Why the Union could supply ironclad machinery

Why could the Union produce ironclad engines more readily than the Confederacy?

Northern civilian steamship and railway industries had already created the machinery, skills, and infrastructure needed for naval production.

Late Confederate ironclad designs could be formidable, but suitable machinery was a persistent constraint. The northern states already possessed extensive steamship activity on rivers and lakes, followed by a growing railway sector. Those civilian industries supplied engines, skilled labor, and accumulated technical experience that could be redirected toward naval construction. Infrastructure can support military production whether civilians or the government built it, and the Union had that technical base in abundance.