Turtle – America’s Revolutionary submarine

Submarines were first built by Dutch inventor Cornelius van Drebel in the early 17th century, but it was not until 150 years later that they were first used in naval combat.  David Bushnell, an American inventor, began building underwater mines while a student at Yale University. Deciding that a submarine would be the best means of delivering his mines in warfare, he built, along with his brother Ezra, an eight-foot-long wooden submersible that was christened the Turtle for its shape (Bushnell believed the craft resembled “two upper tortoise shells of equal size, joined together”). Large enough to accommodate one operator, the submarine was entirely hand-powered. Lead ballast kept the craft balanced.

There were many engineering and design problems, which he had to solve with the limited technology of that time-problems such as building a watertight, pressure-proof hull, providing for vertical and horizontal propulsion, vertical stability, variable ballast, steering controls, and a weapons-delivery system, to name a few. Bushnell eventually solved these problems and introduced some innovations. For example, he was the first submarine designer to equip such a vessel with a snorkel breathing device and to use a two-bladed propeller for ship propulsion.

She measured 7 feet in depth from the bottom of her detachable keep to the top of her upper “shell”, and was constructed of oak timbers, which were carefully shaped, joined together, and caulked at the joints. To insure watertightness, the vessel was bound with iron bands and entirely covered with pitch on the outside.

A little egg-shaped wooden submarine held together by iron straps, Turtle bobbed like a cork in rough surface winds and seas even though she was lead weighted at the bottom. In this hand- and foot-operated contraption, one person could descend by operating a valve to admit water into the ballast tank and ascend with the use of pumps to eject the water. Two flap-type air vents at the top opened when the hatch was clear of wafer and closed when it was as not. 

The submarine was capable of carrying one person who sat upright on a seat resembling that of a bicycle. Turtle’s supply of air, in the submerged state, would last about 30 minutes. Located at the bottom of the submarine were a lead weight for ballast and an aperture with a valve to admit water for descent. Two brass forcing pumps served to eject the water from within for ascent. In front of the seated operator was a screw type oar for propelling the vessel forward or backward while, above him, there was a similar oar for ascending, descending, or maintenance of depth. The rudder, located behind the operator, was operated by foot. Furthermore, Turtle was equipped with a depth gauge, a compass to direct the course, and a ventilator to supply the vessel with fresh air at the surface.

In the spring of 1776, Turtle was ready to be transported by a sloop to Boston to fight the British fleet. By that time, however, the news was received that the British had broken off their blockade there and had moved their ships north to Halifax, Nova Scotia. Since there were still British warships in New York Harbor, Turtle was secretly transported there and stationed at The Battery in Manhattan, which was still under the control of America’s General Putnam, with his army of about 9,000 men.

The waters of New York Harbor, between The Battery and Governor’s Island, had complex patterns of currents and tides, presenting navigational problems completely different from those in the Connecticut River. Ezra, who operated Turtle, trained through June, 1776 until he and David were satisfied that he was familiar with the tidal conditions. General Putnam gave them permission to attack the 64-gun British warship HMS Eagle at the first opportunity.

The opportunity presented itself on July 12 when Lord Howe, the commander of the British naval forces, anchored Eagle off Staten Island, but one adversity followed another. Ezra Bushnell became ill with fever and was unable to operate Turtle. Since General Putnam and George Washington agreed that the submarine should be tried against the enemy, Sergeant Ezra Lee of Old Lyme, Connecticut was selected from a group of volunteers to operate her. For the next two months, Ezra Lee trained intensively.

Near midnight of September 6, the moon and the tide were favorable for attack. Turtle was towed by a small rowboat toward Eagle. Halfway to Staten Island, the rowboat stopped, and Lee entered Turtle and fastened the hatch over his head. For the first time in the history of naval warfare, a submarine was engaged in a war against an enemy ship.

After diligent pedaling, Lee brought Turtle on the side of Eagle. After taking some ballast, he submerged completely. When he thought he was under his target, he pumped out a small quantity of water from the ballast tank, until a jarring bump indicated he was beneath Eagle. For the next few minutes, Lee vainly tried to attach a torpedo to her hull. When the air in his little cabin was almost used up, Lee had no choice but to abandon his attempt and surface. After replenishing the air in the cabin and resting, he again descended underneath Eagle to try to affix a torpedo on her hull. He failed. A metal plate covered the area where he was trying to drill. Having consumed his air, he was forced to abandon his goal and surface.

Lee was exhausted, and the outgoing tide threatened to take the small craft out to sea. Desperately, he ejected all the ballast water and began pedaling with all his remaining strength. With the ballast water pumped out, one third of Turtle’s hull stuck out of the water, making it clearly visible in daylight. In fact, as dawn broke, two British soldiers set out from Governor’s Island in a patrol skiff to investigate the floating object. To divert the patrol and to lighten his craft, Lee released a time operated 250-pound (113 Kilograms) torpedo and, picking up speed, reached the battery and safety.

Soon thereafter, the torpedo exploded, shattering the silence of the early morning and arousing the British fleet. Quickly, the British raised their anchors and hurriedly moved their ships to the safer waters of lower New York Bay.

Although Turtle’ s original mission was unsuccessful, some historians claim that the venture was not a complete failure. They suggest that the incident drove the British ships to a new location from which they could not maintain an effective blockade of New York. Also, although Turtle inflicted no damage to any British vessel, an intangible psychological victory might have been attained, simply through her use as a weapon.

Turtle was equally unsuccessful in two subsequent efforts against Eagle and another British frigate. In both instances, the tides and tricky currents of New York Harbor frustrated the ventures. In an effort to move the submarine to areas where attacks could occur under more favorable conditions, Bushnell loaded Turtle aboard a fast sloop, hoping that the sloop could slip unnoticed past the British into Long Island Sound and back to Connecticut. A British frigate discovered the sloop, however, and, according to the British, sank her and her precious cargo. The Americans claimed that she was dismantled and moved inland to keep her out of enemy hands. Whatever the final fate of Turtle, as the first American war submarine, she came to a premature end and closed a not-so-glorious chapter of maritime history in the American Revolution.

Despite the failures of the Turtle, General George Washington gave Bushnell a commission as an Army engineer, and the drifting mines he constructed destroyed the British frigate Cereberus and wreaked havoc against other British ships. After the war, he became commander of the U.S. Army Corps of Engineers stationed at West Point.

Although it did not achieve military success, Turtle was seen by men of the time as a revolutionary development. In 1785, George Washington wrote Thomas Jefferson: “I then thought, and still think, that it was an effort of genius.” The problem with Turtle, as the former head of the Naval Historical Center, Admiral Ernest M. Eller wrote, was Bushnell’s expectation that just one man could “carry out the combined duties of diving officer, navigator, torpedoman, and engineer, while at the same time fighting tides and currents and propelling the boat with his own muscles.”

The Turtle embodied the four basic requirements for a successful military submarine: the ability to submerge; the ability to maneuver under water; the ability to maintain an adequate air supply to support the operator of the craft; and the ability to carry out effective offensive operations against an enemy surface vessel.

To achieve these requirements, Bushnell devised a number of important innovations. Turtle was the first submersible to use water as ballast for submerging and raising the submarine. To maneuver under water, Turtle was the first submersible to use a screw propeller. Bushnell was also the first to equip a submersible with a breathing device. Finally, the weaponry of Turtle, which consisted of a “torpedo,” or mine that could be attached to the hull of the target ship, was innovative as well. Bushnell was the first to demonstrate that gunpowder could be exploded under water and his mine was the first “time bomb,” allowing the operator of the Turtle to attach the mine and then to retire a safe distance before it detonated.

While a submarine “practical” for warfare with range, power and reliability had to await the coming of the mechanical age, Turtle was an indispensable first step, which made future developments possible.