fifty-two. The ride was rough.

"Sonar," Wilson said, "did we get those two 212 boats?"

"Can't tell yet, sir. No flooding or implosion sounds were heard above the blast."

"Captain," Jeffrey said, "recommend we go active, search for metallicity inside the bubble cloud."

Wilson nodded. "One ping, maximum power. The whole sector knows we're here." Ilse heard a double buzz, and several crewmen held their ears. Then there was a sharp and high-pitched eeeee, deafening, not at all what she expected. Yet the sonarmen in headphones once again seemed unconcerned. Automatic amplitude filters?

The echoes came back in several seconds. Sessions put the data through his signal algorithms. "Commander Fuller! We have two distinct clouds of falling matter, diffuse, well separate from each other. I assess both targets as destroyed!"

"Status of incoming torpedo?" Jeffrey said.

"Range twelve thousand yards, depth decreased but now it's diving again. . . . It went right past the latest decoy."

"The blue-green laser target discriminator," Jeffrey said. "It's even better than we thought."