The first Turtle was designed in 1771 by David Bushnell, a Yale - TopicsExpress



          

The first Turtle was designed in 1771 by David Bushnell, a Yale student, and built with the help of his brother, Ezra Bushnell, in 1775 at Saybrook, Conn. The submersible was named Turtle because Bushnell thought that this unique craft bore some resemblance to two upper tortoise shells of equal size, joined together. Conceived as a means of breaking the British blockade of Boston harbor, the submersible embodied four basic requirements for a successful military submarine: the ability to (1) submerge, (2) to maneuver under water, (3) to maintain an adequate air supply to support the operator of the craft, and (4) to carry out effective offensive action against an enemy surface ship. Turtle could be made to submerge by simply flooding her bilges with sea water. To surface, the man operating the submarine would pump out the bilges. A crude conning tower, fitted with round, glass ports projected some six or seven inches above the surface of the water. This arrangement allowed the operator to see where he was going and permitted light to illuminate the equipment necessary to operate the submarine. When submerged, Turtle was illuminated by instruments made of a phosphorescent wood known as fox fire. Maneuverability in the horizontal plane was achieved by a hand- or foot-cranked propeller fitted at the bow. Ascent or descent was made possible by a second propeller fitted just ahead of the low conning tower arrangement. It was possible for Turtles operator to propel the craft forward by utilizing the foot-treadle to operate the bow propeller while simultaneously using the hand-operated second propeller to move the craft up or down. Steering was accomplished by a tiller. The combination of the crafts shape and the ballast load—700 pounds (500 fixed and 200 detachable)—gave Turtle a low center of gravity and made her quite stable. Air was supplied by a pair of tubes fitted through the conning tower hatch. Valves in these pipes would automatically shut them while the vessel was submerged. The tubes themselves actually resembled a crude snorkel arrangement. -Naval History & Heritage Command
Posted on: Thu, 05 Jun 2014 15:57:37 +0000

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