Palatka, Fla. shipbuilder St. Johns Ship Building announced it has signed a contract to construct a pair of 80 x 54 x 12 spud barges for marine equipment company Mobro Marine, based in Green Cove Springs, Fla.The spud barges, built to support various marine construction and operations, will join Mobro Marine's fleet serving across the Atlantic Ocean, Gulf of Mexico and the Caribbean.“Having St.