I believe that this technology may be used in some torpedoes. The Russians have apparently taken this idea to the limit with a torpedo that has a small rocket engine pointed _fowards_ (!) The idea is to generate enough gas ahead of the torpedo so that the torpedo is more-or-less travelling through the gas instead of the water. Such torpedoes can apparently reach very high speeds. There have been rumors that the Kursk was testing such a torpedo when one exploded while still inside & the sub sank: http://en.wikipedia.org/wiki/Russian_submarine_Kursk_(K-141) At 02:03 PM 1/18/2014, Warren D Smith wrote:
It has been found that by making your boat have a rough surface made of "ultra hydrophobic" substance, drag can be reduced versus a usual smooth surface. Air bubbles are trapped in valleys on the surface and so instead of water obeying usual "no slip condition" at solid surface, they contact an air bubble surface instead. The air acts kind of like a lubricant between the boat and the water.
Sounds like a very promising idea.