Scorpion in the Sea

SIXTY-EIGHT

The control room was darkened down to red lighting to conserve electric power and to reduce heat from the noisy, Russian fluorescent lights. The officers and petty officers of the battle team were pale shadows in the half light, clustered over their instruments and consoles. The hum of electrical machinery permeated the compartment. The Captain watched the visual display of the sonar console intently.

“Classify,” he ordered.

“Sir. Multiple screws, high speed, up doppler, closing from the east. The surface duct carries it clearly, thus deep draft. No merchant ship has that many screws. Classify as target Coral Sea.”

The Captain straightened up and took a deep breath.

“Very well. Track target Coral Sea. Attack director, flood torpedo tubes, open outer doors, forward; open outer doors aft on tube eight.”

“Attack director, aye. Establishing track on sonar target channel one. Opening all forward outer doors. Flooding torpedo tubes one through six and eight.”

The Captain turned and walked over to the plotting table. They were at sixty meters, on the battery, and rigged for silent running. The Captain thought for a moment. What was the accursed destroyer doing? They had remained well clear of the warship, not willing to take the chance of a detection. The destroyer had remained passive, not pinging on his sonar. He ached to take another look at him, but had to steel himself to stay hidden. It was an ominous sign that there was almost no sound from the destroyer. Loitering speed, no engine noises, not even a fathometer.

The presence of the waiting destroyer had thwarted his plans to use the electronic listening buoys. And now he could not know about radars without putting up the ESM mast, and with these flat seas, he was not going to put up anything he did not have to. The destroyer was waiting — but for what? The carrier? But why then the silence?

Twenty-five minutes ago they had heard the deep booming sounds of explosions reverberating along the bottom from the west. The mines had found a victim, probably that large merchant ship. Now the base would be alerted, but, hopefully, unable to dispatch forces with the wreck of the ship littering the river channel junction. The mines had claimed the wrong victim. Inshallah. At any rate, it was more than twenty five miles to the base. With the carrier already approaching, nothing but an aircraft could get out here to interfere. And there should be no obvious tie between what had happened at the river and the Coral Sea. After an explosion that could be heard underwater for twenty five miles, he thought that the base itself might not be operational for a while. Which brought him back to the mysterious, silent destroyer.

“What is the layer?”

“Sir. The layer is at twenty meters, refractive.”

Twenty meters. Effective shielding against a destroyer’s sonar, but not as good as the double and triple layers of the Gulf Stream margins. The plotting team had begun a passive bearing analysis on the carrier; in forty minutes they would have her course and speed, enough to set up the basic firing solution. He would rise to periscope depth just before firing to confirm with a few, quick looks, and then release six steam driven torpedoes down the carrier’s path.

He regretted the loss of the mines. That would have been a nice touch. But then a happy thought struck him: if the base had been neutralized when the merchant ship had struck them, then the carrier could not go home. She would have to stop and wait. In his attack zone.

“Any preliminary estimates of range?” he asked.

“No, Sir,” replied the Deputy from his position at the plot. “It is too soon. The bearing plot shows almost no, perhaps slight right drift, so we should be off axis and in good position. We need—”

The Deputy was interrupted by the sudden sound of the destroyer’s sonar ringing throughout the control room. It sounded very close. Too close. Everyone looked up.

“Bearing of the sonar.”

“Sir: the sonar bears 110.”

“Make your depth 90 meters, and come left to 090,” ordered the Captain. Depth accentuated the effect of the layer, and coming to an easterly heading put the submarine’s narrowest aspect facing the probing sonar, and also helped him close the range to the carrier.

If the destroyer had begun a search, it might mean that he was running out of time to make his attack. The danger was that any maneuver to close the carrier also closed the submarine into the destroyer’s sonar beams.

“Set up a second firing solution on the destroyer,” he ordered.

If he had to, he would smash the destroyer and then attack the carrier.

“Attack director, aye. Establishing second track on sonar channel two.”

“Sir,” reported the sonarman. “The destroyer is occasionally cavitating; his speed is probably right at or above fifteen knots. His screws are nearer than the carrier. His sonar is in the omni-directional mode. I estimate the range to the destroyer by ping stealing to be about 14,000 meters. Sir. We have heard this sonar before. It is the old destroyer.”

The Captain’s eyebrows rose.

“Is it indeed,” he said. “Very well, that is better for us than a Deyo.”

He looked over at the attack director, where the weapons officer was entering and monitoring the two data streams coming from the sonar system. Finally, the weapons officer activated the computer, and the dials began to swing on the attack director. The weapons officer studied the readouts for a moment, and then shook his head.

“No solution, but we are close,” he declared. “I need a stable estimate of course and speed of the target in channel two, and a range estimate for channel one, the carrier.”

“Sonar?”

“Sir: according to the doppler, the destroyer is changing aspect. I suspect base course is westerly, but it is not steady. He is now left of the bearing of the carrier. A few minutes ago he was coincident.”

“Very well.”

The Captain went back over to the paper plot. The passive bearing analysis on the carrier, which was being carried out by one plotter, was a spider web of lines occupying one side of the tactical plot. Passive bearing analysis was always a time consuming process, typically taking one or more hours to compute a refined solution. He did not have the time. The course change to the east, the direction from which the carrier was approaching, would not help the analysis. If anything, the submarine needed to move off the bearing axis in order to develop cross bearings, but that would put her full beam aspect in the path of the probing sonar.

A second plotter had begun a track on the destroyer, taking the bearings from the sonar console as the sonar operator locked in on the point source of the pinging. A destroyer’s sonar in the active mode was always a beacon for a submarine. Better yet, knowing the velocity of sound in the present water conditions, they could make a rough range estimate by timing the individual sonar pings from source to their own hull. But the destroyer was not steering a steady course, which made firing on him a very uncertain proposition.

Tension rose in the control room. The sudden appearance of the destroyer had everyone on edge, especially now that she had begun a sonar search. It was one thing to creep around avoiding detection; it was quite another to set up an attack on a target while a destroyer was hunting you. This was supposed to be an ambush of an unsuspecting, capital warship in peacetime. The persistent pinging from above indicated that the other side might be aware that there was danger here.

The seams of the submarine began to creak as she descended to 280 feet. No one was worried about crush depth. The problem now was the proximity of the bottom. The Musaid perched on his stool, his legs spread in front of him to keep from sliding forward as the deckplates dipped, his gnarled hands gripping the stainless steel seat of the stool as he fixed his eye on the depth gauge and the diving plane indicators.

“Depth is 90 meters,” he announced softly. “Request permission to trim aft.”

“Permission to trim.”

The Captain continued to study the nascent plot. Too soon to develop a clear picture. He began to conjure one up in his mind. The big carrier plowing westerly towards her base. Ahead of her a destroyer had begun his screening work. If indeed he was screening, then he would generally match the carrier’s expected route. Track the destroyer and obtain attack geometry on him, and that would also serve as a good estimate for the carrier. As long as the destroyer did not detect the Al Akrab.

“Bring me the most recent BT trace,” he ordered.

The senior sonarman collected a piece of paper from the sonar console and presented it to the Captain, who studied it carefully. A bathythermograph, or BT trace, was a plot of temperature versus depth, obtained by firing a thermocouple probe attached to a wire out of the submarine into the depths. It recorded the thermal structure of the ocean until the wire broke off. Kinks in the trace indicated thermal layering, and thereby the depths of relative safety for submarines. This plot showed only one layer, and not a strong one at that, fifty to sixty feet below the surface. Better than nothing, he thought. Some of the destroyer’s sonar energy would be refracted back up, creating acoustic shadow zones underneath the layer where strong returns would not materialize.

But he could not count on that for very long, especially as he was headed towards that sonar. At some point, the energy levels of the returns from the boat would break through the acoustic mirror surface, and they would be in trouble. He stared down at his shoes in the red light. He would have to deal with the destroyer, sink him if possible, or disable him at the least, in order to get a free shot at the carrier. If the destroyer made a detection, the carrier would be warned and would speed away, out of range, wrecking the mission. But timing was crucial — a premature attack on the destroyer would produce the same results.

“Is the carrier continuing in on her original course?”

“Sir,” said the Deputy. “We cannot tell her precise course, but the rate of her bearing drift is fairly constant, which would indicate—”

“Yes, that she has not changed her course; I understand the basics,” interrupted the Captain, annoyed by the pedantic response from the Deputy.

“Make ready tubes one and two; I intend to fire at the destroyer as soon as we have a reasonably good solution on him, and some idea of the range to the carrier. Give me a southerly course recommendation that will put the destroyer and the carrier on the same bearing; when we achieve that geometry, I will fire two torpedoes on wire guidance at the destroyer. If they miss, or he evades, I want them redirected down the bearing of the carrier. Set the running depth for one and two at four meters; select wire guidance. Retain the settings on the remaining four tubes at seven meters. Make haste!”

The Captain walked back over to the sonar console, and studied the bearing traces. The weapons officer set up the running depth settings for tubes one and two, transmitted them to the torpedo guidance systems, verified continuity between the wire and the guidance modules, and initiated warmup power to the computers in the two torpedoes.

The Deputy and the operations officer scrambled to work a maneuvering board solution. They could estimate the range to the destroyer, but not to the carrier. In order to start the problem, the operations officer postulated that the carrier was twice the distance of the destroyer. If the destroyer was about six miles away, and closing, then the carrier was about twelve miles away, also closing. They looked across the table at each other and agreed on the assumptions; with hard data absent, they made estimates in order to set up trial geometry.

The Captain watched the bearing traces, and listened to the audio from the passive sonar. From the sounds of the screws, the carrier was going faster than the destroyer. She would also be overtaking her because the destroyer was changing course often as she worked her search pattern out in front of the carrier. He walked back over to the plot.

“What is the best range estimate you have on the carrier,” he demanded.

The Deputy looked up at him and shrugged. It was far too soon. The Captain leaned forward and put his thumb down in the middle of the spiderweb of bearing lines.

“What is that range? Now!” he hissed.

“Sir, that range is—”

The Deputy measured quickly with the protractor arm.

“—approximately thirty-two thousand yards. But—”

“Yes, I know. Keep refining it. And the range to the destroyer?”

“Sir. From ping stealing we have 12,000 yards. But his course is unstable. Widely unstable. It would be useless—”

The Captain spun away from the plotting table, and went to the attack director’s console. The persistent pinging of the sonar was getting louder. It was only a matter of time before there would be a shift to directional pinging and the dreaded click of contact.

He stared down at the weapons console. The submarine’s sonar was feeding direct bearing inputs to the weapons console for both targets. The big torpedoes could go fifteen miles at their best speed of almost 55 miles per hour. They knew the destroyer was closer than that. As long as they had the bearing information, they could steer the big fish using the wire guidance system right down that bearing towards the source of the pinging. As long as the wire did not break, they could not miss. But the range to the carrier was uncertain. If they hit the destroyer, or missed and alerted him, the carrier could run back out of range faster than either the submarine or the torpedoes could catch her.

“We must wait until the carrier is closer,” muttered the Captain. “I did not come out here for some ancient destroyer. What is the bottom depth?”

“Sir, the bottom depth here is 140 meters, and there is a ridge 4000 yards to the east of us that is 120 meters.”

“Very well. Musaid: make your depth 125 meters! Deputy, I need that course recommendation, now.”

There was a stunned silence in the control room. The Captain was ordering a depth that was within fifty feet of the bottom, with a ridge ahead that stuck up off the bottom higher than their ordered depth. The deputy blanched, and consulted quickly with the operations officer.

“Sir. We recommend 190 to make the carrier and the destroyer tracks coincide.” And to miss the ridge.

“Very well, come right to 190. Deputy, refine your calculations as the bearings develop. Musaid. Report when your depth is stable at 125 meters.”

“Sir. Flooding trim tanks forward to achieve 125 meters while we turn. Trim should be sufficient.”

“Very well. Now: we wait for a few minutes, to let the carrier get closer. Then we will attack the destroyer. I will have some tea.”

The messenger of the watch gawked at him for a second, along with several of the officers. It hardly seemed the moment for a cup of tea. The Musaid smiled at the Captain’s insouciance, understanding the gesture. He prodded the messenger with a boot to go fetch tea. Everyone else waited and watched in silence, as the depth gauge crept around to 375 feet, and the pinging from the destroyer’s sonar grew inexorably louder.