Otherworld Bone Dragon Operation Guide

Chapter 73 Sonar and Thermocline
Su Ming activated the gyroscope to continuously record the White Triangle's flight path.

Sivor glanced at their controls, clearly not understanding many of the things, but didn't ask a single question. He walked to the operations room behind the cockpit and sat down.

After completing the operation of the White Triangle, Su Ming also arrived at the operations room.

"Based on the current information, the sea monster has many characteristics of an octopus." Siwo pointed to the painting on the table, "The tentacles are very similar to arms, and there are eight of them."

“It’s just that its size is way beyond that of a normal octopus,” Su Ming said.

The white skeleton brought over tea, and Violet placed it on Xiwo's plate. "Have a drink of water first, Grandpa."

Siwo picked up his teacup and glanced outside the cabin. "Twenty-four knots?"

Su Ming glanced back at the ship's speed log: 24.2 knots. "Yes."

"Impressive! No wonder those forces were willing to drop the warrants and beg for your help," Siwo said. "Do you have any methods for searching for the sea monster?"

“There’s a towed sonar at the stern,” Su Ming replied. “The specific effectiveness of this system hasn’t been tested yet, but preliminary estimates suggest it can detect targets over seven kilometers away in active mode.”

Siwo looked surprised. "The younger generation is truly formidable!"

Su Ming looked at Zi Jin, "Should we tell him?"

The girl shook her head. "Grandpa already has a suspicion in his mind, but we don't need to explain. Talking too much about irrelevant things will only drag him into it."

“I’m not afraid of this old body, it’s just that Xiao Jin’s troubles are getting bigger and bigger, and I’m already feeling helpless,” Xiwo said.

"So, the cleaner my identity, the more I can help you. This sea monster incident is definitely an important opportunity for you."

None of the three pursued the topic further.

"There's still room for improvement in the ship's speed, and the sonar has a passive mode that needs to be tested," Su Ming continued. "Also, regarding the underwater sound convergence zone—"

Suddenly, Siwo's eyes lit up. "You actually know this too!"

Ocean exploration is far more challenging than air exploration, as the temperature and density of seawater vary with depth. Sound traveling through the ocean is subject to strong reflections and deflections, producing a wide variety of effects.

In summary, due to these complex phenomena, sound rays from different pathways can converge over a certain distance, forming a localized area of ​​high sound intensity. Under normal circumstances, this convergence occurs over a distance of approximately 50 kilometers.

From a sonar perspective, the advantage is that it can detect a ring-shaped area more than 50 kilometers away.

Of course, outside the high-intensity zone is the low-intensity zone, also called the sound shadow zone, where sonar cannot detect signals.

"With such a large detection ring," Siwo exclaimed, "the difficulty of searching for the sea monster has decreased far more than I anticipated!"

Su Ming unfolded the sea area sand table. "The area where the sea monster is currently found has a diameter of 800 kilometers. The latest ship involved in the accident is here." He pointed to one of the spots. "We are about to enter the sea monster's activity range. It's about time to deploy sonar."

"Do you need any assistance?" Violet asked.

"No need, Xiao Hei and Xiao Bai can help," Su Ming replied.

Su Ming, with the skeleton in tow, deployed the sonar into the water and released the cable. When the sonar probe reached a depth of 1000 meters, he activated the equipment. "That's a good idea!" Siwo praised. "Placing the sound detection device far below the seasonal thermocline is a good way to eliminate shallow sound shadow zones!"

The thermocline is the region where seawater temperature and density change most dramatically, causing sound waves to be strongly refracted and losing a significant amount of energy. The thermocline creates a blind spot in sound detection, which must be considered when using sonar equipment.

"You have a deep understanding of marine acoustics." Su Ming was actually more surprised.

“Exploring the ocean will inevitably lead to the path of sound,” Siwo sighed. “I’m very good at sound-based magic and always thought I was the one who had gone the furthest in this area, but I didn’t expect that someone already had the standard answer ahead of me.”

"No, I only know a little bit about it. I can't even explain how the sound shadow zone is generated." Su Ming wasn't being modest; he was just reading from the sonar user manual.

"You also have a way to deal with permanent thermoclines?" Siwo asked.

Su Ming shook his head. "My sonar can indeed be deployed to a depth of 2000 meters, reaching below the permanent thermocline, but then it won't be able to detect shallow water layers."

Siwo thought for a moment, “Given the size of this sea monster, it is most likely a deep-sea creature.” He pointed to the nautical chart, “The average depth of the area where it appears is about 3000 meters, which is a suitable range. We should place the sonar below it.”

“I think we only need to consider detection above the permanent thermocline,” Zijin objected. “At such a depth, it would be extremely difficult for a sea monster to go up and down. If it came directly from the deep sea, it would die from its own internal pressure!”

Su Ming really wanted to complain; this thing didn't seem to follow basic biological laws at all. However, after thinking about it, Siwo agreed with Zijin's opinion, so the sonar remained at a depth of 1000 meters.

They soon approached the target sea area, and Zijin saw some wreckage floating on the sea surface through her binoculars.

“I want to go and take a look,” Sivor said. “Because other ships don’t dare to come, I’ve never been to the site to examine the wreckage of the damaged ship.”

"Wouldn't it be dangerous to stop the boat?" Violet asked.

“The White Triangle needs time to start and accelerate,” Su thought for a moment. “I can slow down and circle around the area while you investigate; that would be safer.”

"This method will work."

Su Ming reduced the ship's speed to 15 knots and began circling the wreckage area to maintain the ship's maneuverability. Zi Jin and Xiwo took out brooms and flew towards the wreckage to begin their investigation.

This was a fast sailing ship of about 600 tons, structurally reinforced, but it was ultimately torn apart by a sea monster. Nearly half of the hull is floating on the surface, bobbing with the waves. There were no bodies at the scene; it's likely that the sea monster swept it away and swallowed it.

White dots flashed across the sonar screen from time to time, but they were all very small targets or noises. Su Ming thought for a moment and began to adjust the ship's course, and the white triangle's track began to spread outward.

"[Purple Violet, I'm moving out a bit to increase the perimeter.]" Su Ming messaged Purple Violet.

[Doing a broad search? I understand.] Violet paused for a moment. [Sorry, Su Ming, I didn't tell you beforehand that Xiwo was coming. Actually, I already guessed that Grandpa was coming; he would definitely come to see me.]

Su Ming was puzzled. "Why apologize?"

I often forget that you are the master of the Bone Mark, my controller.

Su Ming was even more puzzled. "You know I've never considered myself a controller or anything—I've always thought of us as great partners!"

(End of this chapter)