The diagram and the 19th-century engraving above show the Turtle’s basic components, as well as the position of the operator. It was a lot to hope for-as it turned out, perhaps too much. The mine would hopefully stay in place while the fuse burned down to the charge and exploded, leaving the enemy vessel with a hole blown in its hull. Bushnell’s idea was for the operator to navigate under an enemy ship, drill the screw into the hull, detach the entire assembly while setting the fuse-a clockwork device with up to a 12-hour delay-and make his getaway. The charge, consisting of 150 pounds of black powder, was designed to be buoyant, and fastened to the outer hull of the enemy ship by means of a detachable screw device. Attached to the screw was a waterproof fuse that led to the explosive charge. The Turtle’s crank handle operated an external screw system whose controls were located in the vessel’s upper chamber. Once the Turtle made its way to its target, the job was only half finished-the operator then had to deliver the ordnance. A decidedly uncomfortable feature of the seawater ballast system was the fact that the Turtle had no true ballast tanks the incoming seawater simply flooded the floor of the craft, leaving the operator knee-deep in water until it was eliminated with the pumps when it was time to surface. The ship dove and surfaced by means of brass pumps that took in or expelled seawater as ballast, as well as using 700 pounds of lead weights, increments of which could be played out on a 50-foot line and retracted as needed. The Turtle could float on the surface and pump in fresh air through a leak-proof intake valve, but once under water the operator could only keep the vessel below until the air ran out. Submerged, he made use of a compass lit by phosphorous. The operator determined where he was going while on the surface by looking through a set of glass ports surrounding the hatch. He steered by means of a rudder at the rear of the vessel. The operator entered through an airtight hatch on the top of the sub, sat on a traverse beam mounted inside the vessel, and drove the submersible with hand-cranked propellers, a large one in front and a smaller one on top. Measuring a mere 7 1/2 feet tall and six feet wide at its center, it was barely large enough for its single operator to squeeze inside. The Turtle was constructed of oak, covered with pine-tar pitch for waterproofing, and held together with iron bands. The hull of the vessel looked like two halves of a Turtle shell pressed together, hence its nickname. It looked more like a beer keg, with an oversized screw sticking out from the top, and its propellers and rudder oddly positioned on three different sides of the contraption. The Turtle bore almost no resemblance to the modern concept of a submarine. Bushnell lacked the physical strength and stamina to operate the vessel himself, so his brother Ezra volunteered for the job. The Turtle was born.ĭuring the Turtle’s initial trials in the relative safety of the rivers of Connecticut, another famous colonial inventor, Ben Franklin, was an admirer of the awkward-looking vessel, watching from shore as the Turtle was tested. For this purpose, Bushnell and Pratt developed a one-man, hand-propelled submersible vehicle to transport their bombs to an enemy vessel. The only dilemma facing the inventors was how to deliver the mines, or “time bombs,” to their intended target. The idea met with considerable skepticism as to whether gunpowder could be made to explode underwater, but Bushnell successfully proved that it could. One of the pair’s first concepts was an underwater bomb with a time-delayed flintlock detonator, a forerunner of modern naval mines. The powerful British Navy would have to be dealt with in order for the Revolution to be successful, and it was apparent that America’s fledgling navy would hard-pressed using conventional tactics. He was a fervent patriot who felt strongly that technology would be the key to winning the war, so he and fellow inventor and Yale intellectual Phineas Pratt set to work. At the relatively advanced age of 31, Bushnell elected to pursue a higher education and entered nearby Yale College to study mathematics.īushnell graduated from Yale in 1775, on the eve of the American Revolution. Bushnell’s father passed away when he was 29, and he eventually decided to sell the family farm. In fact, he was a farmer for most of his early life. Bushnell did not start his career as an inventor, engineer, or even as a seafarer. The revolutionary craft, known as the Turtle for its odd profile, was the progeny of David Bushnell, who was born in 1742 in West Saybrook, Conn. The world’s first combat submarine was something of an afterthought on the part of its creator.
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