How small supply delays become major shipyard delays

Why can ships built at the same yard take very different times to complete?

Delays in critical components and crane availability cascade into later work, turning small interruptions into major schedule differences.

Shipyard completion times depend on chains of work rather than the hull alone. Engines, gearboxes, and other critical components have to arrive at the correct point in the construction sequence. A late item can block the crane lift that enables several later jobs, while the crane may be committed elsewhere by the time the component finally appears. Work that depended on that installation then moves out of sequence and encounters new competition for labour and equipment. Small supply interruptions can consequently compound into large differences between completion times at the same yard.