Less than two centuries mediate between the humble Turtle, sort of wooden barrel propelled by cranks, and the Thomas Jefferson, first nuclear ballistic submarine and exponent of the most destructive type of weapon ever deployed.

During the 19th century a good number of inventors from several countries tried to take advantage of all the technical progress achieved during the industrial revolution. What during former centuries seemed an impossible quest was becoming more and more feasible for the new generations of engineers, and at the end of the century several models existed which were able to transport their own engine and armament.

Not much later, during the First World War, it was finally seen the effectiveness of the submarine weapon and the dramatic consequences that it brought, represented by several millions of tonnes of merchant ships sunk during the two world wars. The promising qualities of the submarine weapon suffered a momentaneous drawback during the second half of the Second World War, but the technical advances applied during the immediate postwar years returned the submarine weapon to its former status quo.

The dramatic characteristics that have been inherent of the submarine weapon already from its inception (stealth attack, devastating underwater shockwave and a prominent danger for the own crews) were greatly emphasized by the apparition of submarines capable of remaining submerged during months and launching an array of intercontinental ballistic missiles from beneath the waters. To achieve this, also the size of the submarines had to grow dramatically.

Evolution of submarines

The Turtle: first submersible vessel

The first military operation performed by means of a submersible vessel has been credited to the contraption created by David Bushnell in 1775, called "Turtle", and happened in the context of the American War of Independence. In the night of the 6th September 1776, Sergeant Ezra Lee of the United States departed onboard the Turtle to approach the HMS Eagle, a third-rate ship of the line of the Royal Navy anchored in the port of New York, with the purpose of sinking it. Due to the obvious limitations of Bushnell's submersible vessel this had to be a difficult mission; and indeed, difficulties soon arose.

Once the tugboats released the Turtle, the strong water flow pushed the tiny vessel far from the HMS Eagle, and as a result Lee had to turn the cranks during two hours until reaching the enemy flagship. The planned procedure was to place the Turtle just beneath the hull of the HMS Eagle, to drill a hole on it to attach the clockwork bomb that the Turtle carried in a box attached to her wooden body. Like many other warships of those years the HMS Eagle had her underwater body lined with copper sheets to prevent Teredo worms from making holes on it. Because of this, or more probably because of the very poor stability of the Turtle, another difficulty arose.

Regardless of his efforts, Lee could not pierce the hull, so he had to abort the mission and escape. But troubles would not end there, for the Turtle was detected and thereafter chased by rowing boats, which would have no difficulty in catching a barrel-like vessel propelled by rudimentary screws attached to manually operated cranks. Lee had to play the only card available to him in that troubled moment, so he released the bomb hoping that an explosion in the water would neutralize or disband his persecutors; these, who were not fools, intuited the trick and gave up on the chase.

Turtle submarine, 1776
Inspection Window

From the "Turtle" to the "Fish-like"

Influenced by the design of the Turtle, several submersible models were developed during the first half of the 19th century. But as their predecessor, these were largely rudimentary contraptions that achieved little success. The hulls of the new models had an elongated shape to increase the hydrodynamical efficiency and, when the budget allowed it, they were built of metal instead of wood. Propulsion was achieved through manually-operated cranks, sometimes associated to gear sets, and the model built by Robert Fulton in 1800, in the late stages of the Age of Sail, had a removable rigging as well. Fulton built a copper hull which had a ballast tank in its lower part to enable it to submerge into and emerge from the sea. He tested his vessel in the Seine river in an attempt to elicit the interest of Napoleon, but the Emperor showed no enthusiasm for the idea.

Fulton's Nautilus submarine, 1800
German inventor Wilhelm Bauer built in Kiel, in 1850, a strange 8-meter long vessel which was manned by a crew of three: one for steering the rudder (Bauer himself) and two for rotating the propeller. The hull had the shape of a rough ship with rect ends and it was coated with iron sheets. Ballast water was admitted directly into the hull and a sliding weight, which moved horizontally along the hull's centerline, was used to control the balance of the vessel, as later hydroplanes would do. After a successful first immersion, in a second attempt the sides of the hull were crushed by underwater pressure and the crewmen narrowly saved their lives. So, this submersible vessel could never fulfill the purpose of attacking the Danish fleet which blocked the German ports.

Plongeur Marin submarine, 1850
With his second "Ictíneo" (Fish-like), in 1864 Spanish inventor Narcís Monturiol was ahead of his time. Three years before he had built his first "Ictíneo", which used manual propulsion. The new vessel had a double hull of modern shape, built of wood and coated externally with copper sheets; the ballast tanks located between both hulls could be pumped out by means of compressed air. Propulsion was made through a steam engine, even during immersion, when oxygen provided by a special device replaced the atmospheric air. The oxygen was stored in tanks and used as well for crew's breathing and for the internal lighting. The hull had portholes in the small turret, in the sides and in the bow. The purpose of this submarine was the harvesting of coral under safer conditions, but financial problems led to the scraping of this remarkable vessel in 1868.

Ictineo II submarine, 1864

The submersible vessel in the American Civil War

During the American Civil War, the Confederate States were facing the blockade imposed by the numerically superior Union Navy. For solving this situation their engineers resorted to unorthodox ideas such as the coarse armored ship CSS Virginia or the submersible boats presented in this article. The CSS David was the first submersible boat deployed in war actions as well as the first one propelled by a steam engine. This vessel was capable of navigating with the hull wholly submerged, protruding from the surface only the funnel and the small superstructure. However, steam propulsion had the obvious drawback of a clearly visible smoke trail.

The armament, and explosive charge attached to a long pole fixed to the prow of the vessel, was not wisely designed, as it potentially caused severe damage to the attacking boat as well. The capsule contained 60 kilograms of powder and a chemical detonator triggered by impact. The 5th October 1863 the CSS David attacked the ironclad USS Ironsides with this explosive charge, opening a large breach on her hull which however was insufficient to sink the ship. On the other hand, the small submersible took the worst part, as the explosion fatally damaged the vessel and the largest part of the crew died.

CSS David and CSS Hunley submersible boats, 1863-1864
One year later a new submersible boat, designed by Horace L. Hunley, was ready for trials. This nefarious contraption sank twice during the trials, causing the death of the largest part of the occupants, including Hunley. Once retrieved from the waters, the vessel was named after her infortunate creator. The CSS Hunley was propelled by the manual force applied by eight men; despite being slower, the new submersible would be at least more discrete and also smaller. The watertight metallic hull was designed for allowing a full immersion and two hydroplanes located in the prow allowed underwater diving and climbing. Oxygen inside the hull could last for two or three hours and the effort of manually propelling the boat greatly contributed to its rapid consumption.

The tragedy of the CSS David led to the adoption of a new attack method in which the explosive charge was not detonated by impact. The charge had to be placed on the target vessel and then detonated from a safe distance by means of a cable. The 17th February 1864 the CSS Hunley became the first submersible boat which managed to sink a surface ship: the steam-powered sloop-of-war USS Housatonic. However, this victory was tarnished by fatality as well, as the CSS Hunley was sunk as well and her whole crew perished; for some reason, the infortunate vessel was too close when the charge exploded. When after some years the remains of the USS Housatonic were examined, the CSS Hunley was found lying on the seabed with nine skeletons inside.

USS Intelligent Whale submersible boat, 1863
The USS Intelligent Whale was the Yankee response to the CSS David, first submersible vessel launched by the Confederate. This experimental vessel, manually propelled like the CSS Hunley, was hardly maneuverable and lacked an effective armament. Because of this, but mainly due to legal issues, she did not take part in any military action during the war. Immersion was achieved by filling water compartments, which for emersion had to be emptied by means of manual pumps or compressed air. It was estimated that the crew - a minimum of six for operating the vessel - could stay submerged for about ten hours.

During the only known trial, held in 1872 and reported by submarine pioneer John Philip Holland, two men commanded by a certain General Sweeney submerged the boat in 16 feet of water; then, wearing a diver's suit, Sweeney emerged through a hatch in the bottom of the hull to place an explosive charge under a scow. After returning to the submersible boat, the charge was exploded by means of a lanyard and a friction primer. This procedure required that, once reaching the target area, two anchors were released to keep the submersible boat in place. Then, compressed air had to be released until the pressure inside the hull were higher than outer's water pressure; this allowed to open the floor hatch without permitting water to enter.

~ History of the submarine weapon (II) ~

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