Chapter 1531 Today I have a long tassel in my hand

In fact, as a submarine commander, Sato is not a reckless person.

The series of decisions he made all had a common premise, that is, the helicopter that took off from the Hyuga assured them in the last directional communication that the Chinese interception fleet had been lured away, so the submarine should currently be in a very mysterious state.

Even so, the Canglong did not completely relax its vigilance.

After recovering the towed linear sonar, Yamamoto has adjusted the sensitivity of the side and bow sonars to the highest level, constantly monitoring targets within dozens of nautical miles around.

On the electronic nautical chart, several symbols of different colors represent ships of different natures in the nearby waters, but all are judged to be low threats.

"They are all fishing boats and cargo ships. The sound signature of low-speed diesel engines is very obvious." Yamamoto reported, "The few targets using medium-speed engines are all government ships with very low levels of armament, and they are very far away."

Except for a few old-model frigates, the Chinese Navy's main combat ships have been fully equipped with gas turbines, which saves a lot of trouble for the opponent's sonar system.

"Mr. Sato." Deputy Captain Onodera came forward at this time, "Should we move closer to the nearby shipping route?"

Seeing that the other party did not comment, he continued, "If we can find a suitable bulk carrier or tanker as cover, we can sail at a higher speed, and even surface after nightfall to use the snorkel to charge."

Using noisier civilian ships to cover their tracks is a specialty of submarines in various countries.

But after thinking it over, Sato rejected the other party's proposal: "Being too close to the cargo ship will make it difficult for our passive sonar to work, and we will completely lose the initiative. In addition, the civilian ship's route overlaps with ours very little, and we won't save much time going back and forth."

Onodera did not continue to insist, but his expression changed slightly -

Five years ago, the Asashio submarine collided with a cargo ship during a similar training exercise. Sato was supposed to be the chief engineer on that submarine at the time.

Therefore, he felt that the other party was speaking in high-sounding terms, but in reality they might just be worried about another collision with a cargo ship.

Sato seemed to feel a little guilty. After a moment of silence, he came back to the mountain and put his hand on the other person's shoulder: "After we enter the deep water area, release the towed array sonar again..."

Time passed by minute by minute.

The speed of 5 knots is actually not much faster than a person jogging. It was not until three hours later that the Canglong left this complex area with an average water depth of less than 90 meters and entered the edge of the Zhongsha Trough.

As the drum of the retractable system slowly turned, a 100-meter-long cable stretched out from the reel at the bottom of the Canglong boat again, floating lightly in the cold sea water behind it.

The performance of this system is similar to that of the British Navy's Type 2076 integrated sonar, which can capture surface targets using gas turbines up to 75 nautical miles away, enough to provide the Soryu with room to maneuver.

However, the moment the sonar was activated, Yamamoto's body tensed up instantly:

"Captain, the sonar detected three new targets at a distance of about 55 nautical miles, a speed of 20 knots, and the acoustic signature is that of a gas turbine." His voice was filled with obvious nervousness.

Except for a very small number of special models, civilian ships do not have the financial resources to use gas turbines as power.

Kenji Sato leaned over the chart table and asked, "Can you identify the model?"

"There are two civilian ships interfering in the middle, so it's hard to filter it out." Yamamoto adjusted the filter, "But it's certain that it's not the Annan Navy's Cheetah-class. It's either the Chinese Navy... or the Hyuga fleet is here to pick us up."

"The Hyuga formation seems to be further east, and shouldn't be sailing north..." Sato pondered for a moment, and finally gave the order: "Reduce the speed to 2 knots, depth to 150 meters, shut down the Stirling engine, and switch to battery power."

The submarine, like a deep-sea fish sensing danger, began to dive silently into deeper water layers.

Sato stared at the sonar screen, watching the three spots approaching. "Keep absolutely silent," he whispered, "If they are really Chinese warships, they should not be far enough to detect us."

……

However, what Sato didn't know was that at higher altitudes, two newly arrived anti-submarine aircraft had almost locked onto his position.

One of the Air-Submarine 200A aircraft was equipped with the latest optically pumped magnetometer for testing, with a detection accuracy of an astonishing 0.001nT.

"The target has been locked within 1 nautical mile." The weapons operator on the anti-submarine aircraft reported, "but the target is estimated to be increasing its diving depth, and the magnetic signal is obviously weakening."

Captain Chen Zhuo quickly contacted the fleet: "Taishan No. 3 calling Longgong, the target dived to the deep water area, requesting the deployment of sonar buoys."

Yang Yuelun sat in the combat command center of Star City, staring at the constantly updated data on the screen.

The formation was already close to 50 nautical miles away from the designated sea area, and it was almost impossible for the target to escape.

"Approved to drop." He ordered, then turned to Captain Zhao Gang beside him, "The fleet advances at full speed, and must blockade the relevant sea areas before the anti-submarine aircraft runs out of time!"

On the Taishan-3 anti-submarine aircraft, Chen Zhuo, who had obtained permission, could finally let go and do something big:

"First, drop a water temperature measuring buoy to confirm the location of the transition layer."

A few minutes later, the first batch of buoys fell into the sea and began to sink to different depths.

The Canglong, located underwater, captured the clear sound signal at the first moment.

"Something was thrown into the sea." Yamamoto's breathing became rapid. "It's not a torpedo because it has no propellers."

This was hardly good news. Sato almost felt dizzy: "Anti-submarine aircraft?"

He originally thought that the aggressive Chinese fleet was returning after completing the interception mission, and that he only needed to avoid its sharp edge to get through safely.

I didn't expect that there was a devil hovering over my head.

They were actually coming for this ship of theirs.

Apparently, something had gone wrong with the Hyuga's assurance for some reason, and the Chinese had probably known about the existence of such a submarine a long time ago.

However, Kenji Sato had no time to think about where the problem lay at the moment. The most urgent task was to solve the current trouble.

"Dive to a depth of 230 meters, use the water temperature jump layer to protect us, and turn on the multi-beam navigation sonar to find a suitable position and prepare to sit on the bottom."

He knew that the Chinese Navy had not yet mastered the detailed underwater topographic features of the nearby area, and it would be difficult to find a completely stationary conventional submarine that was seated on the bottom.

However, the operation of the Canglong had been predicted in advance by the Taishan-130, and the data from the water temperature measuring buoy was quickly transmitted back - there was an obvious water temperature jump layer at a depth of 150- meters.

"The target should be hiding below the jump layer." Chen Zhuo analyzed, "Deploy dynamic direction-finding sonar buoys and active continuous sonar buoys in groups, one group with a fixed depth of 90 meters, and the second group with a depth of 180 meters."

As the order was given, more than a dozen sonar buoys were dropped into the water one after another.

After reaching the set depth, the continuous sonar buoy begins to emit regular sound waves.

At a depth of 230 meters underwater, these sound waves were like invisible tentacles, constantly hitting the hull of the Canglong.

"Bang-bang-bang" The dull and continuous impact sounds echoed inside the submarine, and every crew member held his breath.

Kenji Sato gripped the armrest tightly, his face solemn.

"They're mapping out the seafloor," he whispered. "They haven't locked onto us yet, but time is running out."

Just as he was struggling over whether to take the risk and continue diving, Yamamoto's voice suddenly sounded again:

"Captain, the sonar detected an underwater hill at a depth of about 250 meters. The terrain can provide us with cover!"

Sato quickly checked the 3D simulation image generated on the multi-function display, and a plan formed in his mind.

"Advance to the hilly area and hide!" he ordered.

The Canglong was like a wounded whale, crawling slowly and arduously towards the underwater hills.

When it finally landed successfully, everyone on the boat breathed a sigh of relief.

Almost at the same time, two strong sound waves with an interval of 6 seconds hit the hull.

This is a pulse signal sent by an active positioning sonar buoy, generally used for final positioning before launching an anti-submarine attack.

"Did they discover us?" asked the deputy captain Onodera nervously.

Sato shook his head: "Not necessarily. We are on the reverse slope. The terrain can provide some cover. Besides, this is not the enemy's territorial waters. They can't easily launch an attack."

He was originally trying to comfort the other crew members, but what he said at the end actually gave him a lot of confidence: "We will crawl above the seabed at a speed of 2 knots to see if we can use the terrain to cover us and escape from the search range..."

……

On the water, Chen Zhuo was reporting to Yang Yuelun:

"Ryugu, we can confirm that the target is within 5-6 chains nearby, but the other party should be hiding under the underwater terrain, so we can't provide more accurate location information for the time being... In addition, we don't have much fuel left, and we have to return within half an hour."

In fact, anti-submarine attacks themselves have great uncertainty. If used in actual combat, the submarine search accuracy of about half a nautical mile is enough to drop a few anti-submarine torpedoes or air-dropped depth charges for attack.

It’s just that it’s impossible to really use force now, which gives the other party the opportunity to cheat.

Fortunately, the fleet had anticipated this.

……

A few hours later, the Zhu Kezhen and Taocheng finally arrived at the designated sea area.

In the hydroacoustic laboratory, engineers are debugging a special system called "Zhenhai No. 1".

Its original function was to emit a series of complex waveforms to map out high-precision underwater topography information and even detect the material of the seabed surface covering.

But no one could have imagined that the first use of this equipment would be for anti-submarine purposes.

"Frequency modulation is complete, and the waveform library has been loaded." Chief Acoustic Engineer Tao Xiuyun reported, "But the effect... has not been tested yet."

This waveform library was not even transmitted to the fleet via data link until after the ship set sail, so of course there was no chance to fully test it.

The only reassuring thing is that the entire plan is said to have come from the hands of an academician and should have sufficient theoretical support.

"The target's confirmed range is here... We set up three acoustic barriers along its possible route." Captain Zhou Yi looked at the sea chart and repeated the plan. "First is the shoal trap, which simulates a sudden shallowing of the seabed, forcing the submarine to slow down. Then there is a series of virtual deep-sea mountains and a complex underwater maze."

"Has the thermocline data been transmitted?" Tao Xiuyun asked.

"The transmission has been completed." A young technical officer behind him replied, "There is a preset plan in the waveform library that can form directional interference through the thermocline...at least that's what the report says."

The situation finally began to change decisively.

Inside the Soryu, Yamamoto Koichi suddenly found that the display screen in front of him became a mess.

"Captain! The terrain is abnormal, slow down!"

Sato Kenji rushed to the screen and was shocked to see that the flat seabed terrain had turned into a completely unfamiliar scene.

A towering ridge suddenly appeared right in front of the submarine, like a cliff.

"How is it possible?" He looked around blankly, "How could there be such a structure on the seabed... and it's not even on the nautical chart?"

Most changes in underwater topography come from undersea earthquakes and volcanic activity, which generally tend to form gullies rather than hills. Although the nautical chart from the 70s was inaccurate, it was unlikely to miss such obvious features.

But the ping-pong noises that continued for several hours above his head had upset him. He really didn't have the extra energy to think about too many details, so he just gave the order instinctively:

“Redraw the surrounding sea charts.”

But the "terrain" shown by the sonar became more and more chaotic, as if entering an underwater maze.

It even reminded Sato of the movie "Twenty Thousand Leagues Under the Sea" that he had watched in school, in which there was a complex underwater cave.

Fortunately, judging from the 3D simulation map, the gully here is large enough, and there is an almost straight channel about 60° to the left front that extends for at least several nautical miles, which can be used to block the sonar signals from above.

It's the perfect escape route.

Given the complexity of the terrain, as long as we can get a few miles away from the sonar area, the other party will no longer be able to find us.

Sato, feeling that God was helping him, quickly gave the order:

"Turn left 60 degrees and increase speed to 4 knots!"

However, this decision led to disaster.

About half a minute later, a sharp, piercing sound of metal tearing echoed throughout the submarine, followed by a chilling alarm.

The red emergency lights illuminated every confused face in the command cabin.

Sato's mind went blank in an instant.

After forcing himself to calm down, the first thing that came to his mind was that the other party might have launched a torpedo.

But the sound just now did not sound like an explosion, and even a 324mm light torpedo would be fatal to a 3000-ton submarine.

Before he finally realized what was happening, the intermittent call suddenly rang:

"This is the torpedo room. The port side of the bow is severely damaged. We are carrying out damage control. It should be...it should be a collision!"