I recall reading about this contraption, and having a presentation (which I found at ndia.org in the proceedings section, early '2000s) showing impressive pics of this thing's forebearers in action destroying mines. Underwater!. I recall the munition used was a supercavitating thing that would lead to the development of AHSUM (Advanced High Speed Underwater Munitions, pronounced “Awesome”). Recommended: The Science of War-Weapons, Scientific American.com, special online issue no.1, 2002, article "SWIFT SUBSEA WEAPONS Warp Drive Underwater"