Please read this:
By the mid-1890s, however, a practical submarine appeared to be within reach. In 1896, the French Minister of Marine announced an international competition for submarine designs. The specifications stipulated a vessel with no more than 180 tonnes (200 tons) displacement, a cruising range of at least 160 kilometers (100 miles), a speed on the surface of 22 KPH (12 knots), and a speed underwater of 15 KPH (8 knots). At least 29 designs were submitted for the competition. The winner of the competition was a breakthrough design named the NARVAL, built by a Frenchman named Maxime Laubeuf. The NARVAL was launched in 1899.
The 34 meter (111 foot 6 inch) long NARVAL had two propulsion systems, a 220 HP oil-burning steam engine for surface running, and an 80 HP electric motor for underwater propulsion. The NARVAL could cruise on the surface for up to 800 kilometers (500 miles) at 15 KPH (7.5 knots), or up to 400 kilometers at 20 KPH (11 knots). She could cruise underwater for 40 kilometers (25 miles) at 15 KPH, or 115 kilometers at 9 KPH (5 knots).
The most important feature of the NARVAL's propulsion system was that the steam engine could recharge the batteries for the electric motor while the vessel was under way on the surface, running the electric motors in reverse so that they would act as dynamos. This clever and efficient scheme would be the basis for later submarine design. The propulsion problem was not entirely solved, since a steam engine tended to be too hot to put inside a small and cramped submarine, and shutting down the burners for submergence and then trying to build up a head of steam again after coming to the surface was far too time-consuming.
The NARVAL was one of the first double-hulled submarine designs, with an inner hull that held the crew and an outer one that contained ballast tanks. Such a double-hull design was extremely strong, and did much to improve the reliability of submarines. Four torpedoes were carried in external tubes, two on each side of the prow, which was fitted with a ram. Diving remained a difficult and tedious procedure. Despite its defects, the NARVAL was close to the right answer. However, at the same time, two American inventors were developing submarines that were at least or even more advanced.
A speed of 11 knots is obtained at the surface, and 8 knots when submerged . A new departure in the " Narval " is her double hull, the inner shell of which is of steel plate of sufficient thickness to resist any water-pressure to which the boat may be subjected, and the outer shell, placed at varying distances from the innerprotection to the inner against attack . An armoured of the ship doomed to destruction . Retiring then to a safe distance, the submarine boat could explode the torpedo by the agency of an electric current . Working in the light of his now considerable experience, M . Goubet built several other boats . These were of larger dimensions, having a length of 27 ft.; their material was also bronze, and they were cast in three pieces, the centre one having a thickness of 1 in., while the others were reduced to a little more than 1 in. at the ends . Possessing to a large extent the same contrivances as their predecessor, these improved boats were fitted also with an automatic apparatus for regulating the depth of submersion . In this regulator a piston is moved along a cylinder by the rotation of a rod with a screw thread cut in it, and so increases or diminishes the amount of water in the cylinder . The movement of the piston is effected by a small motor, and the direction of action of the motor is regulated by a commutator placed in juxtaposition to a pressure gauge . When the depth of submersion is too small, current is supplied to move the piston so as to admit more water; when the depth is too great, current is supplied in the opposite direction, and water is expelled . The speed attained by this boat was from 5 to 6 knots .
Smaller boats of this type have been built for propulsion by manual power, but, however perfect the mechanism, the range of action of a submarine dependent on man-power for propulsion is very limited . Recent Goubet boats are being built; with motive-power, which it is proposed to carry on board ship and lower from davits when required . The "Gymnote " was constructed Toulon in 1888 . She is a steel vessel, with a length of 59 ft. and a displacement of 30 tons; being of an experimental character only, she has no weapon of attack . The maximum speed obtainable is 8 knots . The designs of the " Gustave Zede " and of the Morse " were both based on those of the " Gymnote," the former having a length of 148 ft. and a displacement of 263 tons . In both of these the hull is of bronze; one great advantage of this metal being that, like the bronze of the Goubet boats, it is non-magnetic in character, and cannot therefore disturb the equilibrium of the compass . With their large dimensions they were intended to be formidable engines of war, and were furnished for attack with Whitehead torpedoes; of these tatter they each carry three of 45 cm . (nearly 18 in.) diameter, discharging them by means of a torpedo tube . The " Morse " and the " Gustave Zede," like the " Gymnote," possess only electric means of propulsion, the power being derived from batteries of accumulators . No power is provided in the vessels by which the accumulators can be recharged, so that the radius of action of these boats is necessarily very limited .