Product: Concrete Submarines

Cheap and deadly, these stealthy boats could shift the balance of naval power.

Concrete submarines could be the dumbest idea in naval history. Or, they just might give poor nations a way to checkmate their richer, more technologically savvy foes.

Going to sea in what amounts to a hollow rock is actually a well-proven idea. Concrete ships carried cargo during both world wars. College kids hold an annual concrete canoe race. And you'll find concrete barges, houseboats and sailboats in scores of marinas.

Now the Russians want to take the idea to a new low--with concrete submarines. Called C-subs, these 6-man vessels will differ from today's submarines in several important ways. Conventional submarines float until they take on water. C-subs will stay afloat by using four electric turbine pumps to propel water downward. The swiveling nozzles that direct this flow also will enable the C-sub to move.

C-subs will also fight differently. Conventional submarines prowl the seas. On a typical patrol, a C-sub will sink offshore, waiting for enemy ships to pass overhead. Then it will fire vertical-launch torpedoes. Because concrete is strong in compression, C-subs could sink well below the 1800-ft. "crush depth" for steel, according to the British Ministry of Defense (MOD). And on sonar displays, the concrete will be hard to distinguish from a sandy sea bottom.

MOD knows about C-subs because they resemble an idea floated by German marine engineer Heinz Lipschutz in 1957. The Royal Navy wasn't interested then, but MOD thinks that the new Russian C-sub has a feature that poor countries will find hard to resist--rocket-powered torpedoes. Developed in the early 1990s and code-named Shkval--Russian for squall--they can travel through the water at 230 mph, about four times as fast as conventional torpedoes.

Shkval-launching C-subs could shift the balance of naval power, cautions British defense analyst Julian Nettlefold: "With these craft being potentially so cheap to make, there is the danger of countries such as Iran and Libya using them to threaten American carrier groups or to barricade certain ocean routes."