Two hours before he had removed a torpedo from one of his tubes and replaced it with a Harpoon missile. It gave him only one torpedo ready for instant use if he found a submarine target, but a salvo of three missiles available to fling at surface ships, plus his Tomahawks. He could fire either now, and expect hits, but McCafferty didn't want to fire at just anything. There was no sense wasting a missile on a small patrol craft when there was a cruiser and a carrier out there waiting for him. He wanted to identify specific targets first. It wouldn't be easy, but he knew that easy things didn't have to be done by the 688-class subs. He went forward into sonar.
The chief caught him out the comer of his eye. "Skipper, I may have a bearing to Kirov. I just copied six pings from a low-frequency sonar. I think that's him, bearing zero-three-nine. Trying to isolate his engine signature now. And if-okay, some more sonobuoys are dropping to the right." The display showed new points of light well to the right of the first string, and a sizable gap between the two.
"Think he's dropping them in chevrons, Chief?" McCafferty asked. He got a smile and a nod for an answer. If the Soviets were deploying their sonobuoys in angled lines left and right of the formation, that could mean that their ships were heading right for Chicago. The submarine would not have to maneuver at all to intercept them. She could stay as quiet as an open grave.
"They seem to be alternating them above and below the layer, sir. A pretty fair gap between them, too." The chief lit a cigarette without averting his eyes from the screen. The ashtray next to him was crammed with butts.
"We'll plot that one out. Good work, Barney." The captain patted his sonar chief on the shoulder and went back to the attack center. The firecontrol tracking party was already plotting the new contacts. It looked like an interval of just over two miles between the sonobuoys. If the Soviets were alternating them above and below the layer, there was a good chance he could sneak between a pair. The other question was the presence of passive buoys, whose presence he could not detect.
McCafferty stood at the periscope pedestal, watching his men at work as they entered data into the fire-control computers, backed up by other men with paper plots and hand-held calculators. The weapons-control panel was lit up by indicators showing ready. The submarine was at battle stations.
"Take her up to two hundred feet, we'll listen above the layer for a few minutes." The maneuver paid off at once.
"I got direct-path to the targets," the sonar chief announced. They could now detect and track sound energy radiating directly from the Soviet ships, without depending on the on-again, off-again convergence zones.
McCafferty commanded himself to relax. He'd soon have work enough.
"Captain, we're about due for another sonobuoy drop. They've been averaging about every fifteen minutes, and this one might be close."
"Getting that Horse-Jaw sonar again, sir," sonar warned. "Bearing three-two-zero at this time. Signal weak. Classify this contact as the cruiser Kirov. Stand by-another one. We have a medium frequency active sonar bearing three-three-one, maneuvering left-to-right. We classify this contact as a Kresta-II ASW cruiser."
"I think he's right," the plotting officer said. "Bearing three-two-zero is close to our bearings for a pair of screen ships, but far enough off that it's probably a different contact. Three-three-one is consistent with the center screen ship. It figures. The Kresta will be the screen commander, with the flagship a ways behind him. Need some time to work out the ranges, though."
The captain ordered his submarine to stay above the layer, able to duck beneath it in seconds. The tactical display was evolving now. He had a workable bearing on Kirov. Almost good enough to shoot on, though he still needed range data. There seemed to be a pair of escorts between him and the cruiser, and unless he had a proper range estimate, any missile he launched at the Soviet flagship might attack a destroyer or frigate by mistake. In the interim, the solution on the attack director set the Harpoons to fly straight for what he believed to be the battle cruiser Kirov.
Chicago began to zigzag left and right of her course track. As the submarine changed her position, the bearing to her sonar contacts changed also. The tracking party could use the submarine's own course deviation as a baseline to compute ranges to the various contacts. A straightforward process-essentially an exercise in high-school trigonometry-it nevertheless took time because they had to estimate the speed and course of the moving targets. Even computer support couldn't make the process go much faster, and one of his quartermasters took great pride in his ability to use a circular slide rule and race the computer to a hard solution.
The tension seemed to grow by degrees, then it plateaued. The years of training were paying off. Data was handled, plotted, and acted upon in seconds. The crew suddenly seemed a physical part of the gear they were operating, their feelings shut off, their emotions submerged, only the sweat on their foreheads betraying that they were men after all, and not machines. They depended absolutely on their sonar operators. Sound energy was their only indication of what was happening, and each new bearing report triggered furious activity. It was clear that their targets were zigzagging, which made the range computations even more difficult.
"Conn, sonar! Active sonobuoy close aboard to port! Below the layer, I think."
"Right full rudder, all ahead two-thirds," the executive officer ordered instantly.
McCafferty went to sonar and plugged in a set of headphones. The pings were loud but... distorted, he thought. If the buoy was below the temperature gradient, the signals radiating upward would be unable to detect his submarine-probably. "Signal strength?" he asked.
"Strong," the chief replied. "Even money they might have picked us up. Five hundred yards farther out and they lose us for sure."
"Okay, they can't monitor them all at once."
The XO moved Chicago a thousand yards before returning to base course. Overhead, they knew, was a Bear-F ASW aircraft armed with homing torpedoes and a crew whose job it was to listen to the sonobuoy signals. How good were the buoys and the men? That was one thing that they didn't know. Three tense minutes passed and nothing happened.
"All ahead one-third, come left to three-two-one," the executive officer ordered. They were now through the line of buoys. Three more such lines were between them and their target. They'd nearly determined range for three of the escorts, but not to the Kirov yet.
"Okay, people, the Bears are behind us. That's one less thing to worry about. Range to the nearest ship?" he asked the approach officer.
"Twenty-six thousand yards. We think he's a Sovremenny. The Kresta is about five thousand yards east of him. He's pinging away with hull and VDS sonars." McCafferty nodded. The variable-depth sonar would be below the layer and had scant chance of detecting them. The hull sonar they'd have to pay attention to, but it wouldn't be a problem for a while yet. Okay, the captain thought, things are going pretty much according to the plan-
"Conn, sonar, torpedoes in the water, bearing three-two-zero! Signal faint. Say again torpedoes in the water, three-two-zero, bearing changing --additional, lots of active sonars just lit up. We're getting increased screw noises for all contacts." McCafferty was in the sonar room before the report ended.
"Torpedo bearing change?"
"Yes! Moving left-to-right-Jesus, I think somebody's attacking the Russians. Impact!" The chief jabbed his finger at the display. A series of three bright spokes appeared right on the bearing to Kirov. The display suddenly went berserk. The high-and medium-frequency segment lit up with active sonar lines. The lines indicating ships became brighter as the ships increased engine speeds and changed direction as they began to maneuver.