The strain was beginning to tell on everyone. Morris's crew had been "port and starboard" for almost a week now, four hours on duty, four hours off. Sleep patterns had been broken up. People didn't eat proper meals. Crucial maintenance requirements cut into what sleep allocations his men had. On top of that was the knowledge that a submarine or aircraft attack could come at any time. The work was still getting done, but Morris noted that his men were becoming terse and ill-tempered. People were beginning to trip over doorsills, a sure sign of fatigue. More serious mistakes would soon follow. The relationship between fatigue and errors was as certain as gravity. In another day or so he hoped a solid routine would establish itself, something for his men to adjust to. There were signs of this, and his chiefs were telling him not to worry. Morris worried.
"Bridge, Combat. Sonar contact, possible submarine, bearing zero-zero-nine."
"Here we go again," the conning officer said. For the twenty-fourth time on this voyage, Pharris's crew raced to battle stations.
It took three hours this time. No Orions were available for them, and the escorts pooled their helicopters to track down the submarine, an directed by Morris and his CIC crew. This submarine driver really knew his business. At the first suspicion that he had been detected-perhaps his sonar had detected a helicopter overhead or heard the splash of a falling sonobuoy-he went deep and began a confusing series of sprints and drifts, porpoising over and under the layer, working hard to break contact-toward the convoy. This one wasn't interested in running away. The submarine disappeared and reappeared on their tactical plot, always closing but never revealing his position clearly enough for a shot.
"Gone again," the antisubmarine-warfare officer said pensively. A sonobuoy dropped ten minutes earlier had detected a weak signal, held it for two minutes, then lost it. "This guy's beautiful."
"And too close," Morris said. If the submarine was continuing south, he was now at the edge of the frigate's active sonar range. Up to now, Pharris had not revealed herself. The sub's captain would know surface ships were about from the presence of the helicopters, but it wasn't likely that he suspected a frigate only ten miles south of his position.
Morris looked up at the ASW officer. "Let's update our temperature profile."
Thirty seconds later they dropped a bathythermograph probe. The instrument measured water temperature and reported it to a display in the sonar compartment. Water temperature was the most important environmental condition affecting sonar performance. Surface ships checked it periodically, but a submarine could do it continuously-yet another edge that went with a submarine.
"There!" Morris pointed. "The gradient's a lot stronger now and this guy's exploiting it. He's staying out of the deep channel, probably doing his sprints on top of the layer instead of under it where we expect. Okay..."
The helicopters continued to drop buoys, and the brief glimpses they got were of a target heading south, toward Pharris. Morris waited ten minutes.
"Bridge, Combat, left standard rudder, come to new course zero-one-one," Morris ordered, pointing his ship at the submarine's estimated position. The frigate was doing five knots, moving quietly on the calm seas. The CIC crew watched the heading readout on the aft bulkhead change slowly from the easterly heading.
The tactical display was useless. Confused by many brief reports from sonobuoys, most of which were probably false signals to begin with, the computer-generated estimate for the submarine's position covered over a hundred square miles. Morris walked over to the paper display in the after comer of the room.
"I think he's right about here." Morris tapped the chart. "Comments?"
"Running shallow? That's contrary to doctrine," ASW pointed out. Soviet submariners were supposed to stick with established doctrine, the fleet intelligence reports said.
"Let's find out. Yankee-search."
The ASW officer gave the order at once. Yankee-search meant turning on the frigate's active sonar and hammering the water to find the sub. Morris was taking a chance. If the submarine was as close as he thought, then he was advertising his own ship's location and inviting a missile attack that his point-defense systems were ill-equipped to stop. The sonar operator watched his screen intently. The first five pings came up blank as the sonar beam swept west-to-east. The next one painted a bright dot on the screen.
"Contact-positive sonar contact, direct path, bearing zero-one-four, range eleven thousand six hundred yards. Evaluate as probable submarine."
"Nail him," Morris ordered.
