Technology: Seagoing Ice Plow

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To clear a path for commercial ship ping in the Arctic, conventional ice breakers ride up on the ice and break it downward. The technique has limitations. Forcing the ice down against water resistance reduces the efficiency of even the world's most powerful ice breakers. And broken chunks bob up astern, where they may damage cargo vessels that follow. Often the icebreakers are halted when pressure and friction from trapped floating chunks form a vise along their sides. Now a Canadian inventor, Scott Alexander, 55, has developed a new device that breaks ice upward. The new present seagoing ice plow, called the Alexbow, may well render present-day icebreakers obsolete.

Made of five-eighths-of-an-inch steel, the Alexbow's 14-ft.-high concave blade is attached to the nose of a tug-pushed barge. It glides under unbroken ice, exerts upward pressure. As the ice breaks, it rides up the slopes of the bow blade and is deposited on solid ice at either side of the barge.

Year-Round Passage. During its first full-scale tests on Lake Ontario, the Alexbow, attached to a 65-ft. barge pushed by a 1,320-h.p. tug, cleared a 30-ft. channel in unbroken blue ice 14 inches thick. It also knifed 180° turns as though the ice were butter. Running at speeds from 21 to 31 knots, the tug accelerated easily in thinner ice because there was no friction along the sides of the barge — the Alexbow had thrown all the troublesome chunks clear.

Since the trials, Alexander has refined his Alexbow. Pushed by a 2,500-h.p. tug, he says, it can now tackle ice from three to four feet thick. He also proposes a detachable version that could be fitted to any vessel, and a plow that could be built onto the bow of a ship during construction. "There is no question in my mind," he says, "that one day icebreakers will no longer be used. Cargo ships themselves will do the ice-breaking." In a prelude to such an era, two Alexbow-equipped barges will be driven by a 5,000-h.p. trawler through 200 miles of Arctic ice this summer to supply a consortium drilling for oil on Canada's northernmost islands.