Lieutenant Vaugh, seated at the command workstation as Junior Officer of the Deck, examined the time-bearing plot on his display. After noting the bearings to Master One were drifting left, he announced, “Confirm target zig, Master One. Set anchor range five thousand yards. Contact has turned to port and is on a closing trajectory.”
A moment later, the Sonar Supervisor reported, “Receiving high-frequency ice-detection pulses from Master One.”
Dolgoruky was definitely headed toward them.
“Steady on course one-eight-zero,” the Steersman announced.
Stepanov acknowledged the report, then checked the geographic display on the fire control console. He had turned with a ten-degree rudder, putting Dolgoruky on a reciprocal course with a slow turn to the west. The last thing he wanted was to run into a submarine trailing them. The water column was very narrow, with only 140 meters between the ocean bottom and the lowest ice keels. After taking into account safety margins to the bottom and ice above, Stepanov figured both submarines were traveling at the same depth or close to it.
It would not be long before they would learn if the American submarine was still following them. He waited for a report from Hydroacoustic, but the Command Post speakers were silent. Another minute passed without a report, then a voice broke the silence.
“Command Post, Hydroacoustic. Hold a new contact on the towed array, designated Hydroacoustic seven, a sixty-point-two-Hertz tonal, ambiguous bearings one-six-zero and two-zero-zero.”
Stepanov responded immediately — they were approaching the sixty-meter-deep ice ridge.
“Prepare to Fire, tube One.”
His crew executed the order quickly, and in less than a minute, Stepanov received the report from Captain Lieutenant Evanoff. “Ready to fire, tube One.”
“Launch decoy, tube One.”
The fire control Michman announced, “Decoy launched from tube One.”
Stepanov ordered, “All stop. Shift to electric drive.” He glanced at the under-ice sonar. The ice keel was five hundred meters away. Stepanov followed up with, “Secure all sonars.”
The watchstanders complied and the Steersman soon announced, “Propulsion has been shifted to the electric drive.”
Dolgoruky had gone quiet, securing its main engines and sonars. There was one thing left to do. “Steersman, back one-third. Compensation Officer, set Hovering to fifty meters.”
Dolgoruky slowed, rising toward the ice.
“Conn, Sonar. Picking up transients from Master One.”
“What kind of transients?” the Navigator asked.
The Sonar Supervisor answered, “We detected a faint broadband transient, which lasted for ten seconds. It wasn’t metallic — it sounded more like cavitation. But there’s been no change in Master One’s frequency that would correlate to a speed increase.”
As Tolbert tried to figure out what Dolgoruky was up to, he examined the sonar screens. Dolgoruky’s fifty-Hertz tonal was coming in stronger than ever now that Dolgoruky had turned toward them and was closing. How close would she get? He examined the geographic plot on Petty Officer Phillips’s display. Dolgoruky was headed south at ten knots, with a CPA of two thousand yards.
Tolbert had a problem. At two thousand yards, North Dakota would likely be detected. But to open CPA range, he’d have to turn away, no longer following in Dolgoruky’s track. There was no way he was going to travel blindly under the ice cap, yet at the same time, he didn’t want to activate his under-ice sonar, giving away North Dakota’s presence.
That was his dilemma. Activate his under-ice sonar and ensure counter-detection, or let Dolgoruky close to two thousand yards and hope for the best. Neither was a good option, but he chose the lesser of two evils. He would stay on course.
However, he could improve the odds North Dakota passed by undetected. “Pilot, all stop.”
North Dakota’s main engine turbines, reduction gears, and propulsor stopped spinning. Slowly, North Dakota coasted to a halt.
As Dolgoruky rose slowly toward the ice canopy, Stepanov monitored his submarine’s depth and speed. They had risen to ninety meters, approaching zero knots.
“Steersman, all stop.”
The sixty-meter-deep ice keel would soon be between Dolgoruky and the American submarine. For Stepanov’s plan to work, the American submarine had to stay on the other side of the keel, and that depended on whether Dolgoruky’s decoy fooled them.
As Dolgoruky rose to seventy meters, the Hydroacoustic Party Leader made the report Stepanov hoped for. “Command Post, Hydroacoustic. Ten knot downshift in frequency from Hydroacoustic seven. Contact is slowing or turning away.”
The American submarine had either stopped or turned ninety degrees. When the decoy passed by, the American captain would hopefully turn and follow, staying on the other side of the ice keel.
The Steersman called out, “Depth, sixty meters, zero knots.” Dolgoruky’s ascent slowed, and a moment later, Stepanov received another welcome report. “Command Post, Hydroacoustic. Loss of Hydroacoustic seven.”
The ice keel was now between the two submarines, and if Dolgoruky could no longer track the American submarine, the Americans could not detect Dolgoruky.
“On ordered depth, fifty meters,” the Steersman announced.
Dolgoruky hung motionless beneath the ice.
Tolbert watched tensely as Master One approached its CPA of two thousand yards. As the contact closed, Sonar reported a detection of Master One on the spherical array and then the port Wide Aperture Array on North Dakota’s hull. It was quiet in the Control Room. Every watchstander realized how close the Russian submarine would come.
The contact’s course and speed remained steady as it reached CPA, then passed by. When Master One opened to four thousand yards, Tolbert resumed trailing. “Pilot, ahead two-thirds. Left five degrees rudder. Steady course one-eight-zero.”
North Dakota picked up speed and reversed course, and a few minutes later settled back into Dolgoruky’s wake. Master One remained steady on course and speed, giving no indication North Dakota had been detected.
As the tension eased from Tolbert’s body, the Sonar Supervisor spoke into his headset. “Conn, Sonar. Request the Captain at Sonar.”
Tolbert joined Chief Bob Bush on the port side of Control.
“We may have an issue,” Bush began. “Master One passed by at two thousand yards, but we didn’t pick up propulsion or steam-plant-related broadband. Additionally, we should have picked up other tonals, but we didn’t. We held only the fifty-Hertz tonal and Dolgoruky’s ice-detection sonar.”
Tolbert considered Chief Bush’s report. The contact was too clean. Nuclear-powered submarines had dozens of pumps, electrical generators, and spinning turbines creating noise. At long distances, only strong, low-frequency tonals were detected. But as the range decreased, higher-frequency tonals as well as broadband would normally be heard. Either Dolgoruky was an incredibly quiet contact, or …