In marine salvage involving the raising of sunken ships, or the dewatering of stranded ships which are bilged, one of the principal problems which the salvor faces is that of gaining buoyancy. He may do this by adding external buoyancy, or the salvor may prefer, for reasons of logistics or engineering, to apply internal buoyancy in the ship. This he may do by merely pumping out the compartment if this is possible; or by displacing water in the compartment with compressed air (i.e. blowing down); or by the insertion of buoyant materials to displace the water. The pumping or air blowing methods are the standard techniques of the salvor, however, in frequent salvage cases these standard techniques can not be used at all or are not sufficient to save the ship. It is in such cases that the application of buoyancy material into the ship is necessary or, at least, cost effective. What is novel and unique about an internal buoyancy system is the concept of obtaining lift by injecting a liquid polymer system into flooded spaces, expanding-in-place to many times its original volume, and displacing water. The past several years have seen the development of at least two significant cellular plastic systems for the introduction of internal buoyancy, underwater, as a tool for the salvor. One of the systems, called Foam-In-Salvage (FIS), is a cast-in-place urethane foam technique. The other system which is referred to as EPS involves the use of Expandable Polystyrene beads which are pumped in a water slurry into the flooded ship. The latter system was developed into a practical ship salvage technique in 1964-1965 by the firm of Karl Kroyer, Inc. of Denmark. Both systems have already been successfully used on a number of salvage operations. This paper first reviews the major salvage operations in which the FIS and EPS internal buoyancy systems have been employed and second, addresses the technology involved. An FIS system operational to an ocean depth of 200 feet is presented and a possible technique for extending FIS depth capability to 450 feet is described. Successful salvage recoveries of sunken vessels involving the use of plastic foam systems are also described.

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    American Society of Naval Engineers

    Suite 507, 1012 14th Street, NW
    Washington, DC  United States  20005
  • Publication Date: 1970-8

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  • Accession Number: 00019341
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 8 1971 12:00AM