Mersenne’s calculations also showed that cylindrical shapes could better withstand the water pressure at greater depths. As his research progressed, the mathematician concluded that the ends of a submarine’s hull should taper, to reduce drag and permit the vessel to reverse direction without having to turn.
Over the next few decades, Mersenne’s findings would do little to influence naval engineering. In the long term, however, all of his recommendations — from metal pressure hulls to tapered cylindrical hull shapes — would become standard principles of submarine construction.
CHAPTER 18
From his command chair at the focal point of Combat Information Center, Captain Zachary Heller swiveled to take in the video feeds from the topside camera arrays. Between the quarter moon and a sky full of stars there was plenty of ambient illumination for the cameras to operate in low-light mode.
If necessary, the cameras could shift to the infrared band, allowing them to “see” heat signatures even under conditions of total darkness. But staying in the optical band kept the image resolution much higher, and made the video displays more naturally intuitive.
Evolution had spent half a billion years creating and refining the sensory organs that led to stereoscopic vision in modern primates. Human beings were genetically wired to interpret images based on visual wavelengths of light. By contrast, the ability to understand infrared imagery was a strictly learned behavior, receiving no assistance from human instinct or biology.
Heller’s abba might disbelieve (or want to disbelieve) the teachings of Darwin, but Heller himself had no doubts about the realities of evolution. Natural selection had endowed the human animal with certain physical abilities and limitations. Like any military leader worth his rank insignia, he tried to factor human physiology into training scenarios and operational planning as much as possible.
In training situations, his standing order required the crew to work with the topside cameras in infrared mode at least eighty percent of the time, because reading the IR video displays took a lot of practice. During real-world operations, he preferred to keep the cameras in the optical band, where interpretation was instinctive.
It was a lesson he’d learned during his junior ensign tour aboard the old USS Gettysburg—train the hard way; do it the easy way. So far, that theory seemed to be paying off. The Bowie’s CIC team was nearly as proficient in IR mode as they were in optical mode, despite the limitations of human visual processing.
The Motor Vessel Lecticula was well outside of the shipping lanes, and running without lights. Probably the ship’s master didn’t hold any real hope of slipping past the blockade in the dark. He was a sailor; he knew that radar didn’t give a damn about darkness. More likely, it had been a purely reflexive decision. (If you’re trying to do something sneaky at night, you turn your lights off.)
Whatever the motivation might have been, the lights-out trick wasn’t working. The cargo ship was easily visible on radar, and she stood out just as clearly on display screen #3. In low-light mode, the cameras were limited to grayscale, but the clarity was exceptional.
On the video display, the MV Lecticula looked like exactly what she was: a poorly-maintained bulk cargo carrier, nearing the end of her operational life. And that end might be only minutes away if the ship continued to crowd the blockade line.
The Rules of Engagement were explicit. Ships approaching the blockade area were to be warned three times over bridge-to-bridge radio channel 16, which international law requires major vessels to monitor at all times. Any ship that failed to heed the radio calls would receive a single warning shot across the bow. If the would-be blockade runner continued to approach, it was to be engaged with naval artillery and either disabled or sunk.
Standing by for this task was the guided missile destroyer, USS Mahan, currently bearing 253 degrees from Bowie. The Mahan was interposed between the MV Lecticula and the do-not-cross line of the blockade area — positioned far enough back to stay out of the immediate blast zone in case the aging freighter suddenly went up in a nuclear fireball. Nobody wanted to be rubbing elbows with a nuke if the Lecticula self-destructed like her sister ship, the MV Aranella.
USS Bowie was in the backup position, lurking three and a half nautical miles behind the Mahan. If the old cargo ship miraculously evaded her more-nimble pursuer, the Bowie’s mission was to engage the target and finish the job.
A voice broke over bridge-to-bridge channel 16. It was the radio talker from USS Mahan, with the first warning call. “Motor Vessel Lecticula, this is United States warship Seven-Two. You are approaching an area under naval blockade. If you continue on your current course, you will be fired upon. If you approach within fifty nautical miles of the Cuban coast, you will be fired upon. You are directed to alter course immediately and depart the area.”
After fifteen or twenty seconds of empty static on the channel, another voice came over the radio, an interpreter aboard the Mahan repeating the warning in Korean.
There was no response. The Lecticula continued toward Cuba at eighteen knots.
The warning came again after a minute or so — first in English, then in Korean. Still no response. The freighter didn’t slow or turn.
“They’re showing us their game face,” Heller said. “My money says they’ll blow off the third warning too. They won’t turn until the Mahan drops a five-inch round across their bow.”
A few seconds later, a voice came out of a speaker in the overhead. Not the measured tones of the Mahan’s radio talker. A younger female voice, speaking over the Bowie’s 29MC antisubmarine warfare announcing circuit. “All Stations — Sonar has passive broadband contact off the starboard beam! Bearing two-nine-one with extremely rapid left bearing drift. Initial classification: POSS-SUB, confidence level low!”
Heller’s eyes flitted to the tactical displays. The new sonar contact appeared as a red line from the symbol representing USS Bowie to the edge of the display screen. The line was angled at 291 degrees: the current bearing of the possible submarine from Bowie.
Without echo ranging from active sonar, or a cross-fix from another sensor, there was no way to know the contact’s range. The possible sub could be anywhere along that line of bearing, from fifty yards to fifty-thousand.
Heller keyed his headset’s microphone. “Sonar, this is the captain. Is this our high-speed mystery contact? The one we were tracking on Sunday?”
“Captain — Sonar. Looks like it, sir. The broadband swath is so bright it’s nearly burning up our scopes. Extremely high bearing rate, and the audio sounds like a giant pan of frying bacon.”