by Larry Bond
Passive sonars could hear lots of things: the sound of propellers as they cut through the water, the sound of a sub’s machinery, even the sound of water flowing over the hull. In Memphis’ case, with her port main engine down, her remaining machinery had to work harder—and that translated into more noise.
Boyd relayed, “Control wants to know the status of the Manta.”
“Fully charged and prepped,” Jerry replied as he checked the status window on the display console. His men had automatically readied the Manta, but Jerry didn’t expect the UUV to be launched. Right now, it was all about moving, getting away. The Manta, useful as it was, didn’t have the speed or endurance of a nuke. Once it was launched, it was a liability, unless they decided to abandon it.
“Control says the contact is close aboard, slow right drift,” Boyd reported.
And if they launched it, the latches would create a transient, a noise that would appear briefly on any sonar display and then disappear. Lots of things could create transients: flushing a toilet or changing depth. They not only made you more detectable, they signaled to the other side that you were doing something.
In control, Hardy was busily trying to get a handle on the rapidly developing situation while Bair got the fire-control party organized. Men moved about hurriedly as they took their seats at the fire-control system, or pulled out fresh plotting paper and began recording the sonar bearings to the contact.
“Now what?” demanded Patterson as she ran into the control room.
“I’m sorry, Doctor, but I don’t have time for a detailed explanation right now. We have a Russian sub on top of us, and I don’t think this is an accident. The best place for you is in your rack,” stated Hardy firmly.
“They wouldn’t attack now. We’re in international waters . ..”
“Doctor! Joanna, please go to your stateroom.”
Silently she nodded and slowly walked back toward her quarters.
“Conn, sonar. Transients from sierra nine one.”
“Sonar, conn aye,” replied Hardy.
“Conn, sonar! Torpedoes in the water! I repeat: torpedoes in the water!”
“Helm, right full rudder. All ahead standard. Launch decoys,” barked Hardy.
Jerry’s heart turned to ice with the announcement and he reflexively grabbed hold of a bracket and spread his feet apart. He needed the handhold as the deck tilted sharply to starboard and the hull vibrated with power. Hang the noise. It didn’t matter any longer.
Doctrine said to turn sharply, increase speed and drop a torpedo countermeasure as you go. At close range, you wanted to get outside the acquisition cone, the field of view of the enemy torpedo’s acoustic seeker. But where were they? Had they acquired Memphis? Probably not yet, but would they? Depth charges were different. They were brutal, but you didn’t have to wait. With a homing torpedo, there was time to get really scared as they closed. And they would only explode if they hit you.
Boyd’s next message surprised Jerry. “The Captain says launch the Manta immediately.”
Jerry glanced at the course and speed repeaters as he put on the phones. They were building up speed and were already over ten knots. The safe limit was five. Jerry put on his headset and started the launch procedures.
“Mr. Mitchell,” Hardy ordered over the circuit, “I won’t slow down Memphis, but I need the Manta out there.”
Jerry mentally threw the operations manual into the bilge and started hitting keys on the panel. “Aye, sir. Launching in thirty seconds.”
As he set up the launch, Jerry, along with everyone in the room, heard a rushing roar that reminded him of a jet fighter flying past.
“That was a torpedo,” Foster announced amazingly calmly. “And close, too. The Captain got the decoys out just in time.”
“Tell me when you’re clear,” Hardy ordered over the circuit.
The problem with launching the Manta at speed was Memphis’ upper rudder. It could clip the slowly-moving UUV as it left its cradle on the aft deck. He also wasn’t sure how the fast-flowing water would affect the Manta as it was released. If the latches were slower on one side or the other, the UUV could be rolled or pushed into the hull.
So he dumped as much ballast out of the Manta’s trim tanks as he could and overrode the launch program. Instead of automatically taking station five hundred yards off the beam, Jerry programmed the Manta to immediately climb and go into a sharp starboard turn.
Hoping it was enough, he reported, “Launching,” into the phones and punched the release. The display showed the Manta’s attitude, and he watched it closely as the latches opened, a little more unevenly than usual, and the nose of the vehicle caught the water flow. It rose so sharply that he had to correct with a full down command or the vehicle might have flipped over. It wasn’t designed to do that. Of course, it wasn’t designed to be launched at this speed, either.
Jerry saw the Manta rise quickly and the starboard turn started just as Memphis turned hard to port, separating the two vehicles.
“Current bearing to sierra nine one is two four three degrees true.”
Jerry acknowledged and turned to the southwest. The Manta’s active and passive sonars both saw the Russian sub and the active sonar was sharp enough to see the Russian’s torpedoes. He reported, “Confirm sierra nine one at two four three degrees, range three four hundred yards. The weapons bear one seven zero and one four zero, both appear to be turning.”
“Then get them away from us, mister. Head southeast and drop a torpedo countermeasure.”
“Captain, the Manta only has one Mark 3 countermeasure left and two Mark 4 decoys.”
“Understood. Carry out the order, Mr. Mitchell.”
“Aye, aye, sir.”
Understanding Hardy’s intentions, Jerry sent the UUV between the torpedoes and Memphis, heading south-southeast at best speed. He wasn’t sure where the Russian torpedoes were headed until he’d tracked them for a minute, but they were still searching for their target. With the Manta’s acoustic intercept receiver, he could hear the Russian torpedoes as they pinged, still at a long-interval search rate.
The torpedoes occupied most of his attention, but Jerry also kept his eye on the Russian sub. It was speeding up, the passive display brightening as the sub made more noise, and as he watched, a huge spike appeared on the boat’s bearing. He could see the Russian sub changing course sharply to port, turning toward the north.
“Conn, sonar, Sierra nine one has released a countermeasure. He’s zig-ging to port!” announced the sonar supervisor. “He’s increasing speed, turning away hard. It looks like a torpedo evasion maneuver.”
“But we haven’t fired.” Jerry protested.
“It’s the Manta’s sonar,” the supervisor answered. “Its frequency is too high to be a normal U.S. active search set, so they think it’s a torpedo seeker.”
“Which means they think we’ve counterfired.” Hardy concluded. “We’ll use the time to get some distance between us. Mr. Mitchell, I’m taking Memphis northeast. Get those weapons away from us and then see if you can confuse the Russian sub some more.”
During the discussion, Jerry had tracked the Russian torpedoes, figuring out their course and the direction of their turn. He had to do it in his head, because the Manta’s displays were not designed to plot and track multiple contacts. Figuring a sixty-degree-wide search cone on the front of each weapon, he’d adjusted the Manta’s course to put it in front of the torpedoes, but not on a direct line drawn from the weapons to Memphis.
He dropped the last Mark 3 torpedo countermeasure and then headed off to the west, at right angles to the torpedoes’ course.
“Conn, sonar, sierra nine one is at speed now and we can hear his propulsion plant. Contact is classified as an Akula-class SSN, possibly an Akula II.”
Wonderful. One of their newest and best, Jerry thought, although any elderly hulk with torpedo tubes would be a problem right now.
He continued to feed ranges and bearings to the contacts up to
fire-control party in control and detected the Akula’s turn almost as soon as sonar reported it. “He’s turning and slowing.” For what purpose?
The torpedoes were indeed heading for Jerry’s countermeasure, and Jerry angled the Manta to the northwest at moderate speed to keep clear of their seeker cones. Memphis’ decoy had started to fade, while the Russian’s countermeasure continued to send out a storm of white noise.
The Russian sub was now almost due west of Memphis, heading north. Memphis was going northeasterly, while the Russian torpedoes circled and harried Jerry’s countermeasure behind her, to the south. Once the Russian countermeasure was abaft his port beam, Jerry changed course to due north and increased speed, trying to position himself between Memphis and the Akula.
But where to go next? Hardy wanted him to distract the Russian boat and Jerry realized that would be easy. He put the Manta on an intercept course and ordered it to go to maximum speed. He also turned on the simulator mode. Maybe the Russian would go nuts trying to figure out what an American nuke boat was doing with a forty-kilohertz sonar.
Jerry kept a wary eye on the torpedoes to the south, on the off chance that their seekers might pick up the Manta, but most of his attention was focused on the Akula. What would it do next and how could he screw around with their minds?
He’d kept control informed of his movements, and Hardy had ordered Memphis to slow to creep speed, hoping to disappear from the Russian’s passive sonar.
“Conn, sonar. Sierra nine one is turning to starboard.” Then the supervisor’s voice increased in pitch. “Launch transients! Torpedoes in the water, bearing two nine zero!”
The Manta’s passive display wasn’t as detailed as Memphis’ upgraded BQQ-5E and Jerry wasn’t as skilled as the sonarmen, but he could see the launch noises on his display and his imaging sonar actually saw one, then two torpedoes as they left the Akula. “Control, U-bay. I can see the weapons!” he announced. “Two torpedoes in the water! Bearing three one zero, range two five hundred yards.”
“I’ll wait on evading until you tell me where they’re headed,” Hardy said.
“Understood. Torpedoes showing zero bearing rate. Range, two two hundred yards from the Manta.” That put them on a course away from Memphis, which lay almost directly off the torpedoes’ port side. “Conn, sonar. Weapons are at search speed.” That was good. A typical torpedo searched at thirty or forty knots, then jumped to fifty or sixty to make an attack. The first pair had been fired at attack speed, so maybe the Russian captain wasn’t sure of his target and fired prematurely. At the combined speed of the torpedoes and the Manta, it would take the weapons one minute to cross the distance.
“Conn, sonar. Torpedoes are drawing to the right,” sonar announced.
Jerry answered, “Steady bearing on the Manta.”
Jerry kept feeding ranges and bearing to control, as well as trying to create a mental picture in his head. The Russian sub had slowed down and was heading southeast, toward him. Either the Akula thought he was Memphis or regarded him as a greater threat. Either conclusion suited Jerry just fine.
“They’re headed toward me,” Jerry announced after a thirty-second eternity.
“Concur. Get out of there,” Hardy ordered unnecessarily.
“Doing it,” Jerry acknowledged.
He turned sharply to the east and held that course for a few seconds. He wanted the Russian to see the course change. Then he dropped a decoy, one of the two large Mark 4s the Manta had left, chopped his speed, cut the simulator mode, and dove for the bottom. Hopefully, he’d just disappeared from the Russian passive displays.
Jerry then turned the Manta back northward, toward Memphis. It was too early to rendezvous with the sub, but he couldn’t let the distance grow too great. The last thing he needed right now was a large time lag in the Manta executing his commands. Memphis was now heading due north. The Russian had stopped turning and was closing on Jerry’s last known position, which was conveniently marked by a very loud countermeasure.
The Akula’s latest pair of weapons started to range-gate, switched to shorter interval search rate, and increased speed. They covered the last five hundred yards to the countermeasure at what looked like fifty knots. As they pinged, a sharp high-frequency spike appeared on Jerry’s display and so quickly vanished that it merely blinked. Jerry saw them reach the spot and continue onward, heading southeast for another few moments. The ping rate slowed, managing to sound almost plaintive, and the weapons started circling, returning to search speed. They had shifted to a reattack mode. Jerry quickly checked the distance and saw that he was well outside the seekers’ acquisition range.
He watched the Russian sub for any sort of reaction. It had shot at Memphis and she’d evaded. Their second attack had missed as well. Did they still have sonar contact on Memphis? Had Jerry done a good enough job of impersonating a nuclear submarine? The Akula could zig east and south toward Jerry’s old position, or north and east toward Memphis. If they had truly lost contact, then Jerry doubted the Russian would head north.
A new spike appeared on Jerry’s acoustic intercept receiver display, but way to the left, at the low-frequency edge. Almost at the same moment, Jerry heard, “Conn, sonar. Shark Gill transmission bearing two seven zero! Sierra nine one has gone active!”
The Russian captain was tired of being subtle. This wasn’t some pipsqueak little high-frequency set. The Akula’s Skat-3 sonar suite included three large powerful active arrays, one in the sail and one on either flank. It put out enough energy to kill a swimmer if he was near the sub and the low-frequency sound carried underwater for a long way.
“He’s got us,” announced Hardy as he looked at the intercept receiver. “Mr. Mitchell, get in between us and the Russian, max speed. Do whatever you have to do. I’m dumping another countermeasure.”
Jerry had to sandwich his response in between Hardy’s commands to sonar and the other stations. He turned on the simulator mode again and brought the Manta up to the same depth as the Russian sub. He also increased speed to twenty knots. With luck, he could get between the two subs and confuse or obstruct the Russian’s view.
He tried to visualize the Russian’s sonar display. Two echoes. He didn’t know if they looked the same on the Akula’s sonar display or not. One closing at twenty knots, one moving away at a slower speed. The latter had just launched a countermeasure that would show up on both active and passive sonar displays. Jerry told the Manta to eject a decoy, his last. One less difference between the two contacts. He was tempted to turn off the Manta’s active sonar, which the Russians could detect, but decided he needed the information.
Again, Jerry found himself straining to think of ways to attract the Russian’s attention, The Akula’s captain was desperately trying to sort out the situation, evaluating threats, preparing for his next attack, attempting to follow his orders.
The Akula fired again, another pair of weapons. Both Jerry and sonar called the launch to control; after a few seconds it was clear that Memphis was the target. This time, with an accurate fix from the Akula’s active sonar, Jerry knew the weapons would have a much better fire control solution.
He felt the deck shift below him as Memphis turned hard to starboard and dove deeper. Jerry also heard Ho’s protests as Hardy ordered every fractional knot of speed that was left in the plant, but his mind was inside the Russian sub. He imagined the captain sorting out the situation, deciding which of the two contacts represented his real target, and then firing.
So if Jerry couldn’t convince him that he was the real target, then he’d convince the Russian he was a greater threat. He was still on a course that took him between the two subs, but he wasn’t in position to decoy the torpedoes, and probably wouldn’t be until it was too late.
Instinctively, he turned toward the Akula, now about fifteen hundred yards away. He made sure that his speed was set to maximum, twenty knots. At this speed, he’d ram the Russian in about two minutes. Memphis was now headed directly away from the tor
pedoes, but her best speed was only twenty knots. She couldn’t outrun the weapons even at search speed. She could only prolong the chase.
“Conn, sonar. Torpedoes are range gating! They’re increasing speed!” The sonar supervisor was doing his best to keep his reports professional, but he knew better than most what was heading straight for Memphis.
Jerry called out the torpedoes’ location and also the remaining distance between him and the Akula. The torpedoes would definitely reach Memphis before he could reach the Akula.
“They’re ignoring the countermeasure!” Bair shouted. Then Hardy ordered, “Chief of the Watch, release another Mark 2 countermeasure!”
Then sonar reported, “Conn, sonar. Sierra nine one is zigging. He’s in a hard turn to port and he’s increasing speed. Radical maneuver!”
Jerry could see him on the active display and could tell that he was changing depth. He hadn’t dropped a countermeasure, so the Russian captain knew that Jerry wasn’t a torpedo, but he also knew they were about to collide. The Russian maneuvered to avoid getting hit.