Abstract: The present invention is concerned with methods of and apparatus for constructing cylindrical structures such as large-diameter pipes for the transport of materials in ocean mining and the like, whereby one or more rolls of previously prepared sheet materials are wound around a core in a cross-wise fashion and bonded and treated by chemical and physical processes from a special floating platform that enables such construction operation in situ on the high seas.

Abstract: Underwater mining apparatus employs a rotatable drum having a plurality of rows of digging forks and a plurality of adjacent rows of openings for receiving materials loosened by the forks during rotation of the drum over the ocean bottom. The spacing between the forks determines the minimum size of material to be mined and the size of the openings determines the maximum size. A material-receiving trough extends longitudinally along the interior of the drum and communicates with the openings. A longitudinally extending spiral screw rotates with the drum within the trough to concentrate the material and to move the material longitudinally to a pick-up region, from which the material is transported hydraulically.