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Copper sheets stop nasty marine borers

Jan 1, 2003

Perhaps the ultimate in anti-fouling was discovered in the age of Sail: copper plating. Not only were the copper sheets effective at repelling barnacles and teredo worms, but they also apparently foiled the world's first submarine attack against a surface ship.

America's first attack submarine was designed and constructed by a Yale graduate, David Bushnell (1742-1824), for the express purpose of sinking blockading British ships during the early years of the American Revolution.

Bushnell's creation, Turtle, having a hull looking very much like two large turtle shells fused together, was seven feet deep and almost six feet wide and could be operated by one determined man. The operator guided the vessel using two hand cranks, one for propelling the vessel forward or in reverse, and a second for raising and lowering the vessel in conjunction with a foot-operated ballasting system. Steering was accomplished by a tiller/rudder combination, presumably held in the busy operator's teeth.

In a dead calm with the captain/navigator/galley slave frantically cranking and pumping, Turtle could attain a speed of three knots and dive to 20 feet for up to half an hour before the operator would be forced to the surface, gasping for air. Armament consisted of 150 pounds of musket powder in a mine-like package that was to be attached to the enemy's hull underwater by an auger. Ignition of this device was to be accomplished by a clockwork timer fuse designed to give the operator time, assuming he had any strength remaining, to beat a less-than-hasty retreat.In 1776, Bushnell enlisted Ezra Lee, a sergeant in Washington's Continental Army, to pilot the strange craft. Lee must have been a fine physical specimen with the tremendous stamina, courage, and above-average motor skills needed to drive the little submersible. The target chosen was British Admiral Richard Howe's flagship, HMS Eagle, moored in New York harbor.With great physical effort, Lee managed to maneuver Turtle under Howe's vessel but failed to deploy the mine because Eagle's bottom was covered with anti-fouling copper plates that prevented the auger attachment from taking hold. Evidently the copper cladding on Eagle's hull was effective in keeping out all types of marine borers.

After two additional failed attempts at mining enemy vessels, Bushnell abandoned his project, changed his name, and moved to Virginia, where he set up a medical practice.

contributed by J. Gregory Dill