Why outside metalwork cannot fill a shipyard's order book

Why not keep shipyard workers occupied with side jobs in metalworking?

Shipyards already try, but relatively few outside projects need their specialized facilities or can bear their costs, so side work alone rarely employs everyone.

A shipyard can accept other metalworking contracts during gaps in hull construction. The difficulty is finding enough jobs that need the yard's capabilities and can pay the associated costs. Government subsidy is raised as one way to sustain work that would otherwise be uneconomic, while hull construction remains the activity most likely to occupy the full workforce. The historical comparison runs in the other direction: during the Second World War, bridgebuilding firms in places such as Wisconsin took up ship construction. Skills could transfer into shipbuilding without establishing that an idle shipyard could always replace its naval orders with outside work.