There’s not much in the way of interesting scientific anniversaries on my list for this month, which suits me fine, because it means I can focus on the one that interests me most: the 40th anniversary of the launch of the world’s first nuclear submarine, the USS Nautilus, on January 21, 1954.
I don’t know why, but submarines have always fascinated me. Maybe it’s because I’ve lived my whole life on the prairies, as far as you can get from an ocean, which lends the sheen of the exotic to anything to do with the seas. Maybe it’s from early exposure to the old television series Voyage to the Bottom of the Sea (recently reincarnated, for all intents an purposes, as Sea Quest DSV) and Jules Verne’s novel 20,000 Leagues Beneath the Sea. Whatever, the 40th anniversary of the launching of the Nautilus seems an excellent opportunity to pursue my submarine interest.
Submarines have been around a surprisingly long time. Cornelius Drebbel, court engineer to James I of England, demonstrated an underwater vessel on the Thames way back in 1620. It was propelled by oars sealed at the locks by leather gaskets, and submerged (as far as we can tell) by letting water into the hull, then surfaced by pumping it out again (and crewed, one hopes, by volunteers!).
That’s still the way submarines do it today, although with greater sophistication. Submarines consists of two hulls, an inner one containing air, called the pressure hull, and an outer one. The space between the two is filled with ballast tanks, which are flooded with water to make the sub sink and pumped full of air to make the sub rise.
A submarine is thus a perfect example of Archimedes’ Principle, which states that an object in a fluid will rise if the amount of fluid it displaces weighs more than it does, and sink if the amount of fluid it displaces weighs less than it does. It stabilizes at a point at which the amount of fluid it displaces weighs exactly the same as it does. Submarines control their depth by matching their weight to the weight of the water they displace
The second submarine of note, the Turtle, added another innovation: propellers. Designed by David Bushnell while he was a student at Yale (those crazy engineering students!) and launched during the American Revolution, it was a one-man craft shaped sort of like a fat barrel. A complex system of valves, air vents and pumps controlled its rising and sinking, and propulsion came from two sets of hand- and foot-cranked propellers: one set to drive it forward and one to move it up and down. On September 6, 1776, Sgt. Ezra Lee piloted the Turtle out to the British flagship Eagle off New York and attempted to attach a mine to it with an auger. Unfortunately (or fortunately, depending where your sympathies lie), the auger couldn’t penetrate the Eagle‘s copper sheathing. Lee jettisoned the mine and no damage was done.
The nuclear Nautilus was named that for a good reason: the first practical submarine was also named Nautilus. Robert Fulton (of steamboat fame) demonstrated it to the French navy in 1800 and 1801. Compared to the crude Turtle of just 25 years before, it was a modern marvel. Made of metal, it carried four men, could stay underwater for six hours, had a streamlined fish shape to reduce water resistance, used water ballast tanks to raise or lower the craft, and was propeller-driven–although, there being no practical underwater power source yet, the propeller, like the Turtle‘s, had to be cranked by hand. However, for surface travel, it carried a collapsible mast and sail.
The Nautilus added one more important innovation: horizontal rudders, or diving planes, to control the angle of the sub’s ascent or descent. With that addition, the elements of the modern submarine were all present. However, none of the governments Fulton demonstrated the Nautilus for were convinced, and so he dropped the project.
The Nautilus was designed to tow a mine that could be brushed up against an enemy ship: from the beginning, submarines have been seen primarily as military vessels. To the Confederates in the U.S. Civil War went the dubious honor of being the first to actually sink a ship via submarine: the hand-cranked sub Hunley carried a “spar torpedo”–an explosive charge on the end of a six-metre pole. It succeeded in sinking the USS Housatonic off Charleston on February 17, 1864, but destroyed itself in the process.
World Wars I and II brought fleets of more-and-more-advanced submarines into the world’s oceans. Electric motors finally provided a suitable underwater power source, although batteries had to be recharged frequently by extended surface travel using diesel engines. That’s why submarines of the two world wars still had the shape of surface vessels, with sharp prows and long, slender hulls.
The nuclear Nautilus had those features, too, because that’s how the U.S. Navy knew how to build submarines: but the nuclear Nautilus spelled the end of the days of extensive surface running.
A nuclear-powered sub contains a small, well-shielded nuclear reactor that creates intense heat, which is used to generate steam to turn propulsion turbines and supply electricity for all the subsidiary systems. Because nuclear power does not require oxygen and produces no noxious fumes, it puts no strain on the submarines’ air supply. In fact, it powers devices which turn seawater into fresh water and oxygen.
That means that a nuclear submarine’s range is practically limitless. The Nautilus sailed 170,000 kilometres, 146,000 of them submerged, before refueling, and on August 3, 1958, even sailed under the Arctic ice and the North Pole. In 1960, a second-generation nuclear sub, the USS Triton, sailed around the world, entirely underwater, in just 84 days.
Without the need for frequent surface running, modern nuclear submarines have teardrop-shaped hulls that provide the maximum streamlining for underwater travel: and allow speeds of up to 30 knots, fast even for most surface ships.
The Nautilus pointed the way, for good or bad, to today’s world where fleets of submarines carrying enough nuclear missiles to destroy entire countries are continually at sea, but with its trip under the Arctic ice, it also showed how submarines could be used for scientific research.
Here’s hoping the future focus is on submarines more for the latter purpose than the former.
