THE “NARVAL” IN THE “AWASH” CONDITION.
The Narval in June, 1901, made the experiment of remaining for twelve hours under water.
The Ministry of Marine were represented by Naval Surgeon Gibrat, who wrote a full and detailed report on the condition of the crew after their twelve hours’ submersion.
From notices published in the French papers it would appear that “the trial succeeded without incident,” but the impression seems to be general that the crew were in a more or less exhausted condition after their prolonged sojourn beneath the waves, which after all is not to be wondered at.
It appears that after six hours under water the inhaling of artificial air became difficult; the long exclusion of natural atmosphere caused a painful irritation of the nerve centres which even the coolest of the officers could not resist, and anæmia set in accompanied by cerebral compression and sick headache. Trouble was also caused by the working of the accumulators, which liberated among the crew salts of lead and sulphur, causing digestive and intestinal complaints. Dr. Gibrat is reported to have expressed to them that, in the present condition of knowledge, 12 hours is the outside limit of efficient work on a submarine under water.
The Narval class, besides the eponymous vessel, comprises four other submersibles—the Sirène (launched May 4, 1901), the Triton (launched July 13, 1901), the Espadon (launched August 31, 1901), and the Silure (launched October 29, 1901). These four resemble the Narval in most particulars, though in some respects they are improvements on their prototype.
The outer hull of each is made of steel, but the inner hull is made of nickel steel. The choice of the metal is a matter of importance, for the difficulty is to build a hull which possesses sufficient strength to resist the pressure of the water, and yet at the same time is not too expensive. Between the two hulls in the interior of the vessel are seven compartments for water ballast. There are also four water tanks, which are used to regulate the trim of the vessel by introducing water at the last moment.
The inconvenient points of the Sirène and her sister vessels are the same as those of the Narval. A few minutes are sufficient to fill the water-ballast compartments, but, according to a recent article in La Patrie, it takes a good half-hour to empty them in order to rise to the surface. The operation is begun with compressed air, and continued with a pump worked by electricity. For steaming on the surface of the sea the Sirène uses a triple-expansion engine and a Normand boiler heated by petroleum. For submarine navigation she uses two dynamos connected with the main shaft. These dynamos recharge the accumulators, which are on the Laurent Cely system, in less than 7 hours. The vessel can steam on the surface 21 hours at 12 knots with the petroleum engine, and 625 miles at 8 knots. Under water, making use of the accumulators, she can do 25 miles at 8 knots, or 70 miles at 5 knots. Her armament consists of four torpedoes 17¾ inches in diameter, which are fired by the Drzewiecki system. As the torpedoes are placed on the deck, the vessel must be under the water in order that they may be fired. The crew consists of twelve men, including the lieutenant commander and his sub-lieutenant.
The Sirène recently underwent a 24 hours’ trial at Cherbourg. Twenty hours were devoted to evolutions on the surface, and the remaining four hours spent under water.