Deep Sound Channel

by Joe Buff

  "Engage terrain-following cruise mode, aye aye, sir." "We'll head south at top quiet speed," ter Horst said. "Helm, half ahead, thirty knots."

  "Half ahead, thirty knots, aye aye, sir. . . . Turbine room answers steam throttles set for half ahead, making revs for thirty knots, sir."

  "Number One," ter Horst said, "once you see that message buoy off, you take the conn. I want to do a walk-around inspection of our running repairs, speak to the crew in small groups as well. Then I plan to take a nap. . . . Have me awakened in four hours and I'll relieve you. Then you get some rest yourself. Gunther, you look tired." 12 HOURS LATER

  Jeffrey's head jerked upright and he realized he'd been dozing at his console, after hours of poring through the on-line sonar technical manuals. It all came down to who would have the better first-detection range, Challenger or Voortrekker. He'd hoped for inspiration somewhere in the circuit diagrams, but Jeffrey's muse had most cruelly abandoned him.

  He noticed that Commodore Morse was standing in the aisle—that must have been what woke him.

  Jeffrey rubbed his eyes and looked at Bell, who had the conn. "Any contacts?"

  "Nothing, sir," Bell said. "We thought it best to let you sleep." Jeffrey glanced at a chronometer. He'd been out for forty minutes. "Boy, do I need to take a leak."

  "So do I," Morse said. The two men headed aft. "I just finished visiting the wounded," Morse said.

  Jeffrey chided himself. "One more thing I didn't think of." Morse waved dismissively. "The men all understand. You're working very shorthanded."

  "How's the captain?"

  "The corpsman let me talk to him for just a minute. I told him you're doing a great job. He said he wasn't surprised."

  "I should stop in," Jeffrey said as they entered the empty CO state-room.

  "Don't," Morse said. "He's out again. His brain's swollen, you know. That's what a bad concussion is—tissue abraded against the inner skull ridges. Needs time for all his neurons to get back to normal. Total rest, so let him be."

  Jeffrey noticed that Wilson's family pictures were gone from his desk, presumably moved next door to be with him. Jeffrey deferred to Morse, who used the head first. When it was Jeffrey's turn, he glanced at himself in the mirror. He needed a shave and his cheeks looked pale and jowly. He wondered if that was fatigue, or middle age coming on early. He tried to imagine how he might look with a moustache. Where did that come from? he asked himself.

  When he'd done his business, he and Morse lingered in the captain's quarters.

  "How's Monaghan doing?" Jeffrey said.

  Morse sighed. "As well as can be expected, they told me. He regained consciousness for a little while, was actually communicating by Morse code using his eyelashes, since they have the respirator hooked up through his trachea."

  "That's clever," Jeffrey said. "Who thought of Morse code?"

  "Monaghan did. Took the SEAL a minute to catch on. But then he went into a coma. His blood gases don't look very good. We need to get him proper care and quickly."

  "I know," Jeffrey said. "He has four kids."

  "The engineering staff used spare parts to jury-rig a shock gimbal for his litter, so at least he's protected from further mechanical stress."

  "Good," Jeffrey said. "Lieutenant Willey's initiative always has impressed me."

  "You'll be glad to learn Ilse's friend Otto is well cared for

  too. COB made the arrangements, in his role as your master-at-arms. Our fiendish EPW

  is under guard by at least two people at all times, one officer and one enlisted."

  "Just like an atom bomb," Jeffrey said.

  "He's trussed up nice and snug so he can't harm himself."

  "Where are they keeping him?" Jeffrey said.

  "A storage compartment next to the goat locker," Morse said. Jeffrey knew that meant the chiefs' office and berthing area. "For a while," Morse said, "they had him on display in the enlisted mess."

  "You're kidding," Jeffrey said. He laughed.

  "No. The lads took to rubbing his head for luck. Seemed like he was going to have a stroke, though, so they had to put a stop to that."

  "Morale's all right, then?" Jeffrey said.

  "Clayton and his boys told everybody about you and that shark. Plus whatever else they could talk about. Seems your stock is high among the crew now, Mr. Fuller."

  "It's hard to believe all that was only yesterday," Jeffrey said. He and Morse started back to the CACC.

  "I also took a little walking tour," Morse said, "into the spaces I'm allowed. Told people what it was like back in my last war, the olden days in Her Majesty's Submarine Conqueror. Seemed to help relieve some of the tension."

  "Thanks, Commodore," Jeffrey said. "I don't know what I'd do without your help."

  "I'm sure you'd manage," Morse said, "just with considerably greater difficulty." He chuckled. "I told your men about the time we almost hit an uncharted seamount south of the Falklands because our charts went back to 1777, and how our trailing wire antenna once got tangled in the screw. How we had to surface and send divers over the side while rather vengeful Argie fliers might have found us any moment."

  "Puts current things in perspective, doesn't it?" Jeffrey said. They'd arrived back at the command console. Jeffrey sat again, eyeballing the navigation and gravimeter displays. The boat was at 11,750 feet, making twenty-six knots on base course 192, well masked by the rugged terrain.

  "Anything yet?" Jeffrey said.

  "Still no hostile contacts near our depth, sir," Bell said. "We're threading a series of repeatedly branching fissure canyons now, using a path through the whole complex I picked at random. It was Miss Reebeck's idea. Makes it very hard for someone else to guess which way we'd come."

  "Terrific," Jeffrey said.

  "Recommend we stop and drift again in another fifteen nautical miles," Bell said, "to listen when we reach this ridge." He pointed to a bunching-up of topographic contours on the bottom chart.

  "Concur," Jeffrey said, bending over to read the screen. "If we cruise in a slow circle when we get there, we'll be able to scan in all directions using the bow sphere and both wide-aperture arrays, get the best sensitivity possible on all bearings and frequencies. Our crinkled bow cap's interfering flow noise stops whenever Challenger does."

  "Understood," Bell said. "We're still at a real disadvantage, sir, when we approach the choke point. To get away we have to move. Voortrekker can just sit there."

  "I know," Jeffrey said.

  Jeffrey turned to look at Ilse. She was dozing at her station, a wrapped towel forming a kind of pillow to cushion her head against her shoulder. She was snoring softly, as were several others in the CACC.

  "I think she's rather cute while she's asleep," Morse said.

  "Foxy too," Bell said, giving Jeffrey a suggestive look.

  "Cut it out, guys," Jeffrey said.

  "No," Morse said. "You're not getting any younger, Jeffrey."

  "Come on," Jeffrey said, "we're in the middle of a battle, in the middle of a war." He glanced at Ilse again, his eyes staying on her longer this time. Her features seemed softer than when they'd first met, and in sleep she wore a peaceful smile. Jeffrey went back to his screens, once more studying the terrain that lay ahead around the choke point, trying to imagine where Jan ter Horst would hide, where he would pounce. Jeffrey wracked his brain over how Challenger could possibly get in the first detection, on Voortrekker rather than a salvo of her nuclear torpedoes inbound at high speed on the last part of a dogleg.

  Sonar superiority, Jeffrey told himself. How can we possibly achieve sonar superiority?

  4 HOURS LATER

  Ilse was studying the terrain around the choke point. Beside her Jeffrey and Sessions were going over sonar hardware specs and signal processing algorithms. Neither man looked very happy. Suddenly there was a distant rumble.

  "Transient's classification?" Lieutenant Bell called from the command console. Sessions quickly reconfigured his displays. "Nuclear explosion, sir. Bea
ring three three seven, wide-aperture array gives range approximately fifty-five nautical miles." Then another one went off. "Ten miles further away from us, sir," Sessions said, "on bearing three two nine."

  Ilse heard a third sharp rumble, mixing with the dying echoes from the other two. "That one was much closer," she said.

  "Affirmative," Sessions said. "Range thirty-five nautical miles, relative bearing three three four."

  Jeffrey stood. "Off the port bow," he said, "between us and the choke-point hump. Sonar, what was warhead yield?"

  "Working on that, sir," Sessions said. Ilse watched as he conferred with his staff. " Estimate each at about one kiloton, Captain."

  "Very well," Jeffrey said. "Fire Control, your thoughts."

  "One KT sounds small for depth bombs, sir," Bell said.

  "Concur," Jeffrey said. "That's more the size of an Axis torpedo warhead. . . . Sonar, can you tell the detonation depth?"

  Ilse worked quickly with Sessions on a refined estimate.

  "Depth in each case was about twelve thousand feet," Sessions said.

  "It's Jan, isn't it?" Ilse said.

  "Yeah," Jeffrey said. "He's not trying to create a cordon. The warheads were set off too far apart, and they don't lie on a straight line or an arc."

  "They aren't on a single bearing from any particular firing position either," Bell said, "so he didn't shoot a spread at a suspected contact with uncertain range."

  "Concur," Jeffrey said, "and he wasn't working from one good TMA, leading a moving target. He'd've had to launch those weapons half an hour apart to put the furthest torpedo that far out and then have simultaneous blasts."

  "Concur, sir," Bell said.

  "Voortrekker's expended an awful lot of nuclear torpedoes since making contact with us," Sessions said.

  "At least half a dozen to our one," Jeffrey said. "We only have three left now, so you'd think they'd start to run low too, even fresh from reprovisioning at the bluff."

  "That's the whole point," Ilse said. "Jan's making sure we know he's there, somewhere in front of us, and

  taunting us by visibly wasting ammo. He's messing with our minds." 2 HOURS LATER

  Ilse and Jeffrey were grabbing a quick bite in the enlisted mess, visiting with the crew, released from general quarters a few at a time so they'd be in top form later. Bell had the conn again and knew where Jeffrey was.

  One man finished eating, then lit a cigarette. Ilse bummed one off him—she didn't smoke but really needed one right now. She took a deep draft and then the both of them exhaled, blowing toward the overhead.

  She saw Jeffrey give her and the crewman a funny look.

  "Sorry, sir," the crewman said, "I'll put it out."

  "What?" Jeffrey said. "Oh, no, no, that's okay. It's just that, urn, uh, you two gave me an idea." Jeffrey seemed to stare off into space. "Yeah," he said, "this just might work."

  "What just might work?" Ilse said.

  "It'll take a lot of careful effort," Jeffrey said, "and luck. Heavy-duty calculations, Ilse, using every bit of data that you've got. Conditions have to be perfect, and the whole thing might backfire. . . . Hmmm. . . . We might not have the vertical directivity to filter out the noise, and there might be too much Doppler distortion along the line of bearing."

  "What are you talking about?" Ilse said, trying to stifle her annoyance, reminding herself Jeffrey was acting captain of the ship.

  Jeffrey looked at her and grinned like a little boy. "I'll explain it on the way." He stood up. "To the sonar consoles!"

  "You said there were hydrothermal vents around the choke point," Jeffrey said as they rushed down the nar-row, bending companionway and past some enlisted berthing spaces.

  "That's right," Ilse said.

  "Active ones?"

  "Yes."

  "They give off heat, right?" Jeffrey said.

  "Of course."

  "And they spew dissolved minerals."

  "That's what makes black smokers smoke," Ilse said. "Sulfides and sulfates precipitating when the superheated water meets the ice-cold ambient ocean."

  "The precipitation builds up to make the chimneys," Jeffrey said.

  "And it feeds the archaea and the tube worms," Ilse said.

  "But it doesn't all precipitate out, right? Some stays dissolved?"

  "Sure," Ilse said as they went up a steep ladder. "You can detect trace chemicals miles away sometimes, like helium 3."

  "So the water isn't only hotter," Jeffrey said, "it has greater mineral content, like having higher salinity." "Yeah. So?"

  "Don't you see?" Jeffrey said. "Horizontal and vertical thermoclines and haloclines, in the megaplume above a vent!"

  "Oh," Ilse said. "I, I do see what you're getting at. . . . Acoustic lensing."

  "Right," Jeffrey said. "Sound refracts away from water with higher speed and toward water with lower speed, and higher temperature and more dissolved minerals both mean higher speed. Each vent plume acts like a concave lens. It makes sound rays diverge."

  "Urn . . . I concur."

  "And they occur in fields," Jeffrey said, "the vents do."

  "Sometimes," Ilse said.

  "If you have two vents near each other, the place between them acts like a convex lens, like in a magnifying glass."

  "I guess that's true," Ilse said as they reached the CACC.

  "Sonar superiority," Jeffrey said. "With lenses we can make a telescope." 1 HOUR LATER

  Jeffrey checked the gravimeter again. Challenger was following the side of a long escarpment on the east edge of a caldera, a huge bowl of volcanic origin.

  "Torpedo in the water at our depth!" Sessions hissed. "Bearing three five nine, drawing left to right and closing, an inbound spiral course of unknown origin!"

  "Range?" Jeffrey said, his heart pounding now.

  "Bow sphere contact only! Signal strength implies about ten thousand yards, approach speed seventy knots!"

  "Right in our face," Jeffrey said. "No data for a snap shot at Voortrekker, and if we turn away, we just make a better sonar target for that fish."

  "Concur, sir," Bell said.

  "Countermeasures and AT rockets are useless this far down," Jeffrey said. "Their exhausts are strangled by the pressure."

  "Decoys and UUVs won't function either, sir," Bell said. "They'd implode right in the tubes the minute we equalize."

  "Phone Talker," Jeffrey said, "quiet collision alarm." "Quiet collision alarm, aye, sir."

  "Helm," Jeffrey said, "all stop." He didn't wait for Meltzer's answer. "Fire Control, make tube three ready

  in all respects including opening outer door. Set lowest yield, dot zero one KT. Ter Horst might not know our range, so swim the unit out."

  "Dot zero one KT," Bell said, "and swim the unit out."

  "Tube three," Jeffrey said, "firing point procedures on the incoming torpedo. Intercept and detonate the unit through the wire. Match sonar bearings and shoot."

  "Set!" Bell said. "Stand by. . . . Fire! Tube three fired electrically."

  "Unit is running normally," Sessions said.

  "Chief of the Watch," Jeffrey said, "stationary dive, rate of descent five hundred feet per minute."

  "Stationary dive, aye," COB said, "five hundred feet per minute, aye. No maximum depth specified."

  "Time to weapon intercept?" Jeffrey said.

  "Two minutes," Bell said.

  "How did he find us?" Jeffrey said.

  "I don't know, Captain," Bell said.

  Jeffrey eyed the displays. Do a one-eighty at the base of the escarpment and run back into God knows what? Voortrekker could easily have another torpedo lurking there. Turn to starboard instead, course 270, into the caldera that went far down past Challenger's crush depth? Rise and head to port and wind up naked against the escarpment crest, a dead setup for another shot? Ter Horst chose his ambush well. How did he find us?

  "Helm," Jeffrey said, "the moment our unit detonates go to ahead full smartly, then use hard right rudder."

  "Upon det
onation go to ahead full smartly hard right rudder, aye."

  "Course, Captain?" Bell said.

  "Two seven zero and follow the bottom." The caldera. "Sir," COB said.

  "Yes," Jeffrey said, "but it's the last thing he'll expect and he'll lose us in the reverb from these slopes."

  Jeffrey saw Bell punch the button to fire the warhead.

  The cataclysmic shock broke fluorescent light bulbs everywhere. Something threw Challenger backward and pressed her down.

  "That explosion was too strong," Jeffrey said. "They must have detonated the torpedo as our own weapon came up to it."

  "Confirmed!" Bell shouted. "Our unit did not detonate!" "Clever bastards," Jeffrey said.

  "Maneuvering acknowledges ahead full smartly!" Meltzer said. "My rudder is hard right!" Challenger banked to starboard.

  A reverberating shock wave hit and the starboard list grew sharper. The boat put on a nasty forward trim.

  "Sir," COB shouted, "our depth is fifteen thousand feet!"

  "Sir," Meltzer yelled, "we're in a snap roll from that reverb catching the sail! Without bowplanes I do not have control of the boat!"

  "Helm," Jeffrey said, "disengage fly-by-wire and work manually on hydraulic backup. Try to get us out of this uncoordinated turn."

  "Understood," Meltzer said.

  "Sir," COB said as he helped Meltzer, "our hull's so compressed we're losing buoyancy. I'm having trouble compensating even with the pumps lined up in series." Before Jeffrey could answer there was a crackling crunch from all around, then a nonstructural weld in the port-side CACC bulkhead snapped.

  "We're squashing inward," Jeffrey said. The depth gauge showed 15,200 feet. The pressure gauge showed 450 atmospheres. "If we do an EMBT hydrazine blow now, it'll take forever to work and we'll be helpless once it does, a sitting duck."

  "Sir," the phone talker said, "torpedo room reports heavy misting round the tube eight door repairs." At this

  depth, Jeffrey knew, the bilge pumps couldn't possibly keep up with a major leak, and at this depth any leak was major.

  "Captain," Ilse shouted. "Look at the gravimeter!" Jeffrey saw the image on his screen, the wall of the

  escarpment. It was shimmering, starting to give way. "It's an underwater landslide!" Ilse said.