Ship replacement has no universal rule. Political priorities, national security needs, industrial policy, and the missions assigned to a navy all shape the decision. A navy can also renew an existing class or continue producing a proven design with selected improvements. Germany's decision to build more of an established corvette design illustrates how continuity can preserve useful capability without paying to reinvent it. Novelty alone is not evidence that a new ship will be more useful, especially when a supposedly new programme recreates the general-purpose role of the class it displaced.
Chapter · 1:45-7:46
Replacement, renewal, or continued production
Replacing a class is not a binary choice: a navy can refit it, build more of a sound design, or begin a genuinely new class.