[denis_469]

And what about unpowered B7 A2 barges built by Concrete Ship Constructors of National City, California and launched in 1944?
http://www.concreteships.org/ships/barges/yogn82/

I think, that need olso

Or B7 D1 barge: http://www.concreteships.org/ships/barges/quartz/

All concrete