Techniques and technologies were much improved nowadays. Torpedoes carried their own active sonar, allowing them to lock onto the target submarine and follow it.
Modern countermeasures were devices dropped from special launchers amidships and allowed to drift into a submarine's wake, generating a cloud of bubbles… and noise. That noise could mask the propeller noise of the sub, and confuse the people steering a wire-guided torpedo. And for an actively homing fish like this one, it could block and scatter the torpedo's homing pings, causing it to lose its target momentarily.
The key word was "momentarily." As soon as the torpedo punched through the bubbles, it would begin searching for a target once again, and was usually programmed to circle the area until it reacquired.
"Three-zero-zero yards! Seventeen seconds to impact!"
Eyes still closed, Gordon continued to visualize the encounter, the torpedo less than three boat lengths astern. If that seventy-kilogram warhead detonated on or near Pittsburgh's cruciform tail, her screw would be destroyed, and her rudder and stern planes. She would have to blow ballast and surface, then wallow helplessly until Soviet surface vessels arrived to take her in tow. If she flooded and went down instead, she would end up resting in less than two hundred feet of water, an easy recovery operation for the Russians.
"Fifteen seconds to impact! Fourteen… "
"Release countermeasures!"
"Twelve …"
"Countermeasures away, sir!"
"Maneuvering! Give me everything you've got!"
He kept visualizing, counting silently to himself. He needed to allow time for Pittsburgh's length to slide all the way through the bubbles now exploding up and out… a cloud hanging in place while the submarine continued to move forward at just over thirty-five knots.
"Ten!.. Nine!.. "
"Helm! Hard left rudder! Now!"
"Hard left rudder, aye, sir!"
"Seven!.. Six!.. "
The deck tilted sharply beneath Gordon's feet, and he reached out to cling to one of the periscope housings. This was as bad as angles and dangles; Pittsburgh was literally heeling far over onto her port side as she made the turn. There was a sharp clatter and crash as someone's coffee cup skittered off a surface and smashed on the deck. A deeper, hollow sound, a groan of stressed metal, echoed from above the control room.
"Conn, Maneuvering! We're at one hundred fifteen percent on the reactor! Making turns for three-eight knots!"
"Conn, aye. Helm! Maintain hard left rudder! All hands! Brace for collision!"
"Three!.. Two!.. One!.. "
Gordon looked up toward the overhead, waiting. "Plus one!" Rodriguez announced. "Plus two! Sir! He missed!"
"Keep on it, Sonar! Tell me which way it circles!"
"Sonar, aye! But it's getting hard to hear anything out there!"
The torpedo had punched through the cloud of bubbles, emerging to find the target looming just ahead of it… gone. Its computer brain would have a simple search pattern loaded aboard… a circle to either left or right, and possibly a change of depth as well, though in these shallow waters that probably wasn't necessary and could be ignored.
"COB. What are the stats on a Russian 406?"
Warren didn't even need to access the boat's warbook. "It'll be either an M1962 or an M1981."
"Assume the worst."
"M1981. Seventy-kilogram warhead. Maximum effective range six nautical miles. Top speed about thirty knots."
"That's what I thought." He'd been surprised by the torpedo's speed, but hadn't had time to think about it. Soviet 406mm ASW torpedoes were too small to mount the big and complex Stored Chemical Energy Propulsion System — SCEPS — of an American Mark 46, a pump-jet system that gave it a top speed of over fifty knots. They were powered by batteries, which made them slow and short-ranged for most ASW situations.
This fish was moving at better than twice an M1981's speed. The question was… what kind of propulsion system did it have, and had there been a trade-off in range? The older Soviet M1962s could travel three nautical miles before running out of juice, an M1981 about six.
That fish out there could burn through the water at twice the speed of earlier 406s, but you couldn't get something for nothing. There had to be a trade-off somehow … in speed, performance, or payload. Which was it?
"Conn! Sonar! I think we have aspect change on target! Torpedo turning to starboard!"
Gordon allowed himself a small, inner sag of relief. The torpedo could have gone left or right, port or starboard, the tossing of a coin. Had it turned port, in the same direction as the Pittsburgh, its higher speed would have taken it in a much larger circle, bringing it back around on a new heading, directly toward the 'Burghs bow. To counter, he would have had to turn inside the torpedo's turning radius, which would have put it on the Pittsburgh's tail once again.
If it was turning to port, however, it would describe the same big circle, but clockwise instead of counterclockwise… and since Pittsburgh was already heading away from it at almost forty knots, by the time it reacquired—if it reacquired — the American sub would have a tremendous lead.
"Conn, Sonar! We're cavitating!"
"Understood, Sonar." Pittsburgh was traveling so swiftly that vacuum bubbles were momentarily forming on the surface of the rapidly spinning screw, then collapsing, creating a characteristic sound that could be easily heard by others. Even without the cavitation, Pittsburgh was putting out a lot of noise as she raced north through the water, so much noise, in fact, that her own sonar was almost deaf. Rodriguez had been able to track the torpedo, thank God, because it was close and loud, but he wouldn't be able to hear much of anything else.
But he wanted to put as much distance between Pittsburgh and that 406 as he possibly could.
Minutes passed, as the Pittsburgh continued to race toward the north.
"Conn, Sonar. Sorry, sir, but we're deaf as a post in here. I lost the torpedo."
"Not to worry, Sonar," Gordon replied. "Keep listening in case it gets close again."
"Aye aye, sir. But at this speed, and with it coming up our baffles, it'll be point-blank before we can pick it up."
"Understood. Stay on it."
"Aye aye, sir."
Latham caught his eye. "You like giving impossible orders, don't you, Captain?"
"Not impossible, Number One. Just improbable. And nothing this crew can't handle." He said it deliberately and loudly. By the beginning of the next watch, the enlisted personnel in the control room would have spread his words throughout the boat, a far more effective form of praise, in Gordon's opinion, than some sort of pat, "well-done-men" speech.
He checked the big clock on the forward bulkhead. The torpedo had been in the water six minutes now … long enough to have covered over six miles. Unless the Russians had developed some sort of super high-tech wonder-motor, chances were the 406's batteries were exhausted by now, and the fish was floating on the surface.
He ordered Pittsburgh's speed brought back down to thirty knots, but held it there for another five minutes, just to be sure. By that time, they were well across the twelve-mile line and out into what were technically international waters.
Then he ordered the speed cut yet again, this time to a near-silent eight knots, and after a few minutes more, he ordered the Pittsburgh to be brought onto a new heading… of zero-one-five. That would take them past Mys Yelizavety, the northernmost cape of Sakhalin, fifty miles distant, and get them clear of this damned tight, shallow bowl.