A method and apparatus for replicating the submerged surfaces of ships and other marine structures. One apparatus includes a housing which is partitioned into forward and rear chambers by a membrane and a piston member, which is carried by the membrane. Upon selective flooding of the rear chamber and evacuation of the forward chamber, the piston member is moved toward the submerged surface to form an evacuated molding region therebetween. Liquid molding material is then drawn into the evacuated molding region and the molding device is retained in position until the material solidifies.
An alternative molding apparatus includes a housing with peripheral suction elements for releasably securing the housing to the submerged surface so that a molding region is defined therebetween. Upon displacement of water from and subsequent evacuation of the molding region, settable molding material is introduced into the molding region.