SSN - Tom Clancy [6]
For her transit to Pearl Harbor, Cheyenne was given a small loadout of torpedoes. The full capability of her torpedo room was twenty-six weapons, including four in the torpedo tubes, consisting of a combination of Mk 48 torpedoes, Tomahawk cruise missiles (land-attack and anti-ship varieties), Harpoon antiship missiles, and sometimes, though rarely, Mk 67 submarine-launched mobile mines. However, for this transit, Cheyenne was given only 12 Mk 48 ADCAP torpedoes. With a top speed of over fifty knots while running deep, and a range in excess of 30,000 yards, the Mk 48 ADCAP was arguably the best heavy torpedo in existence. Its only real competition came from the British Spearfish, which was carried by the submarines of the Royal Navy.
The Mk 48 ADCAP, which stood for Advanced Capability, was a heavy wire-guided torpedo weighing over 3,000 pounds. Nearly 20 percent of its weight, or 650 pounds, consisted of PBXN-103 high explosive. One of the advantages of the Mk 48 was that it could be used against both submarine and surface targets, which made it much easier on logistics. It also pleased many submarine captains who still preferred the thrill of launching a torpedo over the newer, vertical launch Tomahawks or encapsulated Harpoon missiles.
Each Mk 48 was wire guided so that targeting data during the initial stages of the torpedo launch could be transmitted back and forth from the Mk 48 to the BSY-1 fire-control system on board the attack submarine. During the terminal stages of the attack, the Mk 48 would use its powerful active seeker to detect, home in on, and then destroy its target. As long as the wire was intact, information from the torpedo was constantly relayed to Cheyenne until detonation.
After the meeting, Mack returned to the control room. Knowing that there might be a nuclear attack submarine in the area, he ordered that instead of running at twenty-six knots for much of the way to Pearl Harbor, as he had originally planned, Cheyenne would now slow more frequently in order to listen to her surroundings. This "sprint and drift" technique was one of the best methods of arriving at a destination quickly while also allowing the submarine's passive sonar to search for any possible sonar contacts.
Cheyenne was now at an ordered depth of four hundred feet. At this depth, she was in her own element, that of the depths of the ocean. If necessary, she could still be reached by the relatively new, albeit slow, ELF, or extremely low frequency, band of communications. If there were a dire emergency, or a change in her orders, Cheyenne would be instructed by a short, coded ELF message to come to communications depth in order to receive important message traffic.
Running at twenty-six knots was not always quiet. The screw, known to those outside the Navy as a propeller, was working feverishly to propel the submarine at this speed. If too shallow, this created tiny air bubbles, which made a popping noise when they collapsed. This noise was known as cavitation and could give away a submarine's presence in the area. At this moment, Mack did not care as much about his stealth capability as he did about two other concerns: locating the submarine that was lurking dangerously near the West Coast, and arriving at the Pearl Harbor Naval Submarine Base with Cheyenne intact.
All aboard Cheyenne were aware that they were making slight cavitation noise and that anyone who was close enough and quiet enough could determine their location. The frequent slowing and so-called clearing of the baffles, the normally "sonar blind" area astern of submarines, evened the score somewhat.
At 1100 on 12 August, just ten hours after leaving San Diego, the OOD ordered Cheyenne to slow to one-third. Exactly eleven minutes