The Fleet Type Submarine

DEVELOPMENT OF THE SUBMARINE

A. EARLY UNDERWATER DEVICES

1A1. Early Greek devices. The submarine first became a major factor in naval warfare during World War I, when Germany demonstrated its full potentialities. However, its advent at that time, marked by wholesale sinkings of Allied shipping, was in reality the culmination of a long process of development.

Ancient history includes occasional records of attempts at underwater operations in warfare. The Athenians are said to have used divers to clear the entrance of the harbor of Syracuse during the siege of that city; during his operations against Tyre, Alexander the Great ordered divers to impede or destroy any submarine defenses the city might undertake to build. But in none of these records is there a direct reference to the use of submersible apparatus of any kind. There is, however, a legend that Alexander the Great himself made a descent into the sea in a device which kept its occupants dry and admitted light.

In the Middle Ages, the Arabian historian Boha-Eddin reports that a diver using submersible apparatus succeeded in gaining entrance into Ptolemais (Acre) during the siege of that city in A.D. 1150. And in 1538, a diving bell was built and tested at Toledo, Spain. Although it attracted the attention of the Emperor Charles V, the device was never further developed and passed quickly into oblivion.

1A2. Bourne's idea. Not until 1580 does any record appear of a craft designed to be navigated under water. In that year, William Bourne, a British naval officer, made designs of a completely enclosed boat which could be submerged and rowed under the surface. The device consisted of a wooden framework covered with waterproofed leather. It was to be submerged by reducing its volume as a result of contracting the sides through the use of hand vises. Although Bourne never built this boat, a similar construction

sponsored by one Magnus Pegelius was launched in 1605. But the designers made one serious oversight. They failed to consider the tenacity of underwater mud, and the craft was buried at the bottom of a river during initial underwater trials.

1A3. Van Drebel's submersible. It is to Cornelius Van Drebel, a Dutch physician, that credit is usually given for building the first submarine. To him is conceded the honor of successfully maneuvering his craft, during repeated trials in the Thames River, at depths of 12 and 15 feet beneath the surface.

Van Drebel's craft resembled those of Bourne and Pegelius in that its outer hull consisted of greased leather over a wooden framework. Oars, extending through the sides and sealed with tight-fitting leather flaps, provided propulsion either on the surface or when submerged. Van Drebel built his first boat in 1620 and followed it later with two others both larger but embodying the same principles. It is reported that after repeated tests, James I took a trip in one of the larger models and demonstrated its safety. But despite this evidence of royal favor, the craft failed to arouse the interest of the navy in an age when all conception of the possibilities of submarine warfare was still far in the future.

1A4. Eighteenth century plans. Submarine boats seem to have been numerous in the early years of the 18th century. By 1727 no fewer than 14 types had been patented in England alone.

An unidentified inventor whose work is described in the Gentleman's Magazine for 1747 introduced an ingenious device for submerging and surfacing his submarine. His craft was to have had a number of goatskins built into the hull, each of which was to be connected to an aperture in the bottom. He planned to submerge the vessel by filling the skins with water, and to bring it to the

surface again by forcing the water out of the skins with a "twisting rod." This seems to have been the first approach to the modern ballast tank. By that time, ideas were plentiful, some of them fanciful and grotesque, but some containing elements capable of practical

application. Lack of full understanding of the physical and mechanical principles involved, coupled with the well-nigh universal conviction that underwater navigation was impossible and of no practical value, postponed for more than another hundred years the attempt to utilize a submarine in warfare.

B. EARLY SUBMARINES

1B1. David Bushnell's Turtle. During the American Revolutionary War, a submarine was first used as an offensive weapon in naval warfare. The Turtle, a one-man submersible invented by David Bushnell and hand-operated by a screw propeller, attempted to sink a British man-of-war in New York Harbor. The plan was to attach a charge of gunpowder to the ship's bottom

with screws and explode it with a time fuse. After repeated failures to force the screws through the copper sheathing on the hull of the HMS Eagle, the submarine gave up, released the charge, and withdrew. The powder exploded without result, except that the Eagle at once decided to shift to a berth farther out to sea.

Figure 1-1. The TURTLE of David Bushnell, from a drawing by Lt. F. M. Barber, USN, 1875.

1B2. Fulton's Nautilus. Although his name is most often associated with the invention of the steamboat, Robert Fulton experimented with submarines at least a decade before he sailed the Clermont up the Hudson. His Nautilus was built of steel in the shape of an elongated oval, and was somewhat similar in structure to today's submarine. A sail was employed for surface propulsion and a hand-driven propeller drove the boat

development of the craft, even though his model displayed some of the best features of any submarine up to that time.

1B3, The Confederate "Davids". Development of the submarine boat was held back during all of this period by lack of any adequate means of propulsion. Nevertheless, inventors continued resolutely with

Figure 1-2. Fulton's NAUTILUS, about 1800

when submerged. A modified form of conning tower was equipped with a porthole for observation, since the periscope had not yet been invented. In 1801, Fulton tried to interest France, Britain, and America in his idea, but no nation ventured to sponsor the

experiments upon small, hand-propelled submersibles carrying a crew of not more than six or eight men. On 17 February 1864, a Confederate vessel of this type sank a Federal corvette that was blocking Charleston harbor. This first recorded instance of a

Figure 1-3. The HUNTLEY, one of numerous "Davids" constructed during the War Between the States.

submarine sinking a warship was accomplished by a torpedo suspended ahead of the bow of the Huntley as she rammed the Housatonic.

1B4. Garrett's steam propulsion. Interest in the improvement of the submarine was active during the period of the War Between the States, but the problem of a suitable means of propulsion continued to limit progress. Steam was tried and finally in 1880 an English clergyman, the Rev. Mr. Garrett, successfully operated a submarine with steam from a coal-fired boiler which featured a retractable smokestack. During the same period, a Swedish gun designer, Nordenfelt, also constructed a submarine using steam and driven by twin screws. His craft, which

could submerge to a depth of 50 feet, was fitted with one of the first practical torpedo tubes.

1B5. Electric propulsion. Meanwhile, electric propulsion machinery had proved its utility in many fields, and in 1886, an all-electric submarine was built by two Englishmen, Campbell and Ash. Their boat was propelled at a surface speed of 6 knots by two 50-horsepower electric motors operated from a 100-cell storage battery. However, this craft suffered one major handicap; its batteries had to be recharged and overhauled at such short intervals that its effective range never exceeded 80 miles.

C. MODERN SUBMARINES

1C1. Holland's Plunger, Antedating the efforts of Nordenfelt were the experiments of J. P. Holland of New Jersey, who launched his first boat in 1875. Although his early

models embodied features that were discontinued as development progressed, many of his initial ideas, perfected in practice, are in use today. Outstanding in importance was

the principle of submergence by water ballast, and the use of horizontal rudders to dive the boat. However, not until 1895, did Holland, in competition with Nordenfelt, finally receive an order for a submarine from the United States Government. The vessel was propelled by steam on the surface and by electricity when submerged. This craft was named the Plunger. The original craft was redesigned frequently during construction and finally abandoned altogether in favor of a newer model already building in the Holland shipyard. This was Holland's ninth submersible, but it was the first to be delivered to the United States Government. It was delivered in 1900, and was the basic design of all British submarines to follow.

1C2. Lake's Submarines. Simon Lake, who began building submarines in 1894, designed them primarily with peacetime uses in mind.

His vessels could travel about on the sea bottom, and had an air lock which permitted a passenger in a diving helmet to emerge from the hull to walk about and explore. In fact, Lake used his vessels extensively in commercial salvaging operations. His first model, the Argonaut, Jr. was solely an experimental one. It was built of two layers of yellow pine with a sheet of canvas between them, and was operated by hand.

It was followed in 1897 by the Argonaut, a cigar-shaped hull 36 feet long and powered by a 30-horsepower gasoline engine. This craft could submerge to the bottom of a lake or river and roll along at bottom on three wheels; or, for navigating. The wheels could be raised and carried in pockets in the keel. In 1898 the Argonaut traveled under its own power through heavy November storms from Norfolk to New York, and was thus the first

Figure 1-4. The ARGONAUT JR.

submarine to navigate extensively in the open sea. In 1906 Lake built the Protector and sold it to Russia. After it had successfully passed various severe tests there, Lake built a number of submersibles on contract for the Russian Government.

1C3. Conclusion. Thus the fundamental principles of construction and operation of submarine boats had been determined and demonstrated before the outbreak of World War I. By that time, too, internal combustion engines, both gasoline and Diesel, were available for use as practical power plants.

The invention of the periscope had materially increased the practical feasibility of underwater navigation. And the primary weapon of the submarine, the torpedo, had been perfected for use. Thus, the preliminary development of the submarine was finished, and the vessel was ready to take its place as a major factor in naval strategy. In place of the tiny, one-man contraptions that first dared to venture beneath the surface had come effective weapons, only a little short of the powerful, 70-man, fleet-type submarines that range the seas today.

D. GENERAL DATA

1D1. Type of Construction. When the submarine rests on the surface, so little of it is seen above the water that it has the appearance of being longer and more slender than

it really is. Actually, the modern fleet type submarine is approximately 312 foot long with a superstructure deck tapering almost to a point, both fore and aft, from its greatest width of approximately 16 feet amidship.

Figure 1-5. USS O-7 (1918)

Figure 1-6. USS R-6 (1919).

Figure 1-7. USS S-17 (1921)

Figure 1-8. USS S-46 (1925).

Figure 1-9. USS NARWHAL (1930).

Figure 1-10. USS BLACKFIN (1944).

Beneath the superstructure deck is the all-welded hull; actually it is two hulls, for the fleet-type submarine is a double-hull vessel. To understand the construction of a submarine, one must first appreciate the conditions under which the vessel operates below the surface. This means that the submarine must at all times be watertight, otherwise self-destruction would result. The construction of the submarine, therefore, is on the basis of the fabrication of a series of watertight containers into one large watertight cylinder by means of watertight joints. However, since the submarine must operate at times at great depths, these watertight containers must be strong enough to withstand the pressure head of sea water at that depth. Therefore, the watertight containers must be pressure vessels, that is, watertight containers or cylinders capable of withstanding great

pressure. The fabrication of these containers into the hull of the vessel is illustrated in Figure 1-11.

Pressure vessels, while capable of withstanding great pressure, do not in themselves possess great rigidity. Being subject to mechanical action (leverage), they must be secured to each other by one common strength member (the keel), as well as by watertight connections (bulkheads). The submarine with its keel, pressure hull, and watertight bulkheads is shown in Figure 1-12.

In the double-hull type of submarine, the pressure hull is inside the outer hull; between the two hulls are the water and the fuel oil tanks. The double-hull construction extends from the after bulkhead of the forward torpedo room to the forward bulkhead of the after torpedo room. The pressure hull,

Figure 1-11. Type of construction, showing arrangement of compartments, without the superstructure or tanks.

or inner hull, extends from the forward bulkhead of the forward trim tank to the after bulkhead of the after trim tank. Above the hull is built a non-watertight superstructure which forms the main deck, for use when surfaced.

A gun, usually a 5"/25, wet type, is mounted topside. The space below the deck is used as locker space for stowing anchor gear, lines, and other gear that cannot be damaged by water. Ready ammunition in boxes and the ship's boat are also kept here.

The deck is perforated on either side with circular holes among the entire length to prevent air pockets from forming within the superstructure when it becomes flooded. A watertight tower, know as the conning tower, extends upward through the superstructure amidships. The top of the conning tower is used as a bridge when on the surface, but when submerged, the control of the boat is maintained either from the conning tower or from a compartment directly below it, known as the control room. Periscopes

Figure 1-12. Type of construction, showing the general arrangement of the superstructure.

operated from the conning tower extend above the bridge and are used for making observations when submerged.

1D2. Size. In the accompanying table are shown dimensional data of the fleet type submarine.

1D3. Depth and pressure. The modern fleet

Individual compartments are air tested for tightness only to a pressure of 15 psi. Watertight bulkheads are designed structurally and strengthened through reinforcements to withstand the pressure at the previously mentioned test depths.

The total pressure that the hull must

Displacement (designed)	1,523 tons
Displacement (surface)	1,816 tons (diving trim
Length (over-all)	311'-9"
Breadth (extreme)	27"-4"
Mean draft (surface)	15'-3" (diving trim)
Number of frames	139
Frame spacing (except 35 to 62 and 69 to 105 spacing 30")	24" center to center
Freeboard at stern	3'-11"
Freeboard at bow	12'-5"
Diameter pressure hull (max.)	16'-0 3/8"
Distance from keel to centerline of hull	12'-0"
Floodable space
Forward torpedo room	4,481 cu. ft.
Forward battery compartment	4,056 cu. ft.
Control room	4,653 cu. ft.
Conning tower	760 cu. ft.
After battery compartment	5,821 cu. ft.
Forward engine room	4,535 cu. ft.
After engine room	4,277 cu. ft.
Maneuvering room	3,410 cu. ft.
After torpedo room	3,455 cu. ft.

Total floodable space	35,448 cu. ft.

type submarine is built to withstand the pressure of a head of sea water, consistent with requirements as shown by battle experience and with the Bureau of Ships specifications. The pressure is measured in actual submergence tests from the surface of the water to the axis of the vessel through its pressure hull.

withstand is actually the differential pressure between the interior hull pressure and the external head of water at a given depth.

1D4. Main propulsion, speed and cruising radius. The average fleet type submarine is driven by four main propulsion diesel engines, each capable of producing 1600 hp.

Figure 1-13. Torpedo tubes.

Figure 1-14. Deck gun, 5"/25.

Figure 1-15. Anti-aircraft gun, 40 mm.

Figure 1-16. Anti-aircraft gun, 20 mm.

Figure 1-17. Small arms and pyrotechnics.

Figure 1-18. Conning tower, looking aft.

Figure 1-19. Lower portion of a modern periscope.

The four main generators each produce 1100 kw. There are four main motors, driven by the generators or batteries, each producing about 1375 hp. The two reduction gears are of the herringbone, 2-pinion type and produce about 2750 hp at each shaft. The auxiliary engine is rated at 450 hp and drives a 300-kw generator.

The average fleet type submarine is capable of a speed of about 21 knots when operating on the surface and approximately 10 knots when submerged. This submarine has a cruising range in excess of 12,000 miles.

1D5. Ship's complement and ship's armament. a. Ship's complement. The personnel aboard the fleet type submarine range in number from 66 to 78. Officers number from 6 to 8, and men from 60 to 70.

b. Ship's armament. Torpedo tubes (figure 1-13) are the main offensive and defensive armament of the submarine. A total of 10 21-in. tubes are carried, six forward and four aft. Those shown in the illustration are No. 1 and No. 2. Located in pairs below tubes No. 1 and No. 2 are Nos. 3 and 4, and Nos. 5 and 6. The upper half of the No. 3 tube is visible in the lower right corner of the illustration.

Immediately above tubes No. 1 and No. 2 is the torpedo tube blow and vent manifold used for blowing or venting the tubes, WRT tank, and the trim tank. (See Figure 1-13.)

The rollers aft of the tubes and the racks farther aft (not shown in the illustration) are used for torpedo reload. The tubes can be fired electrically or by hand when surfaced or submerged. The condition of the tube is indicated by the torpedo ready lights, shown to the left of the No. 2 tube.

The 5"/25 deck gun (Figure 1-14) is a dual purpose gun. It is so mounted as to be used effectively against surface craft and aircraft. Two guns may be carried: if one gun is carried it is located abaft of the conning tower.

The 40-mm anti-aircraft gun (Bofors), shown in Figure 1-15, is mounted forward of the conning tower. It is principally an anti-aircraft weapon, but may be used against surface craft. It is a rapid fire, recoil type of gun. In some instances it is being replaced by a 37-mm gun. The 40-mm gun sometimes replaces two 20-mm guns.

The 20-mm anti-aircraft gun (Figure 1-16), sometimes referred to as the Oerlikon gun, is located either forward or aft of the conning tower on the bridge deck. It is a rapid fire, recoil type of gun. In some instances the single mount has been replaced by twin mounts. Four 20-mm guns are carried by the fleet type submarine.

In addition to the armament described above, the fleet type submarine carries other small arms and pyrotechnics (Figure 1-17). Chief among these are two 30-caliber and four 50-caliber Browning machine guns, and one 45-caliber Thompson submachine gun.

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