Where concrete works in ship construction

How often was concrete used to build ships?

Mostly for simple barges, one-use craft, ballast, and emergency repairs rather than sophisticated reusable warships.

Concrete can float and can be mass-produced for simple purposes, yet it produces heavy, rudimentary hulls. It works best when a craft has a narrow or one-use mission, such as a barge or invasion unit. As an emergency repair, concrete can plug a hole or add weight where a damaged ship needs help regaining stability. That temporary patch may save the vessel, but a yard must later cut out the affected section and restore it properly. The material is therefore useful when speed, simplicity, or ballast value matters more than long-term performance and easy repair.