Life of Being a Crown Prince in France

Sane looked at the Crown Prince with confusion: "Iron shell? What do you plan to use it for?"

Joseph replied without hesitation: "Of course, it's to resist cannonballs."

Sane shook his head with a smile, equally without hesitation: "That's impossible, Your Highness. Even to defend against cannonballs shot from a distance, say a 24-pounder from 500 meters away, you need at least 5 centimeters of thick iron plate."

He quickly calculated in his mind: "This would add at least 250 tons to a fourth-level battleship. You know, even though the propulsion of steam battleships is quite strong, such heavy load would reduce its speed to below 9 knots, and seriously affect the carrying capacity for coal and supplies."

He spoke rather politely, but in truth, a fourth-level ship with a displacement just over 1,000 tons, if the armor alone weighs a quarter, would hardly be navigable.

Joseph nodded with some regret, "Ironclad" ships seem out of reach in the short-term.

Moreover, 5 centimeters of armor is insufficient. He recalled that historically, the "Napoleon" had armor of 10 to 12 centimeters, capable of resisting the direct shots from a Russian Army 32-pounder. It was then truly of practical value.

The main issue is still the steam engine's power, otherwise even heavier ships could be propelled by significant force.

Sane comforted the Crown Prince: "Your Highness, if you want to enhance protection, we can at most increase the steam battleship's hull by another 4 centimeters thicker, meaning the oak hull."

Joseph sighed, the additional few centimeters on the wooden hull would hardly have an effect, at most strengthening the defense against cannons under 12 pounds. While in battleship engagements, the main weaponry is cannons over 24 pounds.

He casually asked: "How much heavier can new ships weigh compared to regular fourth-level ships?"

"About 25 tons, Your Highness."

This weight is barely worth mentioning...

"Wait a minute." Joseph suddenly stopped walking, who said this weight couldn't be utilized, he thought of iron ribs.

In this era, the structure of warships is basically to first lay a thick keel, the main support frame at the bottom of the ship. Then along the keel, every 0.7 to 1.5 meters, install a pair of arched ribs from the bow to the stern. And the hull is supported by these ribs.

Currently, ship ribs are all made of oak. If replaced with iron, it can greatly increase the ship's defense—

If enemy cannonballs hit the position of iron ribs, they are almost impossible to penetrate. Even the oak hull within a dozen centimeters front and rear of the rib will become substantially more resilient due to strong support.

In other words, nearly half of the ship will transform into an enhanced defense area!

Joseph didn't bother calculating himself, directly asked Sane: "If all the ribs on the ship are replaced with iron, how much weight would be added?"

Sane couldn't respond "instantly" this time, because ribs are curved, accurate calculations require calculus.

After seven or eight minutes, Sane looked at the calculation results in his notebook and said: "About 15 tons, Your Highness."

"That means it's totally bearable." Joseph said excitedly, "Then we'll replace all ribs with iron, this will greatly enhance the ship's defenses."

Sane froze for a moment, then shook his head: "Your Highness, I'm afraid it's not feasible."

"Oh? Why?"

The chief designer patiently explained: "Your Highness, you know that iron items on the ship rust very easily, especially the ribs that soak partially in seawater—this stems from the hull needing to take in ballast water when empty—which makes the situation more severe.

"Moreover, ribs are load-bearing components, even if they rust one-fifth, they will struggle to support the ship's structure, possibly leading to severe warping of the hull.

"In fact, the Spaniards once used iron bolts to strengthen the connection between ribs and keel, as a result, they had to replace all bolts every three months. Later, they had to switch back to wooden wedges."

The humidity at sea is very high, and the air contains salty water vapor, causing iron items to rust extensively.

Joseph immediately thought of stainless steel, but the Namura Steel Factory has only produced manganese steel so far, stainless steel is nowhere in sight.

Recalling various rust prevention methods from later generations, he quickly found one he could use: "We can protect the iron ribs with sacrificial anodes."

Sane blinked: "You mean, sacrificial… anodes what?"

"The essence of metal rusting is losing electrons to oxidization…" Joseph said just one sentence and stopped, "The principle can be elaborated by Mr. Coulomb.

"In practice, it's about adding a block of zinc to iron components, better if galvanized. This way, 'rusting' occurs to the zinc block, while iron remains intact."

Hmm, explaining the "galvanic cell effect" is too complicated, mainly because people of this era barely have a concept of electricity. If you tell them about donating electrons from a metal more active than iron, to protect iron from participating in oxidation reaction, they might listen as if they haven't.

Sane naturally nodded mechanically: "You, are sure this works?"

"Of course, you can verify by experiments yourself." Joseph said, "In the future, just need to periodically replace anodes… uh, meaning replace the consumed zinc blocks."

Sane's eyes started shining. The Crown Prince's academic reputation he had long been aware of to the point of weariness, now filled with excitement, having no doubt—he as a ship design expert naturally understands the significance of replacing all ribs with iron.

He promptly added: "Your Highness, if steel materials can be used extensively, then 'rib beams' can also be swapped for iron, further increasing defense density. Probably adding another five to six tons."

Rib beams are the transverse beams between ribs, also capable of resisting cannonballs.

Before Joseph could speak, Sane slapped his thigh forcefully: "Furthermore, the rivets needed for copper plating at the ship's bottom can be replaced with iron, reducing rivet density by about 30%, significantly speeding up construction."

Joseph didn't quite understand: "You mean rivet density is?"

Sane hurriedly explained: "Your Highness, you previously ordered copper plating for all warship bottoms, and because iron rivets rust easily, we have to use brass rivets to secure copper plating.

"You know, brass is very soft, to ensure copper plating doesn't fall off, rivet density must be increased.

"But now, with your rust prevention method, we can use hard iron rivets."

Joseph praised the chief designer's ability to utilize new technologies but immediately thought of another issue: "Wait, you mean the current rivets fixing the copper at the ship's bottom are brass rivets?"

"Yes, Your Highness."

"Then the copper's material is?"

"Also brass, Your Highness."