The graveyard of the Atlantic: U-boats at the bottom of the ocean

This panorama of 33 individual images reveals how U-352, the first U-boat sunk by the U.S., has become an artificial reef, home to a plethora of marine life

These ghostly images, taken off the coast of North Carolina, show the first Nazi contribution to a region known by divers as 'the graveyard of the Atlantic'.
The panorama is made up of 33 individual images, all painstakingly aligned from 70ft underwater by dive photographers David Doubilet and Hal Silverman.
It reveals how U-352, the first U-boat sunk by the U.S., has become an artificial reef, home to a plethora of marine life.

The decay of U-352's aft section has exposed the stern torpedo tube. Type VIIC U-boats had five 21in torpedo tubes, four in the bow and one at the stern. It took four attempts to get the right conditions for the photo shoot

The remains of the conning tower jut out from the hull. Underwater photographers David Doubilet and Hal Silverman shot the images in the mosaic with a Nikon D3 camera and a Seacam underwater housing

The wreck is just one of several along the eastern seaboard of the U.S.. Many ships, including naval craft and cargo vessels, are deliberately sunk to create artificial reefs - as are more unusual objects such as trains and tanks
On April 7, 1942, commanded by Kapitanleutnant Hellmut Rathke, U-352, a Type VIIC U-boat, departed the French port of St Nazaire on its second Atlantic patrol. It took four weeks to cross the ocean, and was one of the first U-boats to attack shipping off the east coast of the U.S.
None of its raids were successful, however, and on May 9, desperate for a victory, Rathke fired on a Coast Guard vessel, the cutter USS Icarus. His torpedoes missed and having detected his position via sonar, the Icarus engaged with depth charges and then surface guns. U-352 sank about 25 miles off the North Carolina coast, where it remains today.
The 220ft vessel came to rest in one piece, listing heavily to starboard. Its position in coastal Gulf Stream waters, only 110ft deep, has made it a popular dive spot - though would-be explorers must share the wreck with thousands of bait fish, not to mention barracuda and tiger sharks.
The outer hull has decayed to reveal the skeletal remains of the pressurised inner hull, but many notable features remain, including the conning tower and torpedo tubes.

ALL PICTURE CREDITS: DAVID DOUBILET and HAL SILVERMAN / NATIONAL GEOGRAPHIC

Submersible Boiler to Silent Sea-Wolves

From the advent of the earliest of the type, submarine design has always pressed against the outer limits of the contemporary technological envelope. Inventors and engineers have, of necessity, incorporated new and untested machinery and equipment into their craft in order to meet their goals of creating effective undersea vessels. The underwater environment, moreover, is unforgiving; errors in operation or failures of equipment have very dangerous and even fatal consequences. Success in submarine design, therefore, has come to those naval architects who have combined innovation and experimentation with substantial direct, prior experience or knowledge.

The obvious potential military advantages of the stealthy and lethal capabilities of successful submarines soon attracted the attention of admiralties around the world. Early designers of practical craft found a relatively ready market for their wares, either through export or license construction by their customers. Designs by the German Wilhelm Bauer were constructed in Germany and Russia, while George Garrett’s boats, built by the Swedish industrialist Thorsten Nordenfeldt in Sweden and Britain, were marketed to Greece, Turkey, and Russia. Beginning in the years around 1900, boats by Maxime Laubeuf in France, the Italian Cesare Laurenti, and above all, John P. Holland in the United States, found ready markets in navies around the world in the years before World War I.

The maturation of submarines as a result of operations during World War I expanded the global demand for the type. Design teams with successful records dominated this worldwide arms market. Firms from Britain, France, Germany, Italy, and the United States prevailed in this trade in submarines. In the German case, since indigenous submarine design and construction had been prohibited by the Versailles Treaty, the design teams established themselves across the border in the Netherlands and contracted out construction to yards in other European countries. A similar situation pertained after World War II, although Italian designs, no longer on the cutting edge, faded from the export market, while the emphasis on nuclear propulsion in the United States led that nation to withdraw from overseas sales to avoid the distribution of sensitive technologies. Its place was taken by substantial export of both vessels and designs by the Soviet Union, the resurgence of the German submarine industry, and the maturing of Swedish design and construction.

GLOSSARY

Admiralty: Shorthand terminology for the Royal Navy’s Board of Admiralty, which heads its central administration. Unlike most such boards, it includes both the civilian political appointees and the professional heads of the fleet.

Air Lock: A watertight compartment through which a diver may pass between a submarine and the sea, pausing within it while the air pressure is equalized with the external environment.

Ballast Tank: A tank that may be filled or emptied of water to increase or decrease a boat’s displacement.

Ballast Tank, Saddle: Ballast tank mounted outside the main structure of the hull, named by analogy with saddlebags.

Bridge: The ship’s navigating and control station.

Bulge: Structures built onto a ship’s side beyond the primary hull structure. Initially these were used to enhance protection against damage from a torpedo hit but they came to be employed more to enhance stability by increasing a hull’s internal volume.

Casing: A light non-pressure-resistant structure designed to improve submarine performance and/or enhance personnel access on the surface.

Catapult: A device for launching aircraft into the air.

Conseil Superieur: The French Navy’s professional leadership.

Conning Tower: Navigation station outside the main hull.

Convoy: A group of merchant vessels traveling together under escort.

Depth Charge: An explosive charge detonated at a preset depth.

Diving Planes: Horizontal control surfaces used to move a submarine in a vertical plane.

Drop-Collar: A mechanical arrangement suspending a torpedo that may be release remotely.

Dynamite Gun: A gun using compressed air as propellant for its missile, which had a dynamite explosive charge.

General Board: The professional leadership of the United States Navy until 1948.

Horsepower

Brake Horsepower (bhp): The measure of the power output of internal combustion engines.

Indicated horsepower (ihp): The measure of the power output of reciprocating steam
engines.

Shaft Horsepower (shp): The measure of the power output of turbine engines.

Machinery Types

Diesel: Internal combustion engines using oil fuel and compression ignition.

Triple Expansion: Reciprocating steam engines using multiple cylinders to maximize steam usage.

Turbine: Engines that use the passage of steam or hot gases to rotate encased fan blade assemblies to generate power.

Magazine: Stowage space for munitions.

Mine: An underwater explosive charge.

Monitor: A small shallow draft vessel carrying heavy guns, primarily intended for shore bombardment.

Pressure Hull: The main body of a submarine that is reinforced to withstand water pressure.

Radar: Electronic location equipment, initially for search only but rapidly developed to provide gunnery control and missile guidance.

Radome: A protective enclosure for a radar antenna.

Sail: Streamlined superstructure containing conning stations.

Sheer: The shape of the top of a ship’s hull as viewed from the side.

Sonar: Acoustic detection equipment for locating submarines.

Spar Torpedo: A warhead attached to a pole or spar, allowing it to project ahead of the attacking vessel.

Submarine: A vessel that normally operates submerged. Usually also used to describe any vessel that may operate underwater, even for a limited period.

Submersible: A vessel that normally operates on the surface but may be submerged controllably at will.

Superstructure: All a ship’s structure above the hull’s sheer.

Topweight: The component of the ship’s weight that is above its center of gravity.

Torpedo: Self propelled underwater weapon.

Torpedo, Acoustic: A torpedo that that is self-guided toward the sound of a target’s propellers.

Torpedo, Homing: A torpedo that is self-guided to its target by emissions (usually sonic).

Torpedo, Wire-guided: A torpedo guided to its target by an operator on the launching vessel using signals transmitted through a trailing wire.

Torpedo Pistol, Contact: Torpedo detonator that uses contact with its target for initiation.

Torpedo Pistol, Magnetic: Torpedo detonator that used its target’s magnetic field for initiation.

Torpedo Tube: Tube for launching torpedoes, usually by the pressure of introduced compressed air, a ram, or by allowing the torpedo to exit under its own power (swim-out tube).

Trim Tank: Small tank used for fine adjust of a submarine’s depth and inclination.

Variable Pitch Propeller: A propeller whose blades may be twisted to vary their angle according to power needs.

Warship Types

Battlecruiser: A battleship type that trades armor protection for higher speed.

Corvette: A small low-speed escort vessel.

Cruiser, Armored: A cruising warship type used until the first quarter of the 20th century that depended on an armored belt for its main protection.

Cruiser, Heavy: A cruiser armed with 8-inch guns.

Cruiser, Light: A cruiser armed with 6-inch or smaller guns.

Cruiser, Protected: A cruising warship type used until the first quarter of the 20th century that depended on an armored deck for its main protection.

Destroyer: A relatively small, fast, multi-role warship, originally designed to defend against torpedo boats but later also used for surface torpedo attack and antiaircraft and antisubmarine defense.

Dreadnought: A battleship armed primarily with eight or more very large caliber guns.

Escort Carrier: A small aircraft carrier primarily operating antisubmarine aircraft.

Frigate: A more sophisticated development of a corvette.

Pre-Dreadnought: A battleship usually armed with four large caliber guns and a substantial secondary armament.

Q-ship: A commissioned warship disguised as a merchant vessel carrying concealed weapons used to attack submarines induced to surface.

Sloop: A sophisticated antisubmarine and antiaircraft escort vessel.

Torpedo Boat: A small fast vessel, originally for attack with torpedoes but later often used as a fast antisubmarine vessel.

Victor III SSN, (Type 671RTM)

Approximately four Victor III class boats are currently operational with the Russian Navy, the only survivors of a total of 48 boats built from 1968 until 1993 in three distinct variants. By Russian standards they are relatively small but they are nevertheless well armed and equipped. The original Type 671 Victor I displaced 4,300 tons on the surface and could dive to 1,300 ft (400m); 15 were completed between 1968 and 1975. A further seven Type 671 PT Victor IIs entered service between 1972 and 1978 and these had a hull lengthened by 16ft (5m) and displacement rose to 4,500 tons. The current Type 671 PTM Victor II had a further section added to the hull, increasing the length to 345ft (105m) and displacement to 4,900 tons, and could be distinguished visually by a large streamlined pod mounted above the stern which contained the towed array sonar system. One boat was modified to incorporate a trials launch system in front of the sail for the SS-N21 missiles, which are normally fired from the forward torpedo tubes, and this boat is sometimes referred to as a Victor IV (Type 671 RTMK).

The last Victor IIIs built utilised eight-bladed propellers and are much quieter than their predecessors, and are almost comparable to the US SSNs in this respect. A total of 26 Victor IIIs were built, commissioning between 1978 and 1991, but today no more than four are active and all Victor I and IIs have been laid up or scrapped. In the long term the remaining Victors will be replaced by the newer Akula and Sierra classes, although construction of the latter appears to have ceased some time ago.

SPECIFICATION Type: SSN Class: Victor (Type 671 RTM) Displacement: 4,850 tons surface, 6,300 tons dived length: 351.1ft 11.07m) Beam: 34.8ft 11.06m) Draught: 24.3ft (7.4m) Machinery: nuclear; 2 VM-4 PWR reactors, 150MW; 2 turbines, 31 ,000hp; 1 shaft; 2 spinners Speed & Range: 30kt dived Complement: 98 Missiles: SS-N-21 Sampson long-range SLCM ASW & USW: 2 26in (660mm) and 4 21 in (553mm) torpedo tubes, various torpedoes; SS-N-15 Starfish A/S missile launched from 21 in 1533mm) torpedo tubes; SS-N-16 Stallion long-range A/S missile launched from 26in 1660mm) tubes; or 36 mines in lieu of torpedoes Sensors: radar: Snoop Tray surface search; sonar: Shark Gill hull-mounted search and attack; Shark Rib passive flank array; Mouse Roar hull-mounted high-frequency active attack; Scat 3 passive towed array.

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Walrus SSK,

Bruinvis (S810), one of four Walrus class SSKs.

Walrus (S802). Note the cruciform stern planes.

The initial contract for the first two boats was awarded in 1979 with a second pair ordered in 1985. Construction was delayed by design changes including a lengthening of the hull to accommodate larger diesel generators and also by a serious fire aboard Walrus while it was being fitted out. Consequently the first to commission was Zeeleeuw in 1990, followed by the repaired Walrus in 1992. The second pair, Dolfljn and Bruin vis, were laid down in 1986 and 1988, and completed in 1993 and 1994 respectively.

The basic design of these boats was based on the Zwaardvis class, which has now been retired. The hull dimensions were similar but normal diving depth was increased from 650ft (200m) to 1,000ft (300m) by the use of stronger HT steel. A total of 20 Harpoon missiles or torpedoes can be stowed. The latter may include Mk.48 Mod.4 heavyweight wire-guided torpedoes with a range of 23.5 miles (38km) at 55kt or 31 miles (50km) at 40kt, or Honeywell NT37D wire-guided ASW torpedoes with a range of 12.5 miles (20km). As an alternative, up to 40 mines may be carried instead of the torpedoes and missiles. Designed for ocean operations, the Walrus class boats have an endurance of 60 days at sea.

SPECIFICATION Type: SSK Class: Walrus Displacement: 2,465 tons surface, 2,800 tons dived Length: 223ft (167.7m) Beam: 27.6ft (18.4m) Draught: 23ft (7m) Machinery: diesel electric; 3 SEMT-Pielstick 12 PM 200VG diesels, 6,300hp; 3 alternators, 288MW; 1 Holec motor, 6,910hp; 1shaft Speed & Range: 20kt dived; 10,000 miles (16,100km) (13kt at surface) Complement: 52 Missiles: Boeing Sub Harpoon long-range SSM (launched from torpedo tubes) ASW & USW: 4 21 in (533mm) torpedo tubes, Mk48 long-range wire-guided and NT370 wire-guided medium-range torpedoes Sensors: radar: ZW07 surface search; sonar: TSM 2272 hull-mounted active/passive search and attack; Type 2026 passive towed array; OUUX 5 passive ranging and intercept.

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R-class

British submarine design took a decisive turn away from Holland’s concepts with the development of the D class, which entered service in 1908. These much larger boats introduced saddle tanks for ballast and marked the British shift to long-range craft optimized for surface operation and seaworthiness. They set the pattern for subsequent British development that was broken only by the R class, built as antisubmarine platforms and optimized for underwater performance, which entered service very late in World War I.
R-1 (24 April 1918), R-2 (25 April 1918), R-3 (8 June 1918), R-4 (8 June 1918)
Builder: Chatham
R-7 (14 May 1918), R-8 (28 June 1918)
Builder: Barrow
R- 9 (12 August 1918), R- 10 (5 October 1918)
Builder: Armstrong
R-11 (16 March 1918), R-12 (9 April 1918)
Builder: Cammell Laird
Displacement: 410 tons (surfaced), 503tons (submerged)
Dimensions: 153990 x 15930 x 11960
Machinery: 1 diesel engine, 1 electric motor, 1 shaft. 240 bhp/1200 shp = 9.5/15knots
Range : 2000 nm at 8 knots surfaced; submerged characteristics unknown
Armament: 6 x 180 torpedo tubes (bow), total 12 torpedoes
Complement: 22
Notes: The Admiralty designed this class as fast boats that could overtake and sink enemy submarines. The hull cross-section duplicated that of the H class: the hull form was similar, and the whole external form was streamlined for superior underwater performance. Machinery was half an H-class installation. The bow compartment contained five powerful, sensitive hydrophones with suitable direction-finding equipment to locate and target submarines underwater. These boats met all expectations, but the end of World War I seemed to terminate their mission; they were discarded in February 1923.

M-class

The British Royal Navy M-class submarines were a small class of diesel electric submarine built during World War I. The unique feature of the class was a 12-inch (305 mm) gun mounted in a turret forward of the conning tower.
Background
They were ordered in place of the last four of the first group of steam propelled K-class submarines, K17-K21, the original orders being cancelled.

They were initially intended as coastal bombardment vessels, submarine monitors, but their role had been changed before detailed design begun. The intention was that merchant ships could be engaged at periscope depth or on the surface using the gun, rather than torpedoes. At that time torpedoes were considered ineffective against moving warships at more than 1000 yards (900 m). Nevertheless it is unlikely that a well-constructed ship would be sunk by a single 12-inch (305 mm) shell hit.
Design
The guns were 12-inch (305 mm) 40 calibre Mark IX guns from spares for the Formidable-class battleships. The mounting allowed them to elevate by 20 degrees, depress 5 degrees and train 15 degrees in either direction from the centre line. The weapon was normally fired from periscope depth using a simple bead sight on the end of the gun aligned with the target through the periscope at a range of around 1200 metres. The exposure time of the gun above the surface was around 75 seconds. The submarine had to surface to reload the gun, which would take about 3 minutes. In practice the concept was not very successful and only three of the four M-class boats ordered were completed, all between 1917 and 1918. M-class submarines are sometimes called submarine monitors.

M1 and M2 also had four 18-inch (450-mm) torpedo tubes whilst M3 and M4 had 21-inch (533 mm) diameter tubes and were 3 metres longer to accommodate them.
Service
    * M1 was the only one to enter service before the end of World War I but did not see action. She was captained during her sea trials by experienced submariner Commander Max Horton after his return from the Baltic, and was later lost with all hands while on exercise in the English Channel near Start Point in Devon after a collision with a Swedish collier, SS Vidar, on 12 November 1925. The wreck of M1 was discovered by a diving team led by Innes McCartney in 1999 at a depth of 73 metres. Later that year the wreck was visited again by Richard Larn and a BBC TV documentary crew, and the resulting film was aired in March 2000.
    * M2 was converted to a seaplane carrier in 1925, a hangar replacing the gun turret. She was lost off Chesil Beach on 26 January 1933. It is thought that the hangar door was opened prematurely. M2 lies in much shallower water, 32 metres deep with the top of the conning tower only 20 metres below the surface at low tide. She is a popular attraction for local scuba divers with as many as six boats anchored above her on busy days.
    * M3 was converted to a minelayer in 1927 with stowage for 100 mines, primarily to test the mine-handling equipment of the Porpoise class. The mines were carried on a conveyor belt which ran along her upper deck and covered over by an enlarged casing. The mines were laid through a door at the stern. She was scrapped in 1932 after the trials had been completed.
    * M4 was broken up before completion.

In 1924 all three completed members of the class were used to test hull camouflage to reduce the visibility of submarines from aircraft—M1 was painted grey-green, M2 dark grey and M3 was painted dark blue.
References
    * Martin H. Brice M-class Submarines, Outline Publications, 1983, ISBN 0-946784-00-0
    * D.K. Brown, The Grand Fleet, Warship Design and Development 1906-1922, Caxton Editions, 2003, ISBN 1-84067-531-4

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