Supercavitation

Cavitation, as any old salt knows, is the bane of propellor-driven boats and ships. Props that run too fast cause "holes" to appear in the water and the result is both a decrease in efficiency and, in extreme cases, physical damage to the propellors as the cavities collapse with a "bang."

In the 1970s and 1980s, the Russian Research Institute of Applied Hydromechanics in Kiev developed a practical use for cavitation. Called supercavitation, it created a vapor-filled cavity around a torpedo that was so big that the water no longer touched the torpedo body. The result was a rocket-powered torpedo called the VA-111 Shkval, capable of speeds above 200 knots (230 mph.) They produced quit a few and actually sold about 60 of them to China in the 1990's. Unfortunately, the Shkval was a "strait-shooter," meaning the Russians had not found a way to manuver the torpedo without destroying the cavity.

The US Navy has belatedly started work at ONR to find ways to use and to defend against supercavitation weapons. Theoretically, small vehicles can travel at speeds up to 600 MPH and submarine-sized vehicles can travel at speeds of 100 mph.

Needless to day, such weapons are super secret. Nobody is willing to talk about how they might be deployed and what defenses are possible. One obvious way is to use ship-ro-surface missles which themselves supercavitate, but detection and tracking, not to mention guidance, are left as "an exercise to the student."

The problem is especially acute given our current dependence on "conventional" nuclear aircraft carriers and submarines. The USS George H. W. Bush (CVN 77), commissioned in January, is the last of the Numitz-class carriers to be built. But the next generation of carriers, beginning with the USS Gerald Ford (CVN 78) is well into design and the keel has been laid. It's not stealthy; it's built on a hull about the same size and shape as the Nimitz class. It's due for delivery in 2015.