Sound, of course, traveled quite well underwater, and sound was a submarine's worst enemy. If Pittsburgh's sonar could pick up Randall's signals, it was a sure bet that any Soviet underwater listening devices would as well.
The signal, though, was deliberately simple, the Morse letters E-I-E. To the uninitiated, they might sound like random noise, would probably be overlooked entirely.
Rodriguez aboard the Pittsburgh, however, would be listening for exactly that signal, and his computer could be set to sort the clicks out of any background garbage more precisely than even the best-trained human ear.
With luck, Pittsburgh was already very near, and getting closer.
It would have been simpler, of course, to have secured the float by a safety line to Pittsburgh's conning tower and homed in on that … but if a Russian ASW patrol had shown up and Pittsburgh had been forced to run, float and line vibrating in the conning tower's wake would have created an unmistakable and easily tracked sonic signature.
And so they had to do it the hard way.
After perhaps five minutes had passed, he pressed the button again. Click, click-click, click. And repeat. And wait a longer period of time, and repeat.
McCluskey touched his elbow. "There, sir."
Dimly seen in the overcast darkness, but very faintly luminescent in the oily waters, a single periscope rose from the swell, its surface dappled a camouflage dark gray on medium gray. They motored closer, and Nelson rolled over the side, taking a line with him which he secured to the boat's sail just beneath the surface. The others began donning their rebreather gear and making ready to collapse and secure the IBS.
It was going to be damned good to be safely home once more.
"Divers are aboard, Captain," Latham reported.
"Let's get her out of here," Gordon told the XO. "I want a bit more space between keel and bottom."
"That'll feel damned good, sir. It's pretty tight in here."
"Maneuvering, Conn. I want turns for twelve knots."
"Conn, Maneuvering. Turns for twelve knots, aye aye."
The four SEALs entered the Control Room from aft, wet, and looking both tired and a bit bedraggled. Gordon caught Randall's eye as the other three filed past, heading forward and down to the torpedo room. "How did it go, Mr. Randall?"
"Well enough, I guess, sir," Randall replied. "They looked like a pretty rough bunch. Streetfighters and brawlers, rather than fishermen, is my guess." He shrugged. "But everything seemed up and up. They knew the passwords."
"I suppose the spooks know what they're doing."
"You don't sound all that sure, sir."
"This vessel is at stake, Mr. Randall."
"I understand, sir."
"It's 0040, Mr. Randall," Gordon said, glancing at the big time readout on the forward bulkhead. "It'll be tight getting you in to do any useful work at your AO tonight, and still have time to get clear before daylight."
"Frankly, sir, I think we need some downtime. We did our swimming thing for tonight."
"Understood." What Randall and the other SEALs had just done — locking out, deploying an IBS, making contact with Stenki, returning to the "Burgh, and locking back aboard — and all with the possibility of combat or missing the pickup hanging over them — was enough stress for anyone for one night, even a SEAL. "Get some sleep. We'll plan an approach to Objective Mongol tomorrow."
"Thank you, sir."
"Conn, Sonar," sounded over the intercom. "Sonar, Conn. Go ahead."
"Multiple contacts, sir, bearing two-nine-five through three-three-zero. I have three… no, make that four contacts. Designating Sierra Two-eight and Sierra Two-nine. The other two are old friends, Captain. Sierra Two-one and Sierra Two-four. I make them as light ASW assets, frigates or large patrol boats. On a southerly heading… making turns for about fifteen knots."
"How far?"
"I'm picking this up through a CZ, Captain. Hard to say, but my guess is thirty to thirty-five miles." A convergence zone.
Sound waves propagated well through water, but the colder the water, the slower the wave. Cold water tended to bend the moving sound wave downward, refracting it the same way a lens refracted light.
Increasing water pressure, however, tended to refract the wave back up… though at a much lesser rate than the decreasing temperature. Eventually, though, the wave headed back toward the surface… to be bent downward once more when the pressure was low and the temperature dropping.
The result was a kind of a sine wave through the ocean, between the warm surface layers of the water and the ice-cold depths. A listening sonar could detect undersea sounds from astonishing distances, if that sonar was in the convergence zone of the sound, with the wave passing through that depth at that point. If the listener was a little ahead of the wave, or a little behind it, in the empty trough between crests, the sound would pass by and never be detected.
The oncoming Soviet vessels posed no immediate threat. They were an hour away or more, at least, and Pittsburgh would be long gone from the area by the time they could arrive. In any case, their due-south heading was not directly toward the Pittsburgh, but toward a point some miles to the west. Nor could they hear the American boat. While convergence zones worked both ways, the Russians were moving too fast to be able to hear much, if anything, through their sonars.
But Gordon couldn't help wondering what they were doing, and why. Light ASW assets… on routine patrol? Unlikely. A patrol would be conducted at speeds low enough to allow them to use sonar.
Moving into position for an ambush, perhaps, an ambush directed at the Pittsburgh? Or — disquieting thought — at the resistance fishing trawler, and the CIUA men aboard her?
Whatever they were, they were not good news.
"Engineering!" Captain First Rank Anatoli Vesilevich Vetrov shouted into the microphone. "More power!"
"Sir," Filatev, the Engineering Officer replied, "we are at one hundred ten percent now, and I can hold it here for only a short time. The cooling assembly…
"I want one hundred fifteen percent on the reactor now, damn you, or I'll see you in Hell!.. "
The Krasnoyarskiy's captain was aware of the silence on the control deck, of the eyes fixed on him as he leaned against the housing of the vessel's Number 1 periscope. He sensed the fear there. Good….
"One… one hundred fifteen percent on the reactor, Captain. I will require the order in writing."
"It's logged," Vetrov spat, and he clicked off the intercom.
"Stations!" he bellowed at the watching bridge crew. "We will not catch the American dogs with you gawking like schoolchildren! There are still billets within the Gulag for men who shirk their duty!"
He caught the hard gaze of Starpom Felix Nikolaevich Salekhov, his Executive Officer, and watched the other man's mouth harden into a thin line. No matter. Vetrov required no man's approval. He required only obedience… and results.