We are searching data for your request:
Upon completion, a link will appear to access the found materials.
Submarine – The History of Submarine War
The legendary origins of the submarine stretch back to 332 BC with a tale about Alexander the Great being lowered into the sea in a glass barrel to study fish. The submarine concept was thereafter consigned to the backwaters of history for some 1,800 years.
It reappears with the publication in 1578 of Inventions or Devises by William Bourne, an English gunner turned innkeeper and mathematician. In this work, Bourne describes the principle of making a boat sink and rise again by changing the volume of the ship. If you contract the volume of the ship, it will sink if you expand its volume, it will float upward. The exact process for doing this is not made clear, and contemporary materials and techniques precluded effective experiment.
The Alexander legend and Bourne’s principle related more to the diving bell than a boat. The next step forward, conceptually, was to add some form of propulsion. The Dutchman Cornelius van Drebbel achieved this around 1620.
His boat, Drebbel I, is probably the first working submarine. Basically an enclosed rowboat manned by 12 oarsmen, it probably had a sloping foredeck. This would have forced the boat under as forward momentum was applied, like the angled plane of a modern submarine.
In 1636, a French priest, Marin Mersenne, added another piece to the jigsaw. He suggested that a submarine should be built of copper and be cylindrical in shape to better withstand increasing pressure at depth. Early designs for submarines, henceforth, generally adopted a porpoise-like form. Despite these early concepts and the Drebbel I prototype, it was more than 200 years before the French Navy launched the first true precursor of the modern submarine. In 1863, the Plongeur (‘Diver’), which was powered by engines run on compressed air, became the first submarine that did not rely on human propulsion for momentum.
Military possibilities of the Submarine
It was not long before the military possibilities of a submerged boat began to be realised. As early as the First Anglo-Dutch War (1652- 1654), Louis de Son had built his 72ft-long ‘Rotterdam Boat’. This, in effect, was a semi-submerged battering-ram designed to approach an enemy warship unnoticed and punch a hole in its side. Once launched, though, it was unable to move.
The American War of Independence provided further impetus in the form of David Bushnell’s Turtle. Water was pumped in and out of the skin of the boat to change its ballast, thus enabling the boat to sink and rise. This one-man boat was driven by hand-cranked propellers, one to provide vertical movement and another to provide horizontal drive. The Turtle became the first submarine to attack a ship, probably the HMS Eagle, in New York harbour in 1776. The attack failed, as Ezra Lee, the boat’s pilot, was unable to attach its armament, a 150lb-keg of gunpowder, to the enemy ship’s hull.
Another American, Robert Fulton, attracted the attention of Napoleon in 1800 with his Nautilus. This submarine had a number of successful test dives, reaching a depth of 25ft and an underwater speed of 4 knots. It was driven by a hand-cranked propeller underwater, and by a sail when on the surface. Although it made a number of attacks on Royal Navy ships, they could always see the Nautilus coming and easily evaded it.
Failure meant Fulton’s dismissal, and the Royal Navy, with the world’s largest fleet, breathed a sigh of relief. Submarine warfare did not develop further for 50 years. Then, the American Civil War (1861-1865) provided a major stimulus, particularly on the Confederate side. The Union had retained control of the US Navy, and its blockade of the South meant that the Confederacy was bound to search for ways to break it: the submarine was one of these.
Several prototypes were built – by both sides – but these depended primarily on improvements to established technology rather than anything radically new. The most significant achievement was the destruction of the USS Housatonic in 1864, the first submarine victory. The oar-propelled CSS Hunley attacked the Housatonic with an explosive device on the end of a spar that was attached to its nose. Though the Hunley did not survive the attack, war beneath the waves had definitely begun.
The Royal Navy and the modern submarine
The real breakthrough, and the birth of the modern submarine, came courtesy of John Phillip Holland, towards the end of the 19th century. He became the first designer to successfully unite three new pieces of technology – the electric motor, the electric battery, and the internal combustion engine – to create the first recognisably modern submarine.
The Admiralty’s official position at the time was to give submarine development ‘no encouragement’. But it could not afford to ignore it completely, and, in October 1900, five Hollands were ordered with the purpose of testing ‘the value of the submarine in the hands of our enemy’. The Hollands were built under licence at Vickers’ yards in Barrow, which was to become the home of British submarine construction.
The traditionalist view at the Admiralty thought of submarine warfare, in the words of Rear Admiral Wilson, as ‘underhand, unfair, and damned un-English’. Notwithstanding such views, the submarine gained a champion in Admiral ‘Jacky’ Fisher. Having watched the five Hollands ‘sink’ four warships in an exercise to defend Portsmouth Harbour, Fisher realised that naval warfare had changed. So, when he became First Sea Lord (1904-1910), he diverted 5% of the Navy’s shipbuilding budget, despite strong opposition, to the construction of submarines.
From the beginning of Fisher’s tenure to the outbreak of the First World War, there was continual development of the submarine, from the Hollands through A to D classes. The D-class, with its decking and deck gun, represented a major change from the porpoise shape of earlier submarines, and introduced the form that would become familiar through two world wars.
Submarines in World War Two
Lulled into the belief that ASDIC made submarines irrelevant, the British Government, advised by the Admiralty, agreed in 1935 that the German Navy should be allowed the same tonnage of submarines as the Royal Navy.
Captain, later Admiral, Dönitz was ready with his submarine strategy. WWI experience implied that in a ‘tonnage war’, merchant ships could be sunk faster than they could be replaced. In order to achieve this, U-boats were to operate in Atlantic waters in ‘wolf packs’: seven or eight boats would shadow merchantmen across the sea, attack at night, and then submerge to escape, ready for the next attack.
The strategy worked until mid-1943, when the Germans had lost 250 submarines and sunk over 3,000 Allied vessels. In May, the tide turned, with 42 U-boats sunk in that month alone, forcing Dönitz to withdraw his fleet from the Atlantic. Even so, over the next two years they lost a further 520 submarines and sank only 200 ships. American aid, the convoy system, long-range air cover, and improvements in detection and anti-submarine weapons all had their effect.
Having lost the Battle of the Atlantic, the Germans were forced to rethink. One result was the development of the snorkel, a breathing tube that meant the submarine could use its diesel engine whilst just below the surface, conserving battery power. It also made submarines less visible from the air, though the snorkel did leave a trailing wake, and it could be picked up on sonar. The standard U-boat had been the Type VII, of which more than 700 were built. They were around 200ft long, with a surface displacement of 760 tons, and a surface speed of 15 knots, equalling the speed of most surface ships. They had a dive time of 20 seconds to a maximum safe depth of 650ft, a range of over 8,700 miles, and could go seven or eight weeks without refuelling. Britain’s equivalent workhorse was the T-class.
They were the first of the Navy’s boats to have their fuel tanks inside the hull, eradicating the problem of leaking fuel leaving surface trails. Whilst slightly smaller than the classes they replaced, they were an all-round improvement, and an all-welded hull meant they were stronger and able to dive deeper.
The T-class performed sterling service in all naval theatres of war. HMS Truant, for example, sank enemy ships in home waters, in the Mediterranean, and in the Far East – clocking up 81,000 tonnes of destruction in all. There was also success in the Far East for HMS Trenchant, which sank the Japanese heavy cruiser Ashigara.
Submarines during The Cold War
Post WWII developments were dominated by the Cold War and the arms race between the US and the USSR. Changed political realities meant a different role for the submarine. The Royal Navy’s job ceased to be aimed at attacking surface shipping, and focused instead on the interception of Soviet submarines.
The new Amphion class had been designed and introduced towards the end of WWII, but the submarine’s new role, and the development of increasingly sophisticated equipment, meant they were gradually refitted. They had already been given the Snort mast, a development of the German snorkel, and air-warning radar that worked whilst the submarine was underwater. Extra streamlining was introduced, which included the removal of the deck-gun but perhaps the most important advances were in the complex array of sonar devices that were added to the boat.
The Americans had also been busy, and another German invention, the rocket, became one of the major areas of advance in submarine design. The US’s experimentation with sub-launched missiles would lead to Polaris and Trident.
They also went nuclear in the sense of having developed a suitable power-plant for a submarine. In 1955, USS Nautilus made the first nuclear-powered submarine patrol, all 323ft and 3,674 tons of it. It had a surface speed of 18 knots and a capability of reaching 23 knots submerged. The Nautilus also represented a radical shift in design. Capable of sustained underwater cruising, the Nautilus had returned to the streamlined, porpoise shape of the early pioneers, for there was now no need to spend long periods on the surface. It revolutionised naval warfare, for it combined the stealth and surprise of traditional submarines with a speed greater than their quarry.
The British, too, developed nuclear-powered submarines, and Dreadnought, the Navy’s first example, went to sea in 1963. There were two strands to British design: one was the attack submarine, with responsibility for protecting Britain’s nuclear deterrent the other was the Submerged Ship Ballistic Nuclear (SSBN), which carried Britain’s nuclear deterrent. The most famous of the latter was the Resolution Class HMS Conqueror, which sank the Belgrano during the Falklands War in 1982, and remains the only nuclear submarine with an official kill.
Such combined operations point the way to contemporary military strategy. As the Malta Convention of 1998 declared the Cold War over, so the role of the submarine has changed. It is no longer just anti-submarine work, but, in military terminology, ‘Maritime Contributions to Joint Operations’. This also includes the ability to launch special forces operations and undertake intelligence gathering – but the Silent Service has always been capable of multi-tasking. Silent, submerged, and lethal, the submarine has changed the face of naval warfare.
Long ago I read a book "Undersea Victory: The Influence of Submarine Operations on the War in the Pacific" by Wilfred J. Holmes, but it was in Russian translation and I'm unable to find its available English version now. So there may be some discrepancies because of re-translation.
The author himself was a pretty distinguished submarine officer of the US Navy, with enough authority to regard his opinion as significant.
In the book there are first two chapters, which were written in style of novel and cover the first missions of the USS Gudgeon and USS S-38 in December 1941-January 1942, and they give some impression about everyday life on board of a submarine during the war, while the submarine was on a combat mission.
I don't remember all the details in the book, but there are some quotations I was able to find in a minute, which pertain to the subject (note, this is a re-translation from Russian):
In the high seas a submarine must be ready for an emergency dive in case of any surprise. All the hatches on the deck, except the conning tower one, must be closed and tightly battened down until a moment, when the mission was over and the Gudgeon, while returning to her base, passed that entrance buoy in the fairway [the author is describing a moment, when the Gudgeon was leaving the Pearl Harbor naval base and is talking about a buoy which seems to be marking the entrance to the base or something like that — my note]. After the submarine was ready for a dive, she and everyone, who was on her board, became as if an autonomous particle, separated from the world.
I suppose this corroborates the opinion that there usually were no leisure sun-basking or fresh air breathing sessions on the deck.
And this was true even for subs, which patrolled Japan's coast and were based at Pearl Harbor, even during their voyage from Hawaii to Japan and back, because of many dangers: enemy surface ships, submarines, but especially aircraft, as Holmes describes:
During several days the submarine could move on the surface both at night and day, without exposure to significant danger and incessantly closing on a remote combat zone designated to her but as she closed to the Japanese waters, surely it would be necessary to exercise more caution. The Gudgeon crossed the time demarcation line and entered the Eastern hemisphere.
As she entered waters in the 500-mile radius of the Japanese air base, she, in accordance with an order of the Commander of the Submarine forces [I'm not sure, if the title was back-translated correctly — my note], had to dive at dawn and move submerged until the full darkness, so that the enemy could not spot her. It was believed, that Marcus island, located at 1000-mile distance from Japan, was a Japanese naval air base. In order to reach the designated zone of patrol, the Gudgeon had to move 1500 miles through the waters, above which Japanese aircraft were patrolling.
Regarding life of board a submarine, there are several other excerpts, which touch many aspects, but no one mentions any crew members on the deck "to stretch their legs and get some fresh air", as was asked in the referenced question:
The routine of submerged move during day time exhausted the crew.
… The crew was divided to three shifts: one was being on duty, while the two others relaxed, made small repairs, tuned torpedo mechanisms, read or worked with documents.
… The radar, water-distiller and air-conditioning system — were three big advantages of the American submarines, but the Gudgeon was dispensing with the first two.
With the air-conditioning life was acceptable on board of the boat. On older submarines, without the conditioning system, heat and humidity, as the boat was submerged during all day, exhausted the crew, slacked them and caused skin diseases. As soon as the Gudgeon surfaced and her engines cooled, the air-conditioning system, which regulated temperature and humidity in the range most comfortable for a human body, started to work. On board there were chemicals to remove CO₂ from the air … Nevertheless, when the day ended, it had become pretty stuffy in the compartments and when the boat surfaced, fresh was meaning for men the same, as a drink of cool water for one suffering from thirst. Air pressure increased during the day, but it was possible to decrease it with an air-compressor. Still in certain cases the crew tried to avoid its use, since it created high noise.
I think, this answers the question to a certain extent. I cannot recall now an example pertaining to other periods of the war (the one provided describes only its initial stage), but I don't think that instructions regarding "strangers" on the deck could have changed significantly.
Saving a distressed submarine
For the US Navy, one of the worst submarine disasters was the sinking of the USS Thresher in the Atlantic on April 10, 1963, with 129 sailors on board.
In the aftermath of that deadly accident, the Navy created the SUBSAFE program, a quality assurance effort that aims to ensure that that a distressed submarine can surface after an accident.
Since the Navy's SUBSAFE program was created just two months after the USS Thresher disaster, the US Navy has only lost one submarine, the USS Scorpion in 1968 with 99 sailors aboard, but it had not actually been SUBSAFE certified.
The Navy also has two important submarine rescue capabilities. These include the Submarine Rescue Chamber Flyaway System for rescues down to 850 feet and the Submarine Rescue Diving Recompression System for rescues as deep as 2,000 feet.
These critical capabilities are overseen by Undersea Rescue Command at North Island Naval Air Station in Coronado, California, and can be flown out to almost anywhere in the world in 72 to 96 hours.
Most US Navy submarines have around 7 to 10 days of life support available, Submarine Forces said, but "it is still a race to ensure rescue systems get to the submarine before survivability time runs out."
Although they are available, these support assets were not mobilized during the recent training event, which was the latest iteration of the annual command-and-control tabletop exercise.
The US is also works with foreign partners, such as NATO's International Submarine Escape and Rescue Liaison Office. It was established in 2003 to support any country with submarines regardless of membership in the alliance.
"As submariners, we operate in an inherently high-risk environment, making it vital to act quickly and efficiently both as part of a submarine crew or ashore as the support element," Vice Adm. Daryl Caudle, the Submarine Force commander, said in a release.
"We train so that we are decisive, proficient, and ready in any scenario, because bringing our undersea warriors home after every underway is a no fail mission," Caudle added.
Navy accepts first atomic submarine
GROTON, Conn. (UP) -- The world's first atomic submarine, the Nautilus, will be turned over to the Navy today in a history making ceremony which will usher in new concepts of warfare at sea.
The Nautilus, which is believed to be capable of circling the globe without resurfacing, will be accepted by Adm. Jerauld Wright, commander of the Atlantic Fleet.
The Navy will enter a new epoch when the commissioning pennant, a narrow bunting with seven stars, is run up to the 55 million dollar submarine's short mast at the top of its conning tower.
The Nautilus is the first ship which will be driven by atomic energy. A few pounds of uranium in its revolutionary new power plant is expected to supply enough power for 30 days at sea without resurfacing.
The Nautilus will be commanded by Cmdr. Eugene P. Wilkinson, a 36-year-old former schoolteacher who was chosen not only for his exploits during World War II when he was a torpedo officer but for his knowledge of mathematics. Wilkinson graduated, not from Annapolis, but from San Diego State College.
How the U.S. Navy Might Have Built a Secret Submarine Base
There is something mythic and compelling about seashore scarps and naval bases — something drawing on archetypal imagery of treasure concealed in cave waters open to the sea.
Here's What You Need To Remember: In the 1970s the Los Alamos National Lab investigated an atomic rock-drilling concept called the Nuclear Subterrene, which like Rock-Site sounds like something out of Johnny Quest, but also really happened. One wonders what might have happened had the Navy put its nuclear expertise to work drilling holes in the ocean floor.
Point Sur is 600 feet of tough rock facing Pacific rollers that come 6,000 miles to pound the central California coast. Like the 19th-century lighthouse that marks the Point, the now-derelict compound of the former Naval Facility Point Sur evokes another era.
And it evokes a mystery — one involving secret underground naval bases, high-tech submarines and Cold War nuclear brinkmanship.
As late as the 1960s, Navy technicians and their families at Point Sur monitored undersea listening posts used to track Soviet subs. According to one legend, it wasn’t merely hydrophones the Navy ran from Point Sur, but submarines themselves based in giant man-made caverns dug into the rock.
There is something mythic and compelling about seashore scarps and naval bases — something drawing on archetypal imagery of treasure concealed in cave waters open to the sea. The ultimate supervillain’s lair, after all, is an island base with undersea access.
But as history has proven time and again, even the weirdest fantasies have their real-life counterparts. And those who dive for Atlantean gold sometimes surface with treasure. There really were — and are — some strange ideas deep down in the sea.
By 1966 the two surges into outer space and “inner space” were at their flood tide. While NASA gathered ever more momentum with monthly Gemini flights and a new Mission Control, the success of Sealab II and the CONSHELF III underwater habitat led to a presidential commission on oceanography and a bigger undersea commitment.
The Navy’s efforts to recover a lost hydrogen bomb off the coast of Spain that year and the loss of the attack sub USS Thresher three years before had brought new funding and discipline to deep submergence systems. In such heady times, dreams of colonizing the continental shelf within a generation seemed like sober predictions.
It was in this environment that C.F. Austin of the China Lake Naval Ordnance Test Station proposed the Rock-Site concept: manned undersea installations excavated into the rock of the seafloor. By applying well-understood principles employed for decades by the mining industry, Austin proposed that large bases could be constructed and operated anywhere suitable bedrock occurred in the ocean, at any depth.
Austin realized that even with mid-1960's technology, it would be possible to sink a wide shaft into the sea floor, seal and drain it, then use it as a staging area for further excavation. A tunnel-boring machine could be lowered into the shaft in pieces and then assembled to bore out more tunnels, including one for a small modular nuclear reactor much like those used at Camp Century in Greenland and McMurdo Base in Antarctica.
There’s very little hype in Austin’s report the bulk of it is taken up with documentation of tunneling methods and mining operations conducted under the sea floor. These often follow seams and drifts underground as they continue offshore.
According to Austin, one Nova Scotia mine, Dominion Coal’s Cape Breton operation, consisted of “a complex of many consolidated undersea mines ranging in depth from 200 to 2,700 feet below the sea floor, with a water cover of 60 to 100 feet. These mines span an area of approximately 75 square miles and presently employ some 4,100 men in the undersea workings.”
Among the benefits of Rock-Site, Austin noted its immunity to weather and currents, its shirt-sleeve environment and its (very) controlled access. And Austin was not thinking small. “Structures within the sea floor can easily be made large and comfortable enough to permit the quartering of crews and their families for extended periods of time,” he wrote, “and can be made large enough to serve as supply and repair depots for large submersibles.”
Recent research on hardened missile basing concepts have proven various techniques for creating submarine-sized structures in hard substrates. The Air Force’s development of underground silos, subways and central commands produced real-world hardware and experience with construction techniques.
In the 1970s the Los Alamos National Lab investigated an atomic rock-drilling concept called the Nuclear Subterrene, which like Rock-Site sounds like something out of Johnny Quest, but also really happened. One wonders what might have happened had the Navy put its nuclear expertise to work drilling holes in the ocean floor.
The Rock-Site concept also bore much in common with NASA’s designs for underground moon bases. Very likely all three concepts — invulnerable bastions, space outposts and ocean bases — would have shared solutions to issues ranging from environmental control to crew morale.
Austin foresaw that Rock-Site bases could be ideal for industrial uses such as fossil-fuel production and deep-sea mining. In the decades since Austin’s study, industry has created the tools need to realize his vision. Though it’s not atomic-powered, the world’s largest tunnel-boring machine is about to drill a two-mile-long tunnel beneath Seattle wide enough to hold an Ohio-class sub.
One enterprising firm servicing the offshore renewables industry has designed a remote drilling rig for planting monopile anchors on the seafloor, while others are developing entire subsea electrical grids. Consider a physically secure data center, with free cooling, in an industrial park beneath the sea …
A malfunctioning torpedo
USS Tang. US Navy
By the time Tang realized the torpedo was heading straight for it, there were only about 15 seconds until impact. O'Kane immediately ordered Tang to accelerate at full emergency power to get ahead of the torpedo, but it was too late.
The Mark 18's 570-pound warhead hit Tang's empty aft torpedo room and detonated. Half of the 87-man crew died instantly. With most of the rear compartments flooding quickly, Tang's stern section sank. The sub was longer than the water was deep, and the buoyancy of the unflooded forward compartments kept the bow above the surface.
Of the nine men on the bridge, three were able to successfully swim to the surface. One officer managed to swim out of the conning tower but was unable to close the hatch. Tang eventually sank and hit the sea floor 180 feet below.
About 30 men were trapped in the forward torpedo room. They burned sensitive documents and endured a Japanese depth charge attack before attempting to escape. This was the first time survivors escaped a sunken US submarine without assistance from the surface, and the first time a breathing device known as the Momsen lung was used. Of the 13 sailors that managed to escape, just eight made it to the surface, and only five would survive.
By Naval Institute Archives
April, 11th 1900
The US Navy accepts the design of it’s first official submarine the USS Holland, named after the engineer and designer John Philip Holland. Below are a couple of short articles from Proceedings professional notes section at the time of the Navy’s acceptance of the Holland.
From Proceedings 1898 #86
SUCCESSFUL TRIALS OF THE HOLLAND SUBMARINE BOAT.
The naval board appointed to inspect and report on the performance of the Holland submarine boat has reported that in the recent tests, held on November 6, in New York harbor, she fulfilled all the requirements laid down by the department.
These requirements were that she should have three torpedoes in place in the boat, she should have all arrangements for charging torpedoes without delay, and that she should be prepared to fire a torpedo at full speed both when submerged and at the surface. Lastly, the Holland was to make a run for two miles under water, starting from one buoy, running submerged for a mile to a second buoy, rising to discharge a torpedo at a mark near the second buoy, and then after diving again return submerged to the starting point.
In his report, Chief Engineer John Lowe, U. S. N. who was specially ordered to observe and report the preliminary trials, says: “I report my belief, after full examination, that the Holland is a successful and veritable submarine torpedo-boat, capable of making a veritable attack upon the enemy unseen and undetectable, and that, therefore, she is an engine of warfare of terrible potency which the government must necessarily adopt into its service.”
He further says that “this government should at once purchase the Holland and not let the secrets of the invention get out of the United States, and that the government ought to create a submarine torpedo boat station for the purpose of practice and drilling of crews, and that we need right off and right now fifty submarine torpedo vessels in Long Island Sound to protect New York, preserve the peace, and to give potency to our diplomacy.”
While we cannot agree with Mr. Lowe in his opinion that we need and presumably should build a whole fleet of torpedo-boats “right off and right now,” we do think that the Plunger, a larger boat of the Holland type now building for the government, should be immediately completed and further trials or the system carried out.-Scientific American.
Proceedings 1899 #92
HOLLAND SUBMARINE TORPEDO BOAT.
It is reported that this boat recently made a run of one and a half miles under water, remaining under the surface for twelve minutes. This is the longest run under water which the boat has yet made, and it is stated that she behaved herself very satisfactorily in every respect. A few of the leading particulars of this vessel will be of interest. She is 5 feet long, 10 feet 3 inches in diameter, and of 75 tons displacement. The steel hull is cigar-shaped, and the boat is propelled by a single propeller. The motive power equipment consists of a 50 horse-power gasoline engine and dynamo, the latter being directly coupled through a clutch at each end of its shaft to the propeller shaft and to the gas engine respectively.
A storage battery of 60 special type chloride accumulators is installed, the total weight of the battery being 45,000 pounds. The cells are constructed of steel, lined both inside and out with lead, and arc stated to be capable of discharging at 300 amperes for six hours or at 1000 amperes for half an hour. The arrangement of gearing permits of the propeller being run by the engine or of the cells being charged, except, of course, when the boat is submerged, when the motive power is supplied from the cells to the dynamo as a motor. Enough fuel is carried in the cellular bottom to propel the boat on the surface for 1000 miles at eight knots. The dynamo is 2 50 nominal horse-power machine, weighing 3500 pounds the armature speed is 800 revolutions per minute there are two commutators and a double-wound armature an overload to 150 horse-power is possible without detriment. The normal speed of the Holland is nine knots, at an expenditure of 50 horse-power. A 10 horse-power motor with a 7 horse-power Ingersoll air compressor is installed for supplying air at 2500 pounds pressure to the reservoirs. The compressed air is used to propel the torpedoes, emptying the water ballast tanks, steering and for supplying respiration.
A 1/2 horse-power motor is used to force the foul air into the water when the craft is submerged. and another of the same capacity to ventilate the battery when charging. The boat is caused to sink by an alteration of the pitch of horizontal diving rudders. When above the surface the craft is steered by observation through the port holes of the conning tower when below the surface, or nearly so, by compass or by a camera-Lucida arrangement fitted in a tube. The Holland’s armament consists of an 18-inch torpedo tube opening at the bow of the boat, and three whitehead automobile torpedoes are carried aboard. There is also an 8-inch aerial torpedo gun at the bow, and pointing aft a submarine gun, both of the latter capable of discharging 50-pound dynamite shells at high velocities. All the guns operate by compressed air, and can be discharged when the boat is submerged. The crew consists of five men.-The Engineer.
AA-1 class and V-boats Edit
The Gato-class boats were considered to be "Fleet Submarines". The original rationale behind their design was that they were intended to operate as adjuncts to the main battle fleet, based on standard-type battleships since World War I. They were to scout out ahead of the fleet and report on the enemy fleet's composition, speed, and course, then they were to attack and whittle down the enemy in preparation for the main fleet action, a titanic gun battle between battleships and cruisers. This was an operational concept born from experience in World War I. To operate effectively in this role, a submarine had to have high surface speed, long range and endurance, and heavy armament.  Limitations in submarine design and construction in the 1920s and 1930s made this combination of qualities very difficult to achieve.  The U.S. Navy experimented constantly with this concept in the post-World War I years, producing a series of submarines with less than stellar qualities and reliability, the AA-1 class (also known as the T class) and the V-boats, of which V-1 through V-3 were an unsuccessful attempt to produce a fleet submarine. 
Tambor and Gar class Edit
By 1931, the experimental phase of fleet submarine development was over and the Navy began to make solid progress towards what would eventually be the Gato class. By 1940, a much better developed industrial base and experience gained from the Porpoise-, Salmon-, and Sargo-class boats resulted in the Tambor and Gar classes. Finally, the U.S. Navy had hit the right combination of factors and now had the long-desired fleet submarine. 
Timing, however, conspired against the actual use of these boats in their assigned role. The attack on Pearl Harbor on 7 December 1941 destroyed the Pacific Fleet battle line and along with it the concept of the battleship-led gun battle, as well as 20 years of submarine strategic concept development. It left the fleet submarine without a mission. Fortunately, the same capabilities that would have enabled these submarines to operate with the fleet made them superbly qualified for their new mission of commerce raiding against the Japanese Empire.  
Gato class Edit
The Gato-class design was a near-duplicate of the preceding Tambor- and Gar-class boats. The only significant differences were an increase in diving depth from 250 feet (76 m) to 300 feet (91 m), and an extra five feet in length to allow the addition of a watertight bulkhead dividing the one large engine room in two, with two diesel generators in each room. The Gatos, along with nearly all of the U.S. Navy fleet-type submarines of World War II, were of partial double-hull construction. The inner pressure-resisting hull was wrapped by an outer, hydrodynamic hull. The voids between the two hulls provided space for fuel and ballast tanks. The outer hull merged with the pressure hull at both ends in the area of the torpedo room bulkheads, hence the "partial" double hull. Operational experience with earlier boats led the naval architects and engineers at the Navy's Bureau of Construction and Repair to believe that they had been unduly conservative in their estimates of hull strength. Without changing the construction or thickness of the pressure hull steel, they decided that the Gato-class boats would be fully capable of routinely operating at 300 feet, a 50-foot (15 m) increase in test depth over the preceding classes. 
The Gatos were slow divers when compared to some German and British designs, but that was mostly because the Gatos were significantly larger boats. Sufficient fuel bunkerage to provide the range necessary for 75-day patrols from Hawaii to Japan and back could be obtained only with a larger boat, which would take longer to submerge than a smaller one. Acknowledging this limitation, the bureau designers incorporated a negative (sometimes called a "down express") tank into the design, which was flooded to provide a large amount of negative buoyancy at the start of the dive. Based on later wartime experience, the tank was normally kept full or nearly full at the surface, then emptied to a certain mark after the boat was submerged to restore neutral buoyancy. At the start of the war, these boats could go from fully surfaced to periscope depth in about 45–50 seconds. The superstructure that sat atop the pressure hull provided the main walking deck when the boat was surfaced and was free-flooding and full of water when the boat was submerged. When the dive began, the boat would "hang" for a few extra seconds while this superstructure filled with water. In an attempt to speed this process, additional limber, or free-flooding, holes were drilled and cut into the superstructure to allow it to flood faster. By midwar, these measures combined with improved crew training got dive times down to 30–35 seconds, very fast for such a large boat and acceptable to the boat's crew. 
The large size of these boats did negatively affect both surfaced and underwater maneuverability when compared to smaller submarines. No practical fix for this was available due to the limitations of the installed hydraulic systems used to move the rudder. Although a point of concern, the turning radius was still acceptable. After the war, a few fleet boats were fitted with an additional rudder topside at the very stern. 
The class of boats had numerous crew comforts including air conditioning, refrigerated storage for food, generous freshwater distilling units, clothes washers, and bunks for nearly every crew member these were luxuries virtually unheard of in other navies. The bureau designers felt that if a crew of 60–80 men were to be expected to conduct 75-day patrols in the warm waters of the Pacific, these types of features were vital to the health and efficiency of the crew. They could be added without impact to the boat's war fighting abilities due to the extra room of the big fleet boat. The air conditioning in particular had a very practical application, too, besides comfort. Should a submarine submerge for any length of time, the heat generated by the recently shut-down engines, electronic gear, and 70 warm bodies will quickly raise internal temperatures above 100 °F (38 °C). High humidity generated by tropical waters will quickly condense and begin dripping into equipment, eventually causing electrical shorts and fires. Air conditioning, acting mostly as a dehumidifier, virtually eliminates this problem and greatly increases mechanical and electrical reliability. It proved to be a key factor in the success of these boats during World War II.  
Engine changes Edit
Twelve submarines of this class built by Electric Boat received what would be the final installations of the Hooven-Owens-Rentschler (HOR) double-acting diesel engine. The Navy had been tinkering with this engine off and on since 1937 because its unique design promised nearly twice the horsepower in a package the same size as other diesel engine types. Unfortunately, the HOR company ran into severe design and manufacturing problems, and these engines proved to be operational and maintenance nightmares.  Frequent breakdowns and utter unreliability had destroyed these engines' reputation with the Navy and they were all removed at the first opportunity and replaced by General Motors Cleveland 16-278A V-type diesels. The other Gato-class boats received either the Fairbanks-Morse 38D 8-1/8 nine-cylinder opposed-piston engine or the General Motors Cleveland 16-248 V-type as original installations. These engines were hardy, rugged, and well liked by the crews and served the boats quite well. 
Fairwater changes Edit
At the beginning of the war, Gato-class boats, as well as the Gar and Tambor classes, had fully shrouded fairwaters visually similar to modern nuclear submarines. Experience during the war led to the progressive reduction of this structure to reduce visibility and radar profile at the expense of underwater performance and foul-weather operating comfort. Most of the subs in postwar movies show the final result of these modifications. A side benefit of these modifications was the creation of convenient locations for antiaircraft guns. 
Seventy-seven of these boats were commissioned from November 1941 (Drum) through April 1944 (Croaker). Twenty of the 52 U.S. submarines lost in World War II were of this class, plus Halibut, a damaged boat that returned to the U.S., but was considered a constructive total loss and not repaired.  
Occasionally, some confusion arises as to the number of Gato-class submarines built, with some sources listing the total as 73, due to the transitional nature of the first four boats (SS-361 through SS-364) constructed under the second contract by the Manitowoc Shipbuilding Company of Manitowoc, Wisconsin. These were originally intended to be Balao-class subs and were assigned hull numbers that fall in the middle of the range of numbers for the Balao class (SS-285 to SS-416, SS-425, and S-426).  Manitowoc was a designated follow-on yard to Electric Boat they used construction blueprints and plans supplied by Electric Boat and used many of the same suppliers. The government-owned shipyards (Portsmouth Naval Shipyard and Mare Island Naval Shipyard) began to make the transition to the new Balao design in the summer of 1942. Electric Boat, due to the huge backlog of Gato-class construction, was not ready to make the transition to the new design until January 1943. Manitowoc had already completed their allotted production run of Gatos and could not switch over to the Balao design until Electric Boat supplied them with the plans. Faced with a work stoppage while they waited for Electric Boat to catch up, managers at Manitowoc got permission to complete four additional boats (SS-361 through SS-364) to Electric Boat's Gato-class plans. Manitowoc's first Balao-class boat was Hardhead.  
The Gato boats were authorized in appropriations for Fiscal Year 1941, as part of President Franklin Roosevelt's proclamation of "limited emergency" in September 1939.  The first boat laid down was actually USS Drum at Portsmouth Naval Shipyard on 11 September 1940. She was commissioned on 1 November 1941, and was the only Gato-class boat in commission when the war started. Gato herself was laid down on 5 October 1940 by the Electric Boat Company at Groton, Connecticut, and commissioned 31 December 1941.  Due to their large construction capacity, more than half (41) of the class was built at Electric Boat facilities three new slipways were added to the north yard and four slipways were added to the south yard to accommodate their production. In addition, the government purchased an old foundry downstream from the main yard, constructed 10 slipways, and turned the yard over to Electric Boat. Called the Victory Yard, it became an integral part of Electric Boat operations.  A total of 77 Gatos were built at four different locations (Electric Boat, Manitowoc, Portsmouth, and Mare Island).
All of the Gatos (with one exception, Dorado) would eventually fight in the Pacific Theater of Operations. However, in the summer of 1942, six new Gatos were assigned to Submarine Squadron 50 and sent to Rosneath, Scotland, to patrol the Bay of Biscay and to assist in the Operation Torch landings in North Africa. All in all, they conducted 27 war patrols, but could not claim any verified sinkings. Considered a waste of valuable resources, in mid-1943, all six boats were recalled and transferred to the Pacific. 
Once they began to arrive in theater in large numbers in mid-to-late 1942, the Gatos were in the thick of the fight against the Japanese. Many of these boats racked up impressive war records: Flasher, Rasher, and Barb were the top three boats based on tonnage sunk by U.S. submarines. Silversides, Flasher, and Wahoo were third, fourth, and seventh place on the list for the number of ships sunk.  Gato-class boats sank four Japanese submarines: I-29, I-168, I-351, and I-42 while only losing one in exchange, Corvina to I-176.
Their principal weapon was the steam-powered Mark 14 torpedo in the early war years, with the electric Mark 18 torpedo supplementing the Mark 14 in late 1943. Due to a stunted research-and-development phase in the Depression-era 1930s, and in great part due to the arrogance and stubbornness of its designer, the Naval Torpedo Station Newport under the Bureau of Ordnance, the "wonder weapon" Mark 14 proved to be full of bugs and very unreliable. They tended to run too deep, explode prematurely, run erratically, or fail to detonate. Bowing to pressure from the submariners in the Pacific, the bureau eventually acknowledged the problems in the Mark 14 and largely corrected them by late 1943. The Mark 18 electric torpedo was a hastily copied version of captured German G7e torpedo weapons and was rushed into service in the fall of 1943. Unfortunately, it also was full of faults, the most dangerous being a tendency to run in a circular pattern and come back at the sub that fired it. Once perfected, both types of torpedoes proved to be reliable and effective weapons, allowing the Gatos and other submarines to sink an enormous amount of Japanese shipping by the end of the war. 
The Gatos were subjected to numerous exterior configuration changes during their careers, with most of these changes centered on the conning tower fairwater. The large, bulky original configuration proved to be too easy to spot when the boat was surfaced it needed to be smaller. Secondly, the desire to incorporate new masts for surface- and air-search radars drove changes to the fairwater and periscope shears. Third, additional gun armament was needed, and cutting down the fairwater provided excellent mounting locations for machine guns and antiaircraft cannon.  The modifications (or mods) to the Gato-class conning tower fairwaters were fairly uniform in nature and they can be grouped together based on what was done when:
- Mod 1 – This is the original configuration with the covered navigation bridge, the high bulwark around the aft "cigarette" deck, and with the periscope shears plated over. All the early boats were built with this mod and it lasted until about mid-1942.
- Mod 2 – Same as mod 1, but with the bulwark around the cigarette deck cut down to reduce the silhouette. This also gave the .50 caliber machine gun mounted there a greatly improved arc of fire. Began to appear in about April 1942.
- Mod 3 – Same as mod 2, but with the covered navigation bridge on the forward part of the fairwater cut away and the plating around the periscope shears removed. In this configuration, the Gatos now had two excellent positions for the mounting of single 40 mm Bofors or twin 20 mm Oerlikon antiaircraft cannon, an improvement over the .50 caliber machine gun. This mod started to appear in late 1942 and early 1943.
- Mod 4 – Same as the mod 3, but with the height of the bridge itself lowered in a last attempt to lessen the silhouette. The lowering of the bridge exposed three I-beams on either side of the periscope shears. These exposed beams gave rise to the nickname "covered wagon boats". Began to appear in early 1944.
Variations on the above mods included the 1A (shortened navigation bridge), 2A (plating removed from periscope shears), and the 3A and 4A (which moved the SJ radar mast aft of the periscopes).  The conning tower fairwater of Flasher is preserved in Groton, Connecticut, in the mod 4A configuration, with two single 40 mm Bofors mounts.
Deck guns varied during the war. Many targets in the Pacific War were sampans or otherwise not worth a torpedo, so the deck gun was an important weapon. Most boats began the war with a 3-inch (76 mm)/50 caliber Mk. 17 gun (although some boats received older Mk. 6 mounts due to shortages). The 3-inch gun was the model originally specified for the Gato class, but war experience led to the removal of 4-inch (102 mm)/50 caliber Mk. 9 guns from old S-class submarines to equip front-line boats. Beginning in late 1943, almost all were refitted with a 5-inch (127 mm)/25 caliber Mk. 17 gun, and some boats had two of these weapons. Additional antiaircraft guns included single 40 mm Bofors and twin 20 mm Oerlikon mounts, usually one of each.
- sank the Japanese aircraft carrier Taihō. Taihō was the flagship of Vice-AdmiralJisaburo Ozawa's fleet during the Battle of the Philippine Sea and at the time Japan's newest carrier. , on her 12th patrol in July 1945, landed a small team from her crew on the shore of Patience Bay on Karafuto. They placed charges under a railroad track and blew up a passing train. Barb also conducted several rocket attacks against shore targets on this same patrol, the first ever by an American submarine. They used 5-inch unguided rockets fired from a special launching rack on the main deck.  sank the Japanese aircraft carrier Shōkaku. Shōkaku was one of six Japanese carriers that had participated in the attack on Pearl Harbor. sank a ship carrying Japanese tank reinforcements that were en route to Iwo Jima. went to the rescue of a grounded Dutch submarine HNLMS O-19, taking its crew on board and destroying the submarine when it could not be removed from the reef, the only international submarine-to-submarine rescue in history. was the only U.S. submarine sunk by a Japanese submarine (I-176) during the Second World War. along with Dace conducted an aggressive and successful attack against Japanese fleet units during the lead up to the U.S. invasion of Leyte Island in the Philippines in October 1944. The two boats sank the heavy cruisers Atago and Maya and severely damaged the heavy cruiser Takao. A few hours later, while maneuvering back to the scene to finish off the crippled Takao, Darter ran hard aground on Bombay Shoal off Palawan. Her entire crew was rescued and subsequent attempts to destroy the wreck were only partially successful.  As late as 1998, portions of Darter ' s hulk were still visible on the reef. recovered downed pilot LTJGGeorge H. W. Bush, future President of the United States, after his Grumman TBM Avengertorpedo bomber was damaged and eventually ditched during a bombing mission at Chichi-jima in the Pacific. was the top-scoring U.S. boat of the war, with 100,231 tons officially credited to her by the Joint Army–Navy Assessment Committee (JANAC). 's skipper, Howard W. Gilmore, earned the submarine force's first combat Medal of Honor for sacrificing his life to save his boat and his crew. Alone on the bridge after being wounded by enemy gunfire, and unable to reach the hatch after he had ordered the others below, he pressed his face to the phone and uttered the order that saved his boat and sealed his doom: "Take 'er down!"
- In Grunion, Mannert L. Abele earned the submarine force's first Navy Cross, when his boat engaged in a running battle with Japanese ships off Kiska in July 1942. Grunion was subsequently lost in this action. In 2006 and 2007, expeditions organized and led by Abele's sons, Bruce, Brad, and John, located and photographed the wreck of the Grunion using side-scan sonar and a remotely operated vehicle. was essentially the 53rd U.S. submarine loss of the war. Terribly damaged in an aircraft-borne depth charge attack on 14 November 1944, she barely limped back to port in Saipan. Temporarily patched up, she was sent back to the United States. Examined by engineers, she was found to be beyond economical repair and was decommissioned on 18 July 1945, never having made another war patrol. Her entire crew survived.  was commanded by Samuel D. Dealey, the only submarine commander of the war (perhaps the only one ever) to sink five enemy destroyers, four in a single patrol. , which sank two Japanese ships during her patrols, was lent to the Japanese Maritime Self Defense Force after the war, serving under the name Kuroshio. 's notable record during World War II included eight patrols in the Pacific. She sank the third- or second-most tonnage during the war. She served the U.S. Navy until 1967. is officially credited with sinking 23 ships, the third-most of any allied World War II submarine, behind only USS Tang and USS Tautog, according to JANAC figures. became famous in Edward L. "Ned" Beach's book Submarine! (which was a kind of eulogy to her). sank the Japanese submarine I-42 on the night of 23 March 1944, after the two subs dueled for position for over an hour. A week later, Tunny engaged the Japanese battleship Musashi and inflicted enough damage for Musashi to return to dry dock for repairs. , commanded by one of the submarine force's most famous skippers, Dudley W. "Mush" Morton, engaged in a running gun and torpedo battle with a convoy of four ships off the coast of New Guinea and destroyed the entire convoy. She was also one of the first U.S. subs into the Sea of Japan. She was sunk while exiting the Sea of Japan through the La Perouse Strait in October 1943 while on her seventh patrol. 
At the end of World War II, the U.S. Navy found itself in an awkward position. The 56 remaining Gato-class submarines, designed to fight an enemy that no longer existed, were largely obsolete, despite the fact they were only two to four years old. Such was the pace of technological development during the war that a submarine with only a 300-foot test depth was going to be of little use, despite being modern in most other aspects. Enough of the Balao and Tench boats, with their greater diving depth, remained that the Gatos were superfluous for front-line missions. The Greater Underwater Propulsion Power Program (GUPPY) modernization program of the late 1940s largely passed these boats by. Only Barb and Dace received GUPPY conversions these were austere GUPPY IB modernizations prior to their transfer to the Italian Navy.  However, the U.S. Navy found itself new missions to perform, and for some of these the Gatos were well suited.  The last two Gato-class boats active in the U.S. Navy were Rock and Bashaw, which were both decommissioned on 13 September 1969 and sold for scrap. 
Radar picket Edit
The advent of the kamikaze demonstrated the need for a long-range radar umbrella around the fleet. Surface ships refitted with powerful radar suites were put into service, but they proved vulnerable in this role, as they could be attacked, as well, leaving the fleet blind. A submarine, though, could dive and escape aerial attack. After experimenting with the concept on several Balao and Tench-class boats, and realizing that a deep diving depth was not overly important in this role, six Gatos were taken in hand (Pompon, Rasher, Raton, Ray, Redfin, and Rock) for conversion. They were lengthened by 24 feet (7.3 m) to provide additional space for an air control center and had powerful air-search and height-finding radars installed, with the after torpedo room converted into an electronics space with torpedoes and tubes removed. They also received a streamlined "sail" in place of the traditional conning tower fairwater. Redesignated SSR and called the "Migraine III" conversion, these boats were only moderately successful in this role, as the radars themselves proved troublesome and somewhat unreliable. The radars were removed and the boats temporarily reverted to general-purpose submarines after 1959.   
The threat of the Soviet Navy building hundreds of Type XXI-derived submarines (eventually the 215-strong Whiskey class and dozens of others) in the Atlantic led the U.S. Navy to adapt submarines to specifically hunt other submarines, a radically new role for the 1950s. Concluding that this role did not require a fast or deep-diving submarine (this line of thought would quickly change with the advent of nuclear power), seven Gatos were converted to SSKs (hunter-killer submarines) between 1951 and 1953, joining three purpose-built K-1-class SSKs entering service at that time. The Gato class was chosen because large numbers were available in the reserve fleet should rapid mobilization become necessary, and the deeper-diving classes were more suitable for GUPPY rather than SSK conversions. A streamlined GUPPY-style sail was installed, a large sonar array was wrapped around the bow (losing two torpedo tubes in the process), the boats were extensively silenced including the removal of the two forward diesel engines, and they received a snorkel. Grouper was the test boat for the concept, having her sonar array at the forward end of the sail instead of the better position at the bow. The other boats in the program included Angler, Bashaw, Bluegill, Bream, Cavalla, and Croaker. Eventually, more advanced sonars were installed on the new nuclear boats, with Thresher introducing the bow-mounted sonar sphere, and the SSK mission was folded into the regular attack submarine role. Tullibee (SSN-597) , commissioned in 1960, was an attempt to develop a slow but ultra-quiet nuclear-powered SSK equivalent, but no others were built. The slow and less capable diesel SSKs were decommissioned or reassigned to other roles in 1959, and all except Croaker and Cavalla (eventually preserved as memorials) were scrapped in 1968 and 1969.  
Guided missile submarine Edit
The Regulus nuclear cruise missile program of the 1950s provided the U.S. Navy with its first strategic missile capability. Tunny was converted in 1953 to house and fire this large surface-launched missile and was designated SSG (guided missile submarine). She could carry two of the missiles in a cylindrical hangar on the aft deck. She made strategic deterrent patrols with Regulus until 1964, when the program was discontinued in favor of Polaris. 
Transport submarine Edit
With the retirement of the Regulus missile system in 1965, Tunny was converted into a troop transport in 1966. She was redesignated as an APSS (transport submarine), replacing Perch in this role. Her Regulus hangar became a lockout chamber for UDT, SEAL, and Marine Force Recon teams in the Vietnam War. On 1 January 1969, Tunny ' s designation was changed to LPSS (amphibious transport submarine) however, she was replaced by Grayback and decommissioned in June of that year.   
Submarine oiler Edit
Guavina was converted to a SSO in 1950 to carry fuel oil, gasoline, and cargo to amphibious beachheads. She received additional "saddle" tanks wrapped around her outer hull to carry these fuels and a streamlined sail. After a few tests, the concept was dropped in 1951 as impractical, and Guavina served in the test role for a few years. In 1957, she converted back to the oiler/tanker role and carried the designation AOSS. This time, she experimented with refueling seaplanes at sea, which was potentially important, as refueling the nuclear-capable Martin P6M Seamaster at sea could improve the Navy's strategic strike capabilities. However, this mission, too, was dropped after a few years and Guavina was decommissioned.  
Sonar test submarine Edit
The development of advanced sonar systems took on a great deal of importance in the 1950s, and several fleet boats were outfitted with various strange-looking sonar transducer arrays and performed extensive tests. Two Gatos, Flying Fish and Grouper (previously the prototype hunter-killer boat) were assigned to these duties and proved to be key players in the development of new sonar capabilities. Grouper had all her forward torpedo tubes removed and the space was used as berthing for technicians and as a sonar lab. Flying Fish was decommissioned in 1954, but Grouper continued in the test role until 1968.  
Naval Reserve trainer Edit
Interested in maintaining a ready pool of trained reservists, the Navy assigned numerous fleet boats to various coastal and inland ports (even in Great Lakes ports such as Chicago, Cleveland, and Detroit) where they served as a training platform during the reservists' weekend drills. Twenty-eight Gato-class boats served in this capacity, some as late as 1971. In this role, the boats were rendered incapable of diving and had their propellers removed. They were used strictly as pierside trainers. These were in commission, but classed as "in commission in reserve", thus some were decommissioned and recommissioned on the same day to reflect the change in status.   
The U.S. Navy’s Virginia-Class: Stealth, Heavily Armed and Ready for War
The Virginia-class were the first American submarines to be designed using 3D computer modeling, a move that was supposed to save both money and time.
A number of submarine technology advancements since the end of the Cold War have arguably made the class into the deadliest sub hunters in existence.
The Virginia-class is the United States Navy’s newest nuclear-powered fast attack submarine, designed to hunt down and sink enemy submarines and other surface vessels. In the case of the Virginia-class, they are also fitted with vertical launching tubes that house Tomahawk missiles, affording the Virginia-class a land-attack capability in addition to being a primarily naval attack asset. The Virginia-class replaces the Los Angeles-class, the United States powerful but aging Cold War-era nuclear fast attack submarines.
One of the innovative technologies possessed by the Virginia-class is pump-jet propulsion, an improvement compared to traditional screw-type propellers. Though a variety of pump-jet designs exists, all of them essentially rely on a pump system to take in seawater and a nozzle to pump water out, creating forward movement. The advantages offered by pump-jet designs are numerous: they allow for higher top speeds than traditional propeller designs and are quieter—a crucial advantage in underwater games of cat-and-mouse.
The Virginia-class were the first American submarines to be designed using 3D computer modeling, a move that was supposed to save both money and time. Cost-saving measures were at a premium, as the class also supersedes the Seawolf-class an extremely well-armed and quiet though prohibitively costly fast-attack submarine class that was intended to replace the Los Angeles-class. Due to an extremely high $3 billion-plus per submarine, the Seawolves are represented by a paltry three hulls.
The Virginia-class comes in five blocks, or variants, that incorporate design improvements and cost-saving measures incrementally. The last block, block V, are radically different than the original block I Virginias and almost an entirely different class: they are about eighty feet longer in length than their predecessors, which allows them to house Virginia Payload Modules, increasing the amount of Tomahawk cruise missiles each submarine can carry—up to sixty-five missiles from approximately thirty-seven on previous Virginia blocks.
Most recently, the Virginia-class manufacturer, Electric Boat, announced they had been awarded $1.89 billion for an additional block V submarine, hull number SSN 811. The contract award allows Electric Boat to continue to produces Virginia-class at a rate of two hulls per year, a step seen by some as crucial for maintaining submarine numbers as the Los Angeles-class submarines are retired.
At this pace, the Virginia-class will likely be acquired until the mid-2040s, and are expected to remain in service for about thirty-three years. With that amount of longevity, the newest Virginia-class submarines would stay in service until the early 2070s.