That still left a lot of room for them to be very, very good.
“350 relative! Range 3500 meters and closing!”
It was eerie, having his prediction fulfilled like that. He had tossed it off, based, yes, on some experience. But mostly to steady the bridge crew. The bastard was coming around toward them, and quite fast, now that his engines were driving him again.
“Take us down to 255 meters, bow up.”
“255 meters, bow up, aye.” The Admiral Po began a very slow dive, aiming to get her metal bulk through the deep isothermic layer that would reflect most sonar and greatly hamper passive detection. The captain looked down at his knuckles on the collision bar in front of his command seat and gradually willed his hands to relax.
In the darkened ballroom, there are long, velvet curtains that hide sound if you can get behind them.
“000 relative, 3000 meters and closing. Speed five knots. Vector 190.”
The boomer suddenly appeared as a digital symbol on the command screen with her course and speed displayed next to her. The distance between the Admiral Po and her quarry seemed very short, and the captain wondered if they were about to change roles.
“255 meters.”
“Try to put the bow sonar up in the layer.”
“Bow up, aye.”
This was a tricky maneuver and one that couldn’t really be accurately gauged for success. It required that the planesman adjust the pitch of the submarine so that her bow sonar was actually above the acoustic layer, allowing that sonar to listen to the enemy while the rest of the submarine’s metal hide was hidden below the temperature gradient of the layer. The problem was that you never knew for sure that you had it exactly right; the acoustic layer was simply a metaphor for the invisible line where two different layers of water with different temperatures met. It couldn’t be seen, only sensed, and only sensed as a relative gradient. The bow might be in the layer or meters above it, depending on luck and skill and local variations.
He’s bow on to us right now. The American, with his infinitely superior equipment, was in the best position he could ask to detect Admiral Po.
“Nothing on the tail.”
“Bow sonar has contact, 010 relative, 2500 meters and closing. Speed five knots. Vector 180.”
He has us. Or he will turn away.
The captain turned to the planesman.
“Well done. Very well done.” The bow sonar report indicated that the bow was, indeed, above the layer. But how far? And how reflective was the layer?
He watched the symbol on the bridge screen, the only visual input that mattered, willing it to continue its turn to port.
“020 relative, 2700 meters. Speed six knots. Vector 160.”
Deep breath, long exhalation.
“Make revolutions for three knots. Hold us at 255 meters and pitch for normal.”
“Aye, aye.” That pulled the bow back under the layer, making them blind, but he had to move or the American would get too far away. Simply avoiding detection was only half the game.
“Three knots.”
“Helmsman, three knots for the center of the channel.”
“Aye, aye.”
He cast an eye at the chart and decided he had a safe amount of water under his keel, even in these treacherous seas.
“Depthfinder off.”
“Depthfinder off, aye.”
Ahead, perhaps well ahead if he stuck to his six knots, the American would be entering the channel already. The captain calculated quickly; the American would be well over six thousand meters ahead when they were back in the deep water on the other side of the channel, but the captain thought that the risk was worthwhile, and he was a little distracted by the obvious adulation of the bridge crew and his own internal buzz of triumph. He had outguessed an American boomer captain. His crew had reacted well. He was worthy.
“Center of the channel.”
He waited patiently, following the channel on his chart while thinking over the last set of moves, trying to guess the next. His eyes actually closed twice. Minutes trickled by. He hated letting the American have so much time undetected, but he couldn’t risk anything in the narrow channel.
“Bow sonar has possible contact, range seven thousand meters, bearing 000 relative.”
He snapped fully awake.
“Speed?”
The man looked anguished. The data were too sketchy. He needed a longer hit, or a second and third hit in quick succession to get a vector and speed.
Seven thousand meters was too far ahead, and too far for the bow sonar to make contact. Unless he was going very fast. It had to be a false contact—a seamount, or a boat. Or another submarine. He struggled with the possibilities as his own boat continued to creep down the channel.
“All engines stop. Planesman, bow above the layer.”
The Admiral Po seemed to hold its breath.
“Possible contact, range seven thousand meters, bearing 000 relative.”
The image returned on the command screen.
“Vector 000. Speed twelve knots.”
The American was racing away. He would be clear of the channel in moments; indeed, given the vagaries of passive sonar, he might be free now, and increasing speed.
“Make revolutions for four knots. Retrieve the tail.” It was useless in the channel, anyway. The American was surely too far away to hear its telltale 44dB line as the bad bearing in the towed array winch screamed.
Were they detected? He didn’t think so, couldn’t think so. This had the smell of a standard operating procedure, a routine to lose hypothetical pursuit. If so, it was crushingly effective.
“Towed array housed, sir.”
“Very well. Make revolutions for six knots.”
At six knots, the Admiral Po was one of the loudest leviathans in the deep. Her second-generation reactor could not be made really quiet by the addition (and in some cases the slipshod addition) of the best Russian quieting materials from the third generation—isolation mounts, for instance. The captain hated to go above four knots in an operational patrol. He felt naked.
They roared along the channel, a painful compromise, too loud to avoid detection, too slow to catch the American if he was determined to go fast.
“How did we miss him going so fast? I make no accusation, understand. I need to know.”
“Captain, he is not much noisier at twelve knots than at six. Even the cavitation noise is, well, muffled. He is very quiet.”
No submarine should be so quiet at twelve knots.
In Severomorsk, they had told him