More smoke appeared over Jake’s head and billowed into the vents behind the stacked monitors.
“Go on, Jake,” Renard said. “You cross an acoustic layer, it’s a whole new world. That drone can dive far deeper than we can. Send it deep.”
“You seem to be taking a lot of interest in this so-called shell of a torpedo,” Jake said.
“With time running short, I’m open to its possibilities now,” Renard said. “Maybe I’m no longer stuck in the fucking past, as you say.”
Jake heard Zhu’s fingers rapping against his keyboard with methodical precision, spiraling the drone downward with patience and dexterity. On his monitor, he watched the drone settle deep.
Zhu rattled off a comment that Ye translated.
“We’ve reached the limit of the guidance wire,” Ye said. “The drone is at maximum depth and distance.”
Jake stood and shouted across the Hai Lang’s operations room.
“Pierre,” Jake said, “it’s probably a good time for another bathythermograph. It might tell us how well this drone is placed.”
Renard had been engaged in conversation over Remy’s shoulder. He looked up and whispered to the Taiwanese petty officer seated beside Remy.
Jake was unsure if Renard had heard him until a temperature gradient unfolded on his monitor. The converging and diverging lines representing the sound channels reached into the depths as a newly expended bathythermograph descended below the Hai Lang.
Jake liked what he saw.
“Maybe some weather’s moving in,” he said, “or there’s a tidal effect. Whatever it is, the sound channels have changed.”
“The drone is at the bottom of the shallow channels and near the top of the deeper channels,” Ye said.
“Depending how accurate this model is, that means we might hear in both channels, or we might not hear anything. Let’s give it a chance to listen full circle,” Jake said.
The monitor showed the drone crawling through another tight search circle, and Jake listened as it carved its path through the depths. The drone’s acoustic input showed nothing of interest. Jake looked to Remy.
“Don’t ask,” Remy said. “I was already listening. Just more whale food and volcanic rumbling.”
“Take it active again,” Jake said. “All you got.”
Zhu tapped the keyboard and a wall of sound walked up Jake’s monitor. Nothing. Two twenty-degree turns later, Jake nearly leapt out of his chair.
“You see that?” he asked.
“Yes,” Ye said. “All of it.”
Like ghosts, four fuzzy masses appeared on the monitor. Jake stood to tell Renard what he saw, but a white cuff passed in front of his face as Renard pointed at the electronic specters.
“Four traces?” Renard asked. “That’s too many submarines — inconceivable.”
“Two pairs of traces,” Jake said. “One pair on each bearing, each bearing including a shallow direct-path acoustic return and a deep bottom-bounce acoustic return.”
“Two submarines, each heard twice,” Renard said.
Jake interrupted as Ye translated for Zhu.
“Is that drone capable of determining angle of elevation?” he asked.
“No,” Ye said. “Just a two-dimensional bearing.”
“That’s what I was afraid of.”
Jake tapped his keyboard and a monitor revealed a two-dimensional view. The Hai Lang, a blue inverted triangle, was at the center, the entrance to Pearl Harbor was to the northeast, and four red inverted triangles appeared to the southwest. The drone’s inverted blue triangle lay at the screen’s top.
“We know the range from the drone to each of the four contacts,” he said. “What we don’t know is which two contacts are acoustic phantoms, and which of the other two is the Hamza.”
“An excellent summary,” Renard said. “The other submarine is probably an American vessel observing the Hamza. Sadly, they are too uncertain of its intent to violate their rules of engagement and to destroy it in international waters.”
“That’s what we’re here for,” Jake said. “Now all we have to do is wiggle that drone in a little closer and—”
“Helm, all ahead standard,” Renard said.
Henri, seated forward of Jake at the ship’s control panel, raised his eyebrow but said nothing.
“Well, my friend,” Renard said. “You heard me.”
Henri turned and maneuvered a joystick. A line extended from the Hai Lang triangle on Jake’s monitor to indicate the forward motion.
“Standard?” Jake asked. “We have total tactical control. Don’t barrel in there like a bull in a china shop. All we have to do is sneak the drone in there, but if you go to ahead standard they might hear us.”
“I’m sorry, but we have no choice,” Renard said.
Jake didn’t understand but watched as Renard stepped up to Remy, nudged the sonar operator aside, and pressed a button at the monitor.
“You’ve been quite busy, Jake,” Renard said, “and I didn’t want to distract you. Take a look.”
Jake glanced at a bright blue square as it materialized on his monitor.
“We’ve been tracking the Stennis on its final approach to the harbor,” Renard said. “Our time is up.”
CHAPTER 33
A creature of habit, Commander Rodriguez studied the raw acoustic data. A physics major from the University of Virginia, he enjoyed the dynamics. He watched a fuzzy trace careen like a waterfall down a screen that showed azimuth direction in three hundred and sixty degrees.
Flipping through similar screens, he noticed that changing the depression or elevation angle hardly altered the intensity of the signal. The chaotic multi-frequency broadband flow noise of the aircraft carrier Stennis pushing the seas out of its way filled the Hawaii’s hydrophones from sail to keel.
Rodriquez flipped to a new view that showed sounds reaching the Hawaii in a discrete frequency band correlating to the revolutions per minute of the Stennis’ propeller blades. Through Doppler effect, the blades rotating towards the Hawaii arrived at a higher frequency than the blades that were rotating away.
Too much detail, he thought. Keep the big picture in sight. Let the sonar team verify this.
“Chief Bartlett,” he said. “How’s blade rate?”
The portly man in the blue cotton jump suit seated in front of him replied over his shoulder.
“Correlates to ten knots, sir.”
“Thanks, chief,” Rodriguez said.
He looked to the row of men seated at monitors running along the length of the Hawaii’s control room. Anticipating his next question, the Hawaii’s solitary navigation watch stander volunteered the answer.
“Ten knots was what harbor authorities told the Stennis to make, sir,” he said.
Rodriguez acknowledged the report and turned his attention to the screen below him. He flipped to an overhead, two-dimensional view that showed the blue square of the Stennis. An inverted red triangle represented the nearby Agosta class submarine.
He thought about asking a watch stander to calculate data but reconsidered. The automation in the Virginia class submarine made tapping his console easier than explaining himself and having someone else do it.
He tapped an icon on his console, and lines between the Stennis and the Agosta formed. The shortest of the lines — the closest point of approach between the two ships — was fourteen nautical miles.