The scenes displayed on the large magi-screen were undoubtedly the highlight of the first half of the race.
Instead of just rounding Io Island, the course this time extended to the more distant Toryu Island. The route was set in a figure-eight pattern: the boats would first pass between Io Island and Toryu Island with a right-hand turn, circle Toryu Island to the left, and then pass back between the islands with another left-hand turn to return home.
The eight boats were currently racing toward Io Island at full tilt.
"Go for it!"
"Don't lose, Marcia! I'm rooting for you!!"
"Liche, this is your year to win!"
Crowds had gathered on the shores of Io Island as well, shouting encouragement to their favorite pilots and vessels.
The current standings were 3, 1, 6, 7, 4, 8, 2, 5. Bib number 7, Moburu—wearing a purple swimsuit—was steadily climbing the ranks. The waterwheel on her boat was wider and smaller in diameter than the others, and the golem driving it possessed a sharp, intrepid design.
"That doesn't look like it came from the Marcia Workshop," Jin remarked. As a special guest, his observation immediately drew a reaction from the announcer.
"You're right, Jin-san. While the basic design of Miss Moburu's Bib 7 boat originated from the Marcia Workshop, it was actually built by a workshop in the Celuroa Kingdom."
"I see. That explains the slight modifications to the shape."
The eight boats passed through the Gate without trouble and entered the section of the course rounding Io Island.
"Marcia-oneechan is doing her best."
"She is... Everyone is so amazing."
Hanna and Lishia were transfixed, watching their first-ever boat race.
"A boat from the Celuroa Kingdom... The craftsmanship is certainly high."
Meanwhile, Elsa was observing the Bib 7 boat with a critical eye.
Indeed, I can see the Celuroa Kingdom style in the details. But the most interesting part is the material.
Jin was also silently analyzing the Bib 7 boat.
The surface is metal. It's likely 64 light silver.
A wooden frame with a 64 light silver exterior was an effective way to reduce the water's viscous resistance. Furthermore, when considering the trade-off between strength and weight, 64 light silver was superior to wood. This was because the strength increase gained through Craft Magic like Hardening or Toughening was more effective on metal than on wood.
It came down to the molecular structure. The Reinforce provided by the "net" of free ether was far more effective on 64 light silver, which possessed a simple metallic bond, than on wood, which was a complex organic substance. It was an ingenuity characteristic of the magi-engineering-advanced Celuroa Kingdom.
And the shape of that waterwheel...
Excluding Marcia's own designs, it was an incredibly sophisticated shape. They had likely gone through numerous prototypes to find the optimal configuration. The smaller diameter and wider width meant it was a high-rotation type.
I see. The golem is small too, which makes the whole boat lighter. But a smaller golem has less power. I suppose they're increasing the RPM to compensate for that.
Jin figured that since it was hard to say which approach was definitively better, the final results would speak for themselves. Then, his focus shifted.
Marcia's boat... or rather, the screw. It seems to have a subtle wobble. The balance might be off.
Marcia was using a four-bladed screw. If the size, weight, pitch angle, and surface condition of those four blades weren't perfectly balanced, high-speed rotation would cause vibrations that put a massive strain on the shaft.
She was adjusting it yesterday as well... It might have been a last-minute configuration with no time for testing.
The thought left Jin feeling slightly uneasy.
"I was overtaken!?"
Marcia's Bib 6 boat had just been passed by Moburu in Bib 7.
"Impressive! But I'm not losing yet. Arrow!"
"Yes, Marcia-sama."
Believing that Arrow—the golem Jin himself had worked on—couldn't possibly be outmatched, Marcia decided to kick the speed up a notch.
"Everyone is now rounding Io Island!...Oh! Bib 7 is moving to overtake Bib 6! She's fast, incredibly fast!"
A roar went up from the crowd.
"She passed her! Moburu in Bib 7 moves into third place! But Miss Marcia in Bib 6 isn't giving up! Her speed is rising! They're side-by-side!! It's a dead heat!!"
The magi-screen showed the two boats neck and neck, and the crowd reached a fever pitch at this mid-race spectacle. Bibs 6 and 7 rounded Io Island together and steered toward Toryu Island.
At that moment, Marcia's boat seemed to vibrate violently for a split second. Immediately after, its speed plummeted.
"Oh! What happened to Bib 6!? She's suddenly lost speed!!"
The screw shaft gave out, Jin deduced from the behavior.
A rotating object will vibrate if its balance is poor. This vibration depends on the RPM, and there are specific speeds where the resonance becomes most destructive. It was the same phenomenon as a washing machine drum wobbling during a spin cycle if the laundry was unevenly distributed.
This vibration had led to a fatigue fracture in the screw shaft of Marcia's boat.
"Oh, damn it!"
Marcia checked the screw shaft and cursed her own negligence.
She had adjusted the "horizontal waterwheel"—the screw—so carefully yesterday, but she had noticed a slight warp in the shaft at the time. She was furious with herself for not taking any countermeasures despite having seen the warning sign.
"I have to fix it, fast."
However, the fatigued shaft was on the verge of snapping entirely. She had no materials here to perform a proper repair.
"This is bad... I really need a shaft that's a size thicker..." Marcia muttered, staring at the shaft that was about to be twisted apart by the torque.
"Marcia-sama, it will only be temporary, but please use my left arm."
Arrow made a startling proposal.
"Wh-what!?"
As Marcia stared in shock, Arrow continued calmly.
"My skeleton is made of 64 light silver. Using it, we can repair and reinforce the shaft at the same time. Fortunately, I use my legs to turn the screw, so missing an arm will not hinder our progress."
"Arrow..."
"Since Jin-sama is here, I am certain he can fix me once the race is over."
As they spoke, the other boats passed them one by one.
"Marcia-sama, please decide."
"...I understand. Arrow, I'm sorry."
"Please, do not give it another thought."
Arrow was capable of beginner-level Craft Magic. For a repair like this, beginner-level magic was more than sufficient.
In less than five minutes, the screw shaft was back in place—not just restored, but reinforced.
"We can still make it. Let us hurry," Arrow said, returning to the driver's seat.
Marcia nodded from the cockpit. "No more complicated tactics. We're in last place anyway, so we just have to give it everything we've got. Arrow, I'm counting on you!"
"Yes, leave it to me."
As Arrow stepped on the drive pedals, the screw began to spin with renewed vigor. Bib 6 shot forward as if launched from a spring.
"The emergency repairs must be finished! Bib 6 is moving again! However, she is already in last place, and the gap between her and seventh place is now over a kilometer!"
"It will be interesting to see how she tries to close that gap," the announcer said.
But Jin saw that Arrow and Marcia had resorted to an all-or-nothing gamble.
Go for it, Marcia. Arrow, I'm counting on you.
Bound by his role as a guest commentator, Jin couldn't cheer aloud, so he sent his encouragement from his heart.