what are the materials used in ship structures and construction?
['Steel: This is a highly versatile ship construction material and is used extensively on ships for the making of its integral structure and parts. ... ', 'Aluminium Alloys: ... ', 'The Shell Plating: ... ', 'Insulation: ... ', 'Superstructures: ... ', 'Watertight Doors: ... ', 'The Stern Frame: ... ', 'Rudder Pintles:']