Why German naval industry never recovered before 1939

When did German naval infrastructure recover from the effects of the Treaty of Versailles?

It did not recover before the Second World War; rebuilding skilled labor and industrial practice required far longer than Plan Z allowed.

Germany's naval industrial base had not recovered by the outbreak of war. Three or four more years of sustained investment might have narrowed the gap, while inconsistent funding could have pushed recovery closer to a decade. Versailles-era disruption had removed a generation of skilled workers, and yards could not recreate that experience on the advertised Plan Z schedule. The United States faced its own shortage despite greater industrial potential, while Britain entered 1939 with the world's largest concentration of skilled shipyard labor. Physical yards without trained workers do not create immediate building capacity.