National Geographic : 1952 Nov
Our Navy's Long Submarine Arm Snorkel-equipped Prowlers Bring a New Era, and the Atomic Sub Now Being Built Promises a Far Greater Undersea Revolution By ALLAN C. FISHER, JR. r' IAKE her down!" Ah-ooo -ga! Ah ooo-ga! Two blasts of a raucous horn signalled the command. Men who had been stationed on the bridge of the U. S. S. Sablefish plunged down the conning tower hatchway like rabbits jumping into a hole. The last man slammed and locked the hatch. For nearly an hour our submarine had been cruising on the surface off New London, Con necticut. Now, with the sounding of the diving alarm, we were about to submerge for a test of her snorkel, the ingenious breathing tube that enables today's deadly steel sharks to remain underwater for weeks at a time. Three Weeks Under the Sea The snorkel, a Dutch invention perfected by the Germans, luckily was not quite ready to be unleashed against Allied shipping in World War II. Simple in principle, it con sists of two pipelike cylinders. One sucks in air from the surface, while the other expels engine exhaust into the water. "Snorkel," a postwar addition to the dic tionary, is generally supposed to come from the German Schnorkel, meaning spiral or twisted ornament. Another version is that it stems from the colloquial German word Snorchel, meaning animal's snout. The Brit ish call the device a "snort." Until the snorkel revolutionized submarine warfare, Diesel engines, requiring air, could not be used when the boat was submerged. To recharge batteries needed for underwater pro pulsion, the submarine had to surface fre quently. Now, with the snorkel, Diesels can be run at periscope depth. Batteries, still needed for deeper operation, can be charged without venturing up to the open air. Thus the modern submarine can stay sub merged for many days, greatly increasing its chances of avoiding detection. World War II subs, when surfaced, often were easy radar targets. The snorkel breathing-tube head, however, is no bigger than a cottage chimney. U. S. Navy. Olicial + A Destroyer Escort Lays Down a Rosette of 17 Depth Charges In two world wars depth charges had a demoraliz ing effect on U-boat crews. Deadly "ashcans" shook submarines violently, though they often failed to destroy their targets. The hedgehog, a newer weapon, has proved more effective (page 626). It is hard to detect, particularly in a rough sea. One of our Navy's snorkel submarines, the Pickerel, has cruised all the way from Hong Kong to Pearl Harbor, Hawaii, without once coming to the surface in 21 days and 5,600 miles. Although the cruise underscored the new elusiveness of the submarine, it was undertaken primarily as a test of equipment and, above all, men. "Snorkeling" creates serious physiological problems for crewmen. The air-intake valve, when struck by a wave, closes automatically to prevent flooding. But the Diesel engines keep gulping air like a vacuum pump until the snorkel is clear and its valve reopens. This results in rapid variation of air pres sure within the submarine. Crewmen some times experience an uncomfortable ear-pop ping, head-filling sensation, though in time they become conditioned to it and simply ignore the occasional discomfort. I was to find out for myself what a headache snorkel ing can be. 20 Minutes Enough for a Landlubber As the Sablefish nosed under, I could feel the deck tilt slightly. There was no other sensation to indicate we were slipping beneath the waves. Once submerged, nothing I could detect suggested our forward motion. Climbing to the conning tower, I joined Comdr. Julian T. Burke, the sub's skipper, at the periscope. Above us the day was over cast and mild, with just enough sea swell to give the air induction valve a good workout. An order sent the hydraulically operated snorkel tubes to the surface. "Now watch the altimeter," Burke said. In a fraction of a minute the gauge needle swung to 800 feet. A command for more power went to the engine room, and the needle crept higher, to 900 feet, 950, then 1,000. Our huge Diesels were eating up air within the submarine, whisking us from sea level to rarefied mountain atmosphere. When waves closed the snorkel valve, the altimeter raced higher and the temperature in the submarine became noticeably cooler. When the valve opened, the needle fell and the air turned humid. My ears ached like a bad tooth until Burke suggested, "Hold your nose and blow. It will open up your head."