 | This article needs additional citations for verification .(June 2025) |
Special Hull Treatment was the process, devised in the 1980s, by which defense contractors coated the outsides of the hulls of submarines with a rubberized tile that was designed to deaden noise, redirect sound waves, and absorb or contain hull noise. [1]
The tiles, measuring about 12 inches square resemble an octopus tentacle. They are actually constructed in a quadrahedral formation, in which the bottom sides have an array of holes. The holes connect to a central port in the center of the tile. This port is where a vacuum source is applied to pull a vacuum once the hole tile has been laid on the hull and glued with an epoxy. The epoxy takes about 1 day to harden, after which the vacuum is removed to make sure the tile has a good seal indicated by the vacuum not dissipating.
The tiles' shape is like the facets of a diamond or gemstone. It has four angles, and the construction of the tile is a soft black rubber with lead shavings impregnated in it. Each tile is fitted on the hull, and a caulk is applied in the seams between the tiles. The hull has to be sandblasted to bare metal and then re-coated with a special paint. The epoxy is applied to that paint. During the process, the hull is maintained above the dewpoint and in a controlled environment so that condensation does not occur during the process.
The first sub to receive this hull treatment was the USS Batfish, c. 1980.