The door opened after a quick knock. One of Alvarez’s security men stepped in. In the hall stood two men in suits, both Anglos. Their jackets were unbuttoned for quick access to what was undoubtedly on their hips.
“Mr. President,” the CFS security man began, looking directly at Alvarez. “It is time.”
José-Ramon Alvarez smiled at the somewhat early use of the title that would soon be officially his. It would take very little getting used to.
It was the beginning of a catastrophic failure.
The USS Pennsylvania, an Ohio-class ballistic-missile submarine, was arguably the most complex platform in the arsenal of the United States for the employment of strategic nuclear weapons. On board she carried a mix of sophisticated sensors, machinery, and weapons, all of which worked in harmony to make the eighteen-thousand ton sub a silent and potent deterrent to aggression against the country she served. Costing more than a billion dollars, the Pennsylvania was a reliable boat but one that required regular maintenance to ensure her effectiveness. Everything that could be done to keep her in tip-top shape was.
But there had been a mistake.
“Cap’n, that harmonic is gettin’ worse,” the chief of the boat reported.
The Pennsylvania’s captain finished his notation and snapped his personal logbook closed. A gift from the crew of his old boat, the last Lafayette-class boomer to be in service, the waterproof box, slightly larger than a clipboard and an inch thick, had the name of his present command stenciled boldly across its front. He sneered at the reminder. The Pennsylvania, despite being the most advanced inhabitant of the aquatic world, had been nothing but a pain in the ass this cruise.
“Still the shaft gears?”
“Aye, sir.”
The Pennsylvania, like all submarines in the U.S. inventory, was powered by a nuclear reactor, a General Electric S8G natural-circulation model in this case. But unlike other submarines, the propeller shaft of the Ohio class had no direct mechanical contact with the steam turbines. These were turned by steam produced when water in the “cold” loop passed through heat exchangers, which transferred thermal energy from the superhot reactor by way of the circulation of coolant through the “hot” loop. This two-loop system isolated the “hot” radioactive coolant. The turbines, instead of transferring their circular motion directly to the shaft by way of lifter rods or gears, turned an electric generator, which powered a quiet electric drive system that drove the propeller shaft. The process, known as turboelectric drive, was highly efficient and exceedingly quiet, a must for survival in the life of a boomer, whose mission was to go to sea and cease to exist.
But it was that search for silence that had begun a series of events the result of which would soon manifest itself.
During the Pennsylvania’s last refit, completed two months earlier, the gear assembly that transferred power from the electric motor to the shaft had been replaced with newly designed ones that had proved less prone to harmonic transmission — the propagation of even the slight machinery sounds from the electric motor through the shaft and into the water. The new gears used a unique sound-dampening system of assembly to cut the sub’s acoustic signature a further 10 percent. The twin cylinders of high-stress alloy into which grooved channels had been machined were basically reengineered into twelve “slices” of gears that fit together over a main connecting core made of a layered combination of titanium, ceramic laminates, and more titanium. Each slice was fit over the core in sequence, and in between each was a gasket made from a carbon-fiber laminate, which was the true trick of the new assembly. Quite literally, they cut the transfer and reflection of sound from gear to gear, and thus helped remove a source of harmonics that had plagued all subs for decades.
Key to the successful use of the new system was its proper installation and maintenance, and the crew of the Pennsylvania had done well following every safety and operations check the assembly required. But there was one thing they could not check, as it was an installation item, designed to be configured during refit and left alone until the sub’s next stay in port.
Holding the twin gear assemblies — one lay on each side of the similarly geared propeller shaft — tightly together as one unit was a single twelve-inch nut at the aft end of each cylinder. This nut was set and torqued during refit according to a very tight tolerance, as even the barest variance could negate the positive effects of the system and actually add to the problem of harmonic transmission. But the nut on the starboard assembly had not been torqued properly — it was recessed inside the aftmost gear by almost six inches. The technician responsible for its installation had added four-and-a-half foot-pounds too much torque when mechanically tightening the fifty-six pound nut. That alone was enough to cause an excess of harmonics because it compressed the composite gaskets too tightly and degraded their sound-dampening qualities. But in combination with another phenomenon, one the crew of the Pennsylvania had no control over, the error was about to prove deadly.
Traveling on a course of three-four-five, skirting the Bahamian Island chain to port on her way to the relatively feature-free Blake Plateau, the Pennsylvania, running at six hundred feet, was in the midst of the Gulf Stream, which flowed northwest along her route to King’s Bay, Georgia. Sixty miles off the island of Eleuthera, in a water depth that exceeded fifteen thousand feet, the warm current was moving at more than five knots, a direct result of the exceedingly hot winter months the Southern Hemisphere was experiencing. This warm water rushed northward, and was, at the moment, giving the Pennsylvania a much appreciated “tailwind” that turned her self-produced twelve knots into a nature-aided seventeen. It was also doing something else.
The huge bronze propeller at the rear of the sub was absorbing tremendous punishment — which it had been designed to accept — from the unstable water it was churning. The five-knot current was acting upon the water propelled aft and away from the sub, creating a doughnut-shaped area of lower than normal water pressure nearer the ends of the propeller’s seven blades. As they turned, they were alternately “sucked out,” away from the sub into the pressure void, then pushed back as they found “clean” water. This fluctuation was not an entirely abnormal phenomenon, but it was very powerful. The motion was transmitted inside the submarine through the shaft to the gear assembly, which rested upon a sound absorbing sheet of high-density voided polymers. The assembly actually moved the few millimeters with the shaft. Back and forth. Back and forth. The motion was barely perceptible to the human eye and raised no alarm with the sensitive instruments that monitored all facets of the sub’s propulsion system.
But it did register on the nut that had been torqued beyond spec. The repetitive motion, driven by tons of force, was transmitted to the nut that had lost much of its ability to absorb such fluctuations. As the geared cylinders spun with the energy of more than thirty thousand shaft horsepower, additional stresses were placed upon the nut that held the twelve slices together. At full speed the effect would have been similar to that of a jackhammer with the shaft snapping in and out in fractions of an inch while the gears absorbed the punishment. This took longer. After an hour in the current the nut developed a tiny hairline fracture on its inner face. Ten minutes later the fissure had spread through the nut. A minute after that it separated in two with a loud snap that caused heads farther forward in the engine room to turn. The pieces came free of the core that ran the length of the gear assembly and spit aft, impacting the bare metal bulkhead. Less than a second after that the aftmost gear slice, following its natural rotation and now free to move, slid off the core, spinning with a force unimaginable.