Shipping Out with Superconductivity

It wasn t really a ship, this crudely shaped hull resting on blocks in a dusty laboratory storeroom at the University of Mercantile Marine in Kobe, Japan. Just a 12-foot, wooden-hulled model that looked as if it had been knocked together out of spare parts by a steam-fitter working from blueprints for an antiquated carnival ride. 

It had no engine, no propellers, and no rudder, and its top speed, during its brief shakedown cruise in a tank full of salt water, was only 1.5 knots, which left a wake that even a duck wouldn t be proud of. But, shrugged its developer, physicist Yoshiro Saji, it moves, and that s a beginning.  

There are two concepts Saji s, and one the U.S. Navy has been interested in since 1969 or so. Both rely on superconductivity, but they work in totally different ways. 

The same thing happens in Saji s magnetic ship. It is, in effect, an ingenious version of what is essentially a DC motor. Except that there is no motor and no rotor. Indeed, it has no moving parts at all. Instead of wire, the conductor 

The Japanese Magship, shown here in a cutaway drawing, is propelled by magnetic thrust that relies on the principle of magnetic repulsion. In this instance, between the field from an onboard magnet and an electric current in the sea. 

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