Steadying himself on the ladder rungs, Tremain yelled down the hatch to the control room, “Take her down to sixty-five feet!”
“Sixty-five feet, aye sir,” came the reply from Olander, now standing at his battle station as the diving officer. He stood behind the two planesmen in the control room and directed them as they pulled and turned on their controls to reach the ordered depth.
Tremain watched the depth and speed gauges in the conning tower as Mackerel slowed and leveled off at her new depth.
“At sixty-five feet, Captain,” Olander called back up the control room hatch.
“Very well, Dive,” Tremain replied. “Helm, all ahead one third.”
Tremain knew they were well ahead of the freighter now. If the freighter held course and speed it would pass directly in front of them, lining up perfectly for the coveted beam shot desired by all submarine captains. He only hoped that Mackerel was still undetected. The next periscope observation would tell.
Tremain noticed Cazanavette hovering over a ship identification book laid out on the small chart desk.
“Did you get a good look at her, XO?”
Cazanavette nodded without taking his eyes from the book, then slapped his finger on the opened page.
“That’s it,” he said. “The Mirishima Maru. Fifty-three hundred tons.”
Tremain looked at the black silhouette on the page. The two masts, the short smoke stack, the raised superstructure. It was almost certainly the same ship he had seen plowing the seas above them. The book gave several dimensions on the freighter. Tremain noted the mast height and pointed it out to Petty Officer Smithers, the periscope assistant, who quickly wrote it on the back of his hand. Smithers would need the mast height to read ranges off the stadimeter mounted on the back of the periscope.
Tremain looked at the clock. It had taken several minutes to submerge and to stabilize. The freighter would have closed the distance considerably in that time.
“What’s the generated range and bearing to target now?” he asked.
“Four thousand five hundred yards, bearing three zero zero,” Hubley said, reading the information off the TDC.
Tremain closed his eyes to get a mental image of what he should see through the periscope.
“Up scope,” he ordered.
Smithers raised the number one periscope and Tremain met it at the floor, slapping down the handles as it rose out of the well. As the ocean spray cleared off the lens, Tremain conducted a quick sweep of the horizon. Satisfied that there were no other contacts, he focused the scope down the expected target bearing. Between wave slaps he saw the freighter’s starboard bow move slowly across the field of view. It was harder to see it now over the waves because, at Mackerel's current depth, the scope lens just barely poked above the surface of the water. Most of the hull was beyond Tremain’s visible horizon. He turned the handle to increase the magnification and lined up the reticle on the freighter’s smokestack.
“Bearing.. mark,” he called.
“Three zero five.” Smithers read the bearing from the compass on the scope well.
It was only five degrees off from the bearing Hubley had taken from the torpedo data computer, so the solution had to be very close to the freighter’s actual course and speed.
“Range … mark.”
“Four thousand yards.” Smithers read the range from the stadimeter scale.
Hubley entered the data into the TDC and within seconds came back with a reply. “Observation checks with the solution in the TDC, Captain.”
Tremain smiled. The freighter had not changed course or speed. It meant that Mackerel had not been sighted. As he rotated the scope to the left, he caught a glimpse of a smaller ship coming up rapidly on the freighter’s starboard quarter. Tremain did not need the identification book to recognize it, for he had seen its type many times before. It was a destroyer escort of the Matsu class, plodding the water at nearly twenty-five knots. He could easily make out its ominous five-inch gun turret directly forward of the squatty bridge structure. He could not see it, but he knew that the escort carried a similar gun on its stern.
“Matsu escort,” he said for the benefit of the men in the conning tower. “It should pass by before we get to our firing position. Down scope.”
Tremain slapped up the handles as Smithers lowered the periscope.
As Mackerel moved along at three knots to close the range to the freighter’s track, Termain weighed his options. He could try to sink the Matsu first. Then, with the escort gone, he could destroy the freighter at his leisure. However, a Japanese Matsu class destroyer escort was fast and maneuverable. It was fast and maneuverable enough to avoid a Mark 14 torpedo if it saw it coming in time. If he fired at the destroyer escort first, he might get a hit, but most likely the Matsu would evade and follow the torpedo wakes right back to Mackerel's position — forcing Mackerel to go deep and allowing the freighter to escape unmolested. The attack would be a complete failure and the crew would lose whatever confidence they had left. The choice was suddenly clear to him. This crew had to sink a ship. Tremain decided that the freighter would be his one and only target. He would concentrate all efforts on sinking it.
Cazanavette was obviously weighing the same options in his head. He carefully worded a question — to evidently feel out Tremain. “Do you plan on shooting on the generated solution, sir? We might be able to get in one more good observation.”
“One is all we’ll need, XO. That freighter has not zigged for hours. He’s just heading straight for Truk as fast as he can. The TDC solution should be a good one. I’ll take one more observation at time of fire.”
Tremain turned to Smithers, who had a sound-powered phone hanging around his neck. The young sailor looked nervous, but he was intently listening to Tremain’s every word.
“Pass to the forward torpedo room,” Tremain said to him. “Open outer doors on tubes one through four and make the tubes ready for firing in all respects. Set depth at eight feet.”
As Smithers relayed the orders to the torpedo room, Tremain exchanged glances with Cazanavette. The moment they had been waiting for was fast approaching. They would be firing the specially modified torpedoes. Soon they would know if Konhausen’s modifications had fixed the detonators, or if Tremain had just ruined his career for nothing. Tremain gathered from Cazanavette’s expression that he inwardly wanted the torpedoes to fail. Then he would be proved right.
Several minutes passed before Smithers received and relayed the report that tubes one through four were ready. Joe Salisbury, manning the sound gear, reported high speed screw noises correlating to the Matsu. It was passing across Mackerel’s bows, from port to starboard. Salisbury estimated its range at only one thousand yards.
“Generated distance to the freighter’s track, fifteen hundred yards, Captain,” Hubley reported as the TDC ticker hit fifteen hundred.
Tremain took a deep breath. Mackerel was only making three knots of headway, but he still was not sure whether the Matsu would be close enough to see the telltale periscope ‘feather’ on the surface. He noticed that his palms were sweating. The time had come.