As before, the convoy slowly approached Cheyenne while on board the submarine tubes one, two, and three were made ready to shoot once again. Designated as Masters 58, 59, and 60, three ships of the convoy-the two remaining troop transports and the merchant tanker-had been selected as the next targets.
Once again the firing procedures were executed by the numbers against Masters 58 and 59. The torpedoes from tubes one and two ran as expected and soon Cheyenne detected two more explosions under the last two troop transports.
The combat systems officer reported to Mack, "We're ready on Master 60, Captain."
Master 60 was the merchant tanker, no longer shielded by the troop transports. Mack knew that tanker would be sorely missed by the Chinese.
Mack glanced at the executive officer. "Very well, fire control. Firing point procedures, tube three, Master 60." Mack also knew that, with its single hull construction, the tanker would soon be spilling the diesel fuel, lubricating oil, and aviation fuel that the Chinese on the Spratlys really needed.
"Course of Master 60 is 195, speed ten, range fifteen thousand yards."
"Sonar, conn. Stand by."
"Conn, sonar. Standing by."
"Match sonar bearings and shoot, tube three, Master 60."
"Match sonar bearings and shoot, tube three, Master 60, aye, sir."
"Tube three fired electrically."
"Conn, sonar. Unit from tube three running hot, straight, and normal."
"Sonar, conn, aye. Time to acquisition?"
"Time to acquisition is-" The combat systems officer's report was suddenly cut off.
"Conn, sonar! We have torpedoes in the water off our port bow, SET-53s, bearing 205 and 207!"
Captain Mackey glanced quickly at the executive officer and then turned back to Cheyenne's control station. "Make your depth five hundred feet, increase speed to flank, do not cavitate. Release countermeasures." Mack then turned to look back at the executive officer. "Fire control, I need a solution on whoever that bushwacker is, and I need it fast. Cut the wire on tube three, shut the outer door, and reload tube three."
"Conn, sonar. I think we got it, sir. Must be a diesel boat since it was so quiet. But it's trying to reload and making a racket, bearing 200."
"Sonar, conn, aye. Snapshot, tube four, bearing 200, Master 61."
The Mk 48 from tube four was quickly on its way toward the bearing to Master 61. Mack would worry about the classification of Master 61 later.
"Conn, sonar. Both enemy torpedoes have increased speed"-the sonar supervisor paused-"but they are on intercept course for our decoys," he added. "They fell for it."
But Mack wanted one more piece of news before he was sure that the danger had passed. "Sonar, conn. What course are those torpedoes on?"
"Conn, sonar. Course is 020. They are headed out and away, sir. No indication of re-attack."
The immediate threat of the torpedoes had passed, but Cheyenne wasn't out of danger yet. The submarine that shot them was still out there.
But not for long. The Mk 48 from tube four acquired the enemy submarine, and minutes later sonar reported an explosion from the bearing of the fleeing diesel. Master 6 i, which had given itself away as a noisy Romeo as it increased speed, was no longer a threat.
But Mack didn't relax. Cheyenne still had a job to do. "Sonar, conn," he said. "What's the surface picture look like?"
"Conn, sonar. The remaining ships of the convoy are still on same course, same speed. Master 60, the tanker, is no longer with the convoy; it's fallen astern of the convoy. Sounds like it's dead in the water, Captain." The BSY-I operators confirmed the sonar supervisor's call.
"Sonar, conn, aye. What about the escorts?"
"Conn, sonar, the escorts are still on station, but I…" The sonar supervisor's voice trailed off.
That was unusual. "Conn, sonar, go on," Mack said. "What is it?"
"Conn, sonar. I could swear that I heard another torpedo and some other explosions in the direction of the convoy. Almost like they were attacking another submarine."
Mack paused. There were no friendlies in the area, so what could they have been attacking? "Sonar, conn. Did it sound like they got anything?"
"Conn, sonar, no, sir. But I was kinda preoccupied, Captain."
Mack smiled to himself. "Sonar, conn, aye. We're going back after the convoy. Get a clear picture, sonar."
"Conn, sonar, aye."
"Captain. What about the cripples?" the combat systems officer asked. "Are we just going to leave them?"
"That's exactly what we're going to do. Our job is to stop a convoy, not rack up a tonnage score. And your job," Mack added, "is to get me firing solutions on three more convoy ships,"
"Aye, aye, sir," the combat systems officer said.
That diesel submarine bothered Mack. The question that kept coming back to him was how did that diesel know Cheyenne was there? A diesel boat couldn't keep up with the convoy while submerged, and the odds of Cheyenne running into a diesel like that by coincidence right in the middle of the convoy route were simply astronomical.