Final Option (Oregon Files 14)

She played another audio clip. This one was fainter, and it took a moment for Jefferson to recognize it for a man-made sound. When she did, she looked at Harper with surprise.

“Am I crazy,” Jefferson said, “or is that the sound of a ship’s propeller?”

59

The extreme depth of the fjord they were navigating allowed the Chinese sub Wuzong to glide through the channel at one hundred feet below the surface, making it undetectable by any aircraft flying overhead. So far, they’d detected no ships.

Admiral Yu Jiang calmly watched the depth gauge and asked for constant updates from his sonar officer.

His executive officer, on the other hand, had been agitated ever since they had left the vast empty spaces of the open ocean.

“These underwater canyons are getting narrower the closer we get to the mainland,” the nervous XO said. “Perhaps we should have stayed at the entrance to the northern pass as Tate wanted us to.”

Yu sneered at him. “And simply wait for the Oregon to come to us?”

“Tate said that he would herd the ship in our direction. You would get the glory of sinking her.”

“Of course that’s what he would say. But he wants revenge just as much as I do. I could sense it in his voice. He will attack the Oregon the moment he sees her. He’s just using us to keep her from escaping.”

“The Wuzong was not meant to operate this close to shore.”

“Don’t you trust our country’s scientists?” Yu asked him.

“I do,” the XO said. “But we have never tested the new sonar system in real-world conditions.”

“Then consider this the test. Not only will we get our revenge, we will prove the viability of our experimental sonar and acquire a valuable new weapon when Tate hands over his designs for the sonic disruptor.”

Underwater, a submarine was virtually blind, relying on inertial navigation and existing maps for plotting its course. In the open ocean, where undersea obstacles were few and well documented, this type of navigation was sufficient. Passive sonar provided positional information on moving objects like ships and other subs.

But to see subsurface obstacles closer to shore required the use of active sonar, which sent out a powerful ping that reflected off of stationary objects. The echolocation provided a detailed image of the surrounding topography, but it also revealed the sub’s position and its proximity to any ships in the vicinity.

For that reason, military subs rarely ventured into shallow waters unless they were in friendly ports and had the benefit of seeing traditional navigational markers like buoys and lighthouses, while either on the surface or below, using the periscope.

But Chinese researchers had come up with a compromise that allowed their nation’s subs to venture into foreign waters without being detected. They had installed an active sonar on the Wuzong that simulated the call of the humpback whale.

The sonar signal was emitted at the same intensity as the song produced by an actual whale. This meant that its reflected signal was less powerful than that produced by a traditional sonar, so the sub had to move much more slowly than normal, like a car creeping through pitch-black night with weak headlights.

Any ships hearing the signal would simply think a whale pod was passing by, never suspecting that the song had been recorded from a whale in Hawaii. And since humpbacks ranged over the entire world, the sonar could be used anywhere without raising suspicions.

“Any ships in the area?” Yu asked the sonarman.

“No, sir,” the executive officer replied. “The only man-made object on my scope is that buoy we just passed.”

Yu knew that the Deepwater was conducting oceanographic research in the area. He suspected it was something boring, like the analysis of water temperature or tidal movements. His sub wouldn’t trip any of those types of sensors.

“Clearance?”

“One hundred meters from the bottom,” the sonarman said. “Three hundred meters on either side.”

Yu smiled at his XO. “You see? Plenty of room.”

The XO pointed at the map. “It will get narrower soon.”

“Then we will go even more slowly. We’re going to check every channel that the Oregon could fit into.”

“Certainly not this one, though.” The executive officer was pointing to a waterway that bent around on itself and dead-ended in a cul-de-sac. It was more than two miles long, and entering it would require a tight U-turn. One mile in, then another mile back to the end after the turn.

Yu nodded firmly. “Yes, that one, too. The end widens enough for us to make the turn to exit.”