The invention relates to a marine vessel, such as ships, floating platform etc, where the whole or part(s) comprises a layered structure and a layered structure for use in vessels, including two substantially parallel metal sheets with a concrete layer in between, where the concrete has density significantly less than that of normal concrete, preferably less than about 1200 kg/m3, where the layered structure is dimensioned as if the concrete layer in the structure carries essentially no tension but is capable of carrying compressive forces and support the metal sheets. The invention also regards a method for improving carrying capacity at existing structures, and an improved corrugated structure. The invention also includes a layered structure module, elements for building a module, and methods for producing a layered structure according to the invention.