"Commander, you know as well as I do decompression's a stochastic process. There're always people who show random hits not predicted by the data. The problem you've got is all the scarring in that leg. It doesn't fit well with any of the tissue compartment models that crank out the navy diving tables."
"So now what?" Jeffrey said. He reminded himself that two deep dives in a short period was especially risky.
"I'm giving you this painkiller. I'll check with you in half an hour. If the leg still hurts, you go into your rack and go on oxygen. Any twitching or slurred speech, dizziness or discoordination, you go into the hyperbaric chamber."
"Just what I need right now," Jeffrey said, swallowing the pill. He washed it down with coffee.
The corpsman looked Jeffrey in the eye. "Don't take chances with your health, Commander." He left the CACC.
Jeffrey went back to studying the LMRS downlinks. All of a sudden the bioluminescent glow flared up, much brighter than its background level. Then a big shadow seemed to cross the field of view.
"What the hell was that?" Jeffrey said. "COB, catch up to it, bring the LMRS closer."
"Bring the LMRS closer, aye." COB worked his joy stick. "I'm getting buffeting," he said. "The contact's not just drifting, there's wake turbulence."
"Sonar," Jeffrey said, "what's ambient Doppler show? Vortices from fins and flukes? Ilse, can you help?"
"Look at this," Ilse said. She relayed Jeffrey a false-color picture of the turbulence. It had a circular cross section.
"Pancake eddies," Jeffrey said. "Enemy sub! Designate the contact Master 26! TMA team start a plot!"
"She must be leaving on patrol," Wilson said.
"More likely a quick sortie to get her arse away from the next incoming A-bomb," Morse said.
"It's a diesel boat on batteries," Sessions said. "It's too quiet to be nuclear."
"COB," Jeffrey said, "don't lose it. Put the LMRS in trail, right in her baffles!" Jeffrey grinned, forgetting the pain in his leg. "Captain, we can follow Master 26 right out to sea."
The air in the control room still smelled very foul, even after three days of round-the-clock repair work and a jury-rigged new forward fan room installation.
"Synchrolift rolled out against the detents," Van Gelder said. "Outer subsurface blast doors closed behind us. Captain, we're ready to blow negative and get under way."
"Very well," Jan ter Horst said. "Bring us up ten meters smartly." Van Gelder passed the orders, in his role as diving officer when leaving port. He watched Voortrekker's depth decrease and hold. The pressure gauge declined by one bar exactly. The Agulhas Current caught the ship at once.
"Slow ahead," ter Horst said, "make revs for seven knots." Again Van Gelder passed the orders and the helmsman acknowledged.
"That's fast enough to not waste any time," ter Horst said, "in case the Allies try to hit the bluff again. Not that ground-penetrator gun bombs would get through all the layered armor under the hostage camps, but we better hope the next one doesn't go off underwater."
"It seems less and less likely there'll be another blast, Captain," Van Gelder said.
Ter Horst harrumphed sarcastically. "Either that or they know they missed and they want to get us lulled before the next one! Seven knots lets us stay quiet and at this depth avoids a surface wake — no need to draw attention to ourselves. It also gives that Daphne-class pig boat a chance to draw ahead."
"Er, I concur, sir," Van Gelder said, abashed.
"Port ten degrees rudder," ter Horst said, "steer two zero five."
"Aye aye," Van Gelder said. "Steering two zero five, Captain."
"Very well," ter Horst said. "Stand by for the Umlazi halocline."
"Helm," Wilson said, "left standard rudder, make your course two zero five."
"Left standard rudder, make my course two zero five, aye," Meltzer said. In a few moments Jeffrey heard, "Steering two zero five, sir."
"Very well, Helm," Wilson said.
"Commander," Ilse said, "we should be coming to another halocline. Salt content will decrease about two parts per thousand seawater."
"Very well, Oceanographer," Jeffrey said. "Helm, can you compensate for decreased buoyancy with up-angle on the sternplane functions?"
"Not the way she's been handling, sir," Meltzer said, "not at this speed without the bowplanes. We'll have to run the low-rpm variable ballast pumps."
"Very well," Jeffrey said. "COB, at your discretion."
"Adjusting buoyancy with quiet centrifugal variable ballast pumps, aye," COB said. "Ilse, you can't imagine how much it helps to know a halocline's coming. Sometimes when we hit one, it's like being in an elevator and the cable broke."
"It's quieter this way too," Jeffrey said. "We can do the pumping gradually."
"You're welcome," Ilse said.
Jeffrey watched Challenger's depth decrease and her nose come up slightly. Then she dropped back down to proper depth and trim as she entered the less salty water bowfirst.
"You're an artist, COB," Jeffrey said.
"This boat's a work of art," COB said.
At $3.7 billion, the most expensive SSN in history, she better be, Jeffrey told himself. Challenger's construction drew on quality control standards so demanding Admiral Rickover himself would've been jealous. Defense analysts in the know had called the new ceramic fast-attack boats an RMA, a revolution in military affairs, one of the most important advances in undersea warfare since the advent of nuclear propulsion and deterrent strategic missile subs. Jeffrey knew the pressure was on to prove his vessel's worth, or there might never be another in the U.S. Navy, even if the good guys won this war.
"Captain," Jeffrey said a minute later, "something's been preying on my mind."
"What's that, Fire Control?"
"The ISLMMs, sir, the improved sub-launched mobile mines," Jeffrey said. "With respect, I want to recommend again that we deploy a few."
"XO, I agree with you completely that it'd be great to sink some Axis shipping, since we've paid the price of admission to the bastion. But our top priority must be an undetected egress."
"But that's the point, sir," Jeffrey said. "If you think about the mission overall, it's not specifically an undetected egress that we want. What's required is the enemy not draw some connection between our presence and the Umhlanga Rocks event."
"Go on," Wilson said. Looking around, Jeffrey realized he had Commodore Morse's full attention too.
"It's a gamble to assume we'll get away without being detected," Jeffrey said.
"Granted," Wilson said.
"Submarining's a business of calculated gambles," Morse broke in. "If you don't feel your gut twisting, you're probably not doing your job."
"Then consider this calculation," Jeffrey said. "We're using a safety lane to escape. We might be spotted doing it. We may have been spotted already, for all we know. We have no way to tell since they'd ignore us. But, records of the detection would be made, even if unwittingly, in submarine deck logs and surface-unit Combat Information Center data, and sonar tapes and so on."
"Concur with that part," Wilson said.
"That means the opposition could eventually reconstruct that there was an extra submarine, us — that we were present and we weren't one of theirs."
"Oh dear," Morse said. "I think I see where you're going with this."
"The point is," Jeffrey said, "if we plant some mines, we're offering the Boers a red herring, an excuse or reason for us to have come by. That way when they investigate the nuclear explosion, their paranoia can still run wild. The board of inquiry can find it credible that we were in the area by coincidence, and then they start the purge we're hoping for."
Wilson actually smiled. "Very finely reasoned, Mr. Fuller. You're saying it's actually the lesser of two risks to launch some mines, in the bigger picture."