Speed Through a Straw

For more than three months, H.M.S. Highburton plowed endlessly back and forth over a measured mile in choppy waters between the southern coast of England and the Isle of Wight. It was a monotonous mission for the crew of the coastal mine sweeper, but it may well prove momentous for the commercial fleets and navies of the world. During those test runs, the British Admiralty said last week, a versatile chemical helped the little ship to cut its normal fuel consumption by 15% and to reach speeds higher than it had ever before attained.

As it nosed through the water, the Highburton intermittently spewed a dilute solution of water and polyethylene oxide through vertical slots near its bow. As the solution washed back, it lubricated the hull, reducing friction between the water and the moving ship by about 20%. Thus less power was needed for driving the ship forward, fuel requirements were reduced, and speed increased.

Polyethylene oxide, the material that eased Highburton's passage, is known to chemists as a long-chain polymer because it consists of lengthy strings of linked molecules. In the water near a ship, the molecular chains act much like an array of thin parallel tubes, allowing water to flow smoothly back along the hull but retarding its movement in any other direction. As a result, the friction-building turbulence that is normally generated by a ship slicing through the water is sharply reduced.

The lubricating effect of long-chain polymers is also being studied in the U.S. In Dallas and Cleveland, the chemicals have been injected into sewer lines to speed the flow of wastes and thus increase the capacity of the disposal system. Dallas has reported a 2.5-fold increase in flow through a test line. California's TRW Systems has received a Navy contract to investigate the possibility of using long-chain polymers to make torpedoes run faster.

Before approving the use of polymers on its ships, the British Admiralty is investigating the possible pollution hazard of polyethylene oxide. Tests are under way to determine if the chemical is harmful to marine life, and whether it will accumulate near the surface or eventually decompose and dissipate in sea water. There is apparently no question, however, about the effectiveness of polymers in increasing a ship's speed. Their use has been banned by England's Amateur Rowing Association.

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