and muttered to herself, “Boys will be boys.”
15. Cold Welcome
The next morning Jerry had the six to twelve watch in control. He and Tom Holtzmann arrived punctually at 0545, after their pre-watch tour through the boat, to begin the turnover with Lenny Berg. The relieving process always took some time, so officers were expected to show up at least fifteen minutes before their appointed watch.
Unlike the surface navy, which had four-hour watches followed by eight hours off, the submarine force used a more abusive six hours on, twelve hours off watch rotation. After six straight hours on watch, the brain turns to Tapioca pudding and all one wants is to be relieved on time. Usually, Jerry was paired with another officer who was the same rank or senior to him. But due to his aggressive qualification schedule, Jerry sometimes found himself standing watch with Ensign Holtzmann. Although Tom was junior to him in rank, he had more experience, and was formally qualified to be an OOD.
This meant he controlled the sub’s movements and actions during routine operations, and was responsible for three-quarters of a billion dollars of taxpayers’ money and the 137 souls aboard. If the boat went to General Quarters or some other special evolution, then the Captain would take over. Even if the Captain walked into the control room, Holtzmann would continue to run things, as long as Hardy was satisfied that he was doing a good job.
As the Junior Officer of the Deck, Jerry was learning on the job, backing up his book studies with on-watch time and training under a qualified officer. Eventually, he’d go before a board of
There was no Junior OOD on the earlier midnight to six watch, so Jerry listened as Tom relieved a very sleepy Lenny Berg. Lenny showed Holtzmann their progress on the chart, reviewed the status of the ship’s reactor and engineering plant, and warned him about anything coming up in the next six hours. Some of the information was repetitive, as they had just talked to the offgoing Engineer Officer of the Watch, but a little redundancy is preferred over ignorance. After a few brief questions, Tom relieved Lenny and announced the turnover formally to the new watch section.
Fifteen minutes into what Jerry had expected to be a quiet transit watch, the loudspeaker announced. “Conn, sonar. New contact bearing three zero zero. Designate new contact sierra seven six.”
“Sonar, conn aye,” replied Holtzmann as he and Jerry clustered around the sonar console in control. The console had only a single display, but it could repeat whatever was on the eight displays the sonarmen were looking at.
“Look,” said Tom Holtzmann. “Can you see what it is?” He stepped to one side.
Jerry studied the computer screen, called a “waterfall display” because the older information “fell” toward the bottom of the screen as new data showed up at the top. The video display showed the sounds picked up by
All the sounds they picked up were collected and displayed as bright green lines or wide spots on a ten-inch by ten-inch video screen. Engineers had learned long ago that humans have a keener sense of sight than hearing and had modified sonar systems to take advantage of this natural fact. The louder the signal, the brighter the spot.
Holtzmann had selected a broadband display that was divided into three separate bands. The top one displayed only a couple of minutes’ worth of data, but it was updated much more rapidly than the other two that showed more information. Every few seconds, a new line of data was added at the top, pushing the older lines down.
A dim series of spots could be clearly seen on the topmost band, while it had just appeared on the middle one below. The displayed noise was fuzzy and wide, like the line left by a felt-tip pen on damp paper. A ship, especially a noisy one, would appear as a sharper, brighter set of lines because a ship has many different pieces of machinery, all making noise. This noise-maker was much more limited, weaker.
The next spot appeared on the left side of the display, now bearing three one zero degrees, to the northwest. That meant it lay to port and behind them. As Jerry watched, a new spot appeared, and seconds later, another. The spots didn’t change in brightness, but the line that they drew was angling sharply to the right. That was important. Whatever it was had a high bearing rate, which meant it was fast and close.
“What do you think it is, Mr. Mitchell?” Holtzmann asked.
The bearing rate was the key. The only thing that moved that fast was an aircraft and the only aircraft in this neck of the woods were Russian ASW planes. “A Bear or May patrol aircraft.” He tried to sound confident. “It’s close, too.”
As if on cue, the loudspeaker squawked back to life. “Conn, sonar. Sierra seven six now bears three one five degrees, drawing rapidly to the right. Contact is classified as a Bear Foxtrot.”
“Good guess, sir. Now tell me how they know it’s a Bear?” Holtzmann inquired as he reached up and changed the display to one that showed narrowband data.
Jerry smiled as he admitted his ignorance. “I know it has something to do with the type of engines, but other than that I haven’t a clue of what I’m looking at here.”
Narrowband sensors look for acoustic noise sources that are tightly confined within a very small frequency range. This kind of noise is produced by machinery that operates in a very regular and repetitive manner — like an aircraft’s engines. Both the Tupolev Bear and the Ilyushin May are driven by four large turboprop engines, but the Bear has huge contra-rotating props on each one. The extra set of blades showed up clearly on the display.
“See these four groups of doublets,” Tom said as he pointed to the close lines on the display. “That signal is the sound of his propellers. Each set of contra-rotating blades generates two frequencies that are really close to each other. Only a Tu-142 Bear Foxtrot has that kind of signature. And if we can hear the sound of his props, then he’s close. What should we do?”
Both planes were armed with ASW torpedoes, although there was no risk of attack this far away from Russian territorial waters. A greater danger was posed by the planes’ suite of ASW sensors. They carried radar, an ESM sensor that could detect other radars, and a short-range magnetic sensor called MAD that could sense the thousands of tons of steel in
Had this plane detected them? Were they responding to a report of a Yankee nuke approaching their waters? Or were they on their way home after a training mission? If
“Set up a track, and rig for ultra-quiet,” Jerry recommended.
“Should we change depth?” Holtzmann asked.
Jerry thought for a beat, then said honestly, “I don’t know.” Working it though, he reasoned, “If we go deep, we could get a little farther away from his MAD sensor, but if he drops sonobuoys, he’ll put them on both sides of the layer, and we won’t be able to hear him as clearly on the far side of the layer.”
The “layer,” or thermocline, was a sudden change in the temperature of the seawater that partially reflected sound waves. The depth of the layer varied from day to day, but sub sailors always made it their business to know where it was, and to use it to their advantage. Putting the layer between a sonar and the sub was like hiding in the shadows. It didn’t make you invisible, but it did make you harder to spot.
He paused, then said, “I recommend staying at this depth.”
