'You'll just have to make them come forward, then,' Morse said.
'Concur, sir,' Bell said. 'But how?'
'We'll move forward briefly ourselves,' Jeffrey said, and give them something to shoot at — us.'
Bell opened his mouth to object, but Jeffrey held up a hand. 'Get ready to drop a wrench in the torpedo room, just to be sure.'
'Hydrophone line contact!' Voortrekker's sonar chief shouted. 'Now passive contact on the bow sphere as well! Direct path, relative bearing zero zero two.'
'At last,' ter Horst said.
'Contact classification?' Van Gelder said.
'Mechanical transient, sir. Some kind of machinery noise. Might have been a casualty in torpedo room equipment.'
'Indeed,' ter Horst said. 'So they've had some battle damage, or the crew's been worked past their endurance. Or both. What's contact range?'
'Sir,' Van Gelder said, 'distortion from the hot vents is impairing our ability to triangulate using the deployed arrays.'
'Give me your best guess of depth and distance,' ter Horst snapped.
'Extreme range, sir,' Van Gelder said, 'about sixty-five kilometers…For us to hear at all given ground masking effects, Challenger has to be above thirty-eight hundred meters. Conjecture that's her crush depth.'
'Or it's as far down as they want to push their luck today,' ter Horst said. 'Interesting.
Well, we'll just have to move in closer.'
'Sir,' Van Gelder said, 'that's risky and we'll lose the wires to the deployable hydrophones.'
'We must strike while we have the enemy localized, Number One. At nearly five thousand meters depth ourselves, if we simply wait here for much longer, the hydrophones might fail anyway.'
'Understood,' Van Gelder said.
'Don't worry, Gunther,' ter Horst said. 'As we get closer, we'll pick up Challenger on hole-in-ocean, long before they see us on their ambient sonar. Closing the range before we fire will cut the running time of our torpedoes, improve the odds of a kill even if the units get in a high-speed stern chase against the target.'
'Concur, Captain,' Van Gelder said.
'Zero zero two relative is three two three true,' ter Horst said. 'Helm, steer three two three. Slow ahead, twelve knots.'
'Aye aye…Turbine room answers slow ahead, making revs for twelve knots, sir.'
'Warm up the weapons, tubes one through eight,' ter Horst said.
'Warm up the weapons, tubes one through eight, aye aye,' Van Gelder said.
'Preset all weapons for maximum yield.'
'Maximum yield, aye aye.'
'Flood the tubes, equalize the pressure, and open the outer doors tubes one through eight.'
'Sierra 1 signal strength is increasing slightly,' Sessions said.
'That might just be from reduced particulate attenuation,' Ilse said, 'along our line of sight.'
'Or ter Horst might be coming closer,' Jeffrey said. 'We have to be sure…We need to triangulate, try to get cross bearings from another hot vent eyepiece.'
'That one eight hundred yards north of us might work,' Ilse said. Jeffrey studied the vent field map. 'Concur. Helm, ahead one third, make turns for four knots.' 'Mechanical transients!' Sessions broke in. ' Classification?' Jeffrey said.
'Many torpedo tube doors being opened.'
'How many is many?' Jeffrey said.
'Eight, I think,' Sessions said.
'All of them,' Jeffrey said.
1 HOUR LATER
'Still no new contact on the target,' Van Gelder said. 'What's range to their last known position?' ter Horst said.
'Now forty-five kilometers, Captain. Query going active for a precise range and bearing.'
'No,' ter Horst said, 'I think it's premature. They'd have a snap shot in the water before we even heard our ping come back.'
'Good,' Morse said. 'You've picked up Sierra 1 again. I'd suggest you shuttle back and forth, to keep updating the triangulated range and start a TMA. Now you've calibrated both eyepieces, the data reduction ought to go much faster.'
'I concur,' Jeffrey said. 'Helm, back one third, make turns for four knots. Return us to that other eyepiece vent location.'
'Back one third, make turns for four knots, aye,' Meltzer said. 'Maneuvering acknowledges back one third, making turns for four knots, sir.'
'Very well, Helm,' Jeffrey said. 'Now, people, listen up, we need to caucus…We have a problem. Our lure to bring Voortrekker toward our weapons seems to have worked, but now that she's in motion, she'll be harder for us to track, and she's been alerted.'
'But presumably they won't know about the hot vent lensing,' Bell said.
'So we hope,' Jeffrey said.
'Jan isn't likely to think of it,' Ilse said. 'He's not exactly in tune with the environment.'
'He has a crew, remember,' Morse cautioned, 'an XO and sonar experts and so on.' Ilse frowned and nodded.
'As long as they don't go active,' Jeffrey said, 'we may be able to fool them about our actual range.'
'Yes,' Morse said. 'When they hear the Mark 88s doing end-game runs without prior active searches, they'll guess at our range based on what they know of Challenger's sonar sensitivity, and underestimate. They'll probably launch a snap shot spread, a nuclear shotgun blast — they've done that twice already since making contact at Durban — but it ought to all fall safely short of us.'
'Concur,' Jeffrey said. 'So let's hope ter Horst doesn't go active. It would be a toss-up for him, revenge versus self-preservation, offensive accuracy versus his ping helping our own fish home in.'
'Oooh,' Ilse said, 'I wouldn't want to count on anything there, knowing Jan.'
'Mmph,' Jeffrey said.
'Sir,' Bell said, 'we have an improved range estimate to Sierra 1 now, still too far to engage. Target speed appears to be ten or fifteen knots. I am repositioning the units from tubes one and five to intercept based on the latest 3-D TMA.'
'What's target depth?' Jeffrey said.
'Fifteen thousand feet, sir,' Sessions said. 'The acoustic shadowing along the bottom is more than offset by ray path focusing at the intersection of the two big vent plumes, our main telescope lens.'
'Good,' Jeffrey said, 'just as we predicted.'
'But we still have a serious problem,' Morse said.
Jeffrey nodded. 'We were counting on using our Mark 88s for a slow-speed stealth attack against a more or less stationary target. Since Voortrekker's moving, they'll be much harder to hit, and our TMA will be rather crude with this lensing effect.'
'Plus there's the sonar reception time delay,' Ilse said. 'At thirty miles, say, until our torpedoes pick him up themselves and we can target directly through the fiber-optic wires, there'll be a half-minute lag between Challenger's latest raw data and where Jan actually is.'
'Correct,' Jeffrey said. 'So now the weapons will need to ping and make their end-game runs at high speed, from ten thousand yards away or more, and ter Horst will hear them coming. Against ceramic-composite hulls at this depth, Mark 88 warheads have a lethal range of only a nautical mile or so, two thousand yards. The enemy'll be able to counterfire low-yield warheads to intercept our incoming fish, and he'll spoil the whole attack.'
