Air-Lubricated Ships Blow Bubbles out the Bottom

This is NOT supercavitation.

While superficially similar, supercavitation refers to the lowering of water pressure surrounding a submerged body to below vapor pressure, by means of the Bernoulli's principle. By such the object is actually traveling through water vapor instead of water, greatly reducing drag.

I was just going to say that this is done on some experimental subs and torpedos for increased speed, but since that's already been mentioned I'll say that there are some airplanes that do something analogous, but they do it to control laminar flow. It was quite costly to build but radically increased the efficiency of the plane by reducing drag.

Vikings invented this for few hundred years back.

I remember seeing this back in the 90's or so as a way to defeat sonar. The bubbles created a sort of static that on sonar sounded like waves on the surface. A sonar ping would not bounce too well off of the bubbles. It gets thrown around. From what I remember reading the idea never really went anywhere because producing the bubbles in such a way that the entire hull was covered was very hard and the ocean did not treat the equipment very well. It would have been a nightmare to maintain. So 20 years later they may have better technology to do this.

if this catches on, they'll have to make larger bathtubs.

Supercavitation.. been theorized in submarines for a while and iirc its used for some torpedos

There was a speed boat designed once with the same concept. I'd appreciate anyone that can find it, if memory serves it used a flat bottom with vents cut to direct air beneath it at speed.

There are obvious human applications to this concept.

Heh. For the same reasons, my uncle has done this for years.