SSN

    Captain Mackey was, as were all experienced submariners, at least slightly familiar with the Han class of submarine. In addition, when word was passed of a possible war with China, the intelligence officer assigned to SubRon 11 from SubGroup 5 had quickly prepared a brief report of what was known of the Han class in the U.S. intelligence community. According to that report, construction of the Han class had stopped after only five submarines due to extremely high internal radiation levels, and all of those were currently in service with the Chinese navy. They carried the pennant numbers 401, 402, 403, 404, and 405 painted on their sail. One of the class had, of course, been destroyed earlier that month by a U.S. SSN. Naval intelligence was still unsure which number it was, but they reported that it was probably number 402, the second of the class. They were assuming this because it had been tracked since leaving Ningbo Naval Base in China's East Sea Fleet four days prior to the actions involving Nimitz.

    The torpedo complement fitted to the Han class was reported to be a mix of the older straight-running types as well as some of the newer Russian homing varieties. According to the reports, numbers 401 and 402 carried only torpedoes, but the last three submarines of the class, numbers 403 to 405, carried the Ying Ji. Also known as the Eagle Strike, this antishipping missile was a sea skimmer and caused great concern in the eyes of naval commanders. The most recent intelligence reports stated that while these missiles could be a significant threat to warships, the submarine needed to surface in order to launch them. And submarine commanders knew all too well that a surfaced submarine was an easy target.

    Unlike the USS Seawolf, Cheyenne did not have a wide aperture array, or WAA, so she would have to triangulate the position of her passive sonar contacts in order to determine their exact bearing, speed, and range. The ship maneuvers to accomplish this would have to be done very quietly, especially if the contact, TKVW designated Master 1, was a direct-path contact. But it was a painfully slow process.

    "Captain," the sonar supervisor said, "it's possible the submarine was tracking us but lost us when we slowed. With these convergence zones out here in deep water, it could be in excess of 75,000 yards away. My guess is that he thinks we passed him, and based on its blade rate, is running full speed in an attempt to catch up with us and regain contact."

    That was a good guess, Mack thought, but it was still just a guess. He wanted something more than that. Proceeding to the conn, he ordered the OOD to station the section fire-control tracking party so the BSY-1 computers could be used to determine the solution on the target. The OOD would maneuver the submarine in order to change the bearings received by the towed arrays.

    Mack also ordered the OOD to house the TB-16 towed array and deploy the TB-23 towed-array. Unlike the 240 feet of TB-16 hydrophones, the TB-23 towed-array sonar measured over 900 feet in length, mounted nearly 100 hydrophones, and was towed at the end of a 2,600-foot cable. Then he returned to the sonar room.

    "Captain, blade rate indicates Master 1's speed is steady at eighteen knots," reported the sonar supervisor. "We're getting more tonals now, including one from the conformal array. She's definitely not American. The tonals compare to those listed in the sonar intelligence manuals as unique to Chinese Han class, number 402."

    That stopped Mack. "I thought 402 was sunk by the submarine escorting Nimitz" he said.

    "So did naval intelligence," the sonar supervisor replied. "I guess they got their numbers mixed up. Wouldn't be the first time."

    The captain called to the OOD, "Begin retrieving the TB-23.1 don't want to get tangled up in case we have a fight on our hands." The towed-array sonar was valuable for quietly listening to passive sonar contacts, but Mack, like many submarine captains, preferred to retrieve it before engaging in close combat with an enemy submarine.

    Mack left the sonar room and went back to the conn to see how the fire-control solution was coming.

    "Conn, sonar, our contact, Master 1, just stopped his shaft."

    Seven more minutes passed, Cheyenne''s sonar operators carefully monitoring the tonals from the Chinese submarine's reactor coolant pumps. These had to be run constantly in order to avoid destroying the reactor, one of the few drawbacks of a nuclear-powered submarine. A conventional, or non-nuclear, submarine could stop dead in the water, running entirely on her battery power, and be completely silent. A nuclear submarine, however, such as Cheyenne or Han number 402, had to constantly pump reactor coolant in order to keep the reactor critical and prevent its overheating. That difference meant that it sometimes could be easier to hunt an SSN than a regular diesel boat-especially when the SSN was an old, 1970s-vintage Han with reactor plant problems.