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.
