“Shut the induction,” said Taylor. The chief flipped the switch. One of the two circles vanished, was immediately replaced by another of the dashes. The two men continued to watch the panel, relaxed ever so slightly when the last circle changed to a dash. “Straight board, sir,” said the chief to Taylor, unnecessarily loudly because Taylor was standing right beside him, and unnecessarily in any case since Taylor was also looking at the board. But again, this was part of the routine. Not only was Keith in the control room, so were a dozen other members of Cushing’s crew. All of them were vitally interested in the proper conduct of a dive.
“Open the vents,” said Taylor. The chief’s practiced fingers flew across another row of switches on his console. A series of red dashes in a second indicator panel changed to circles, and simultaneously a faint noise of rushing air could be heard. A pair of khaki-clad legs appeared in the bridge access trunk, followed immediately by dungaree-clad legs. Their owners, similarly garbed in dark green foul-weather parkas, with faces reddened from the exposure to the elements like those of the lookouts preceding them, stepped into the operating area around the diving panel.
“Hatch secured,” the one in khaki said to Taylor.
“Aye,” responded Taylor. “I’ll take the dive, Howie.”
“All right. I’ll pass the conn over to you after you get her under.” Turning to Leone, the officer of the deck said, “Bridge secured, Captain. All clear topside. We’re still on the same course, one-two-five true, speed fifteen. I’ll pass the conn over to Curt as soon as he’s ready.”
As Keith acknowledged the formal report from Lieutenant Howard Trumbull, officer of the deck, he could feel the slight downward inclination of the submarine. Bow and stern planesmen were sitting in their seats near the forward bulkhead of the control room, facing an impressive array of dials in their carefully designed instrument panel. Extending from the floor between the legs of each was a stubby column topped with a steering wheel minus its top quadrant, patterned after the control columns in aircraft and designed to fill almost the identical purpose except that they could be, and frequently were, operated independently. The man on the left, in fact, had already pushed his control column forward. “Stern planes on fifteen dive,” he said to Curt Taylor, who had moved over and was now standing behind him.
“Three degree down bubble,” said Taylor. He turned to the man operating the right-hand column. “Put your sailplanes on full dive,” he directed. Obediently, the man pushed his control stick all the way forward, held it there.
The deck tilted farther under Keith’s feet. There was more sound of air venting from the ballast tanks. The depth gauge quivered, began to show increased depth, and the log speed indicator remained fixed at fifteen knots as the steady throb of Cushing’s single propeller drove her mighty hull down and forward.
Keith’s mind flipped backward. In some ways this was so much like going to sea on a war patrol. But yet so different, and in the space of only fifteen years! In departing from Pearl Harbor, Eel had traveled almost entirely on the surface to her operating area. Except for daily drills and the ever present necessity to dive on appearance of a patrolling aircraft — all the more likely to be encountered as she approached enemy waters — she tried to stay on the surface in order to make more speed. The Cushing, by contrast, could make higher speed submerged. Furthermore, she could manufacture her own atmosphere from seawater, and dispose of unwanted gases, such as carbon dioxide and carbon monoxide, overboard. She was totally divorced from the surface, had no need for it, except for entering and leaving port. She could do everything she had to do submerged, far better than on the surface. She would dive as soon as she cleared the shallow water, and remain submerged until return. She would surface only if necessary.
Eel had been a much smaller ship than Cushing, but she had dived and surfaced more frequently, and her dives were more complicated to execute. There were diesel engines, up to four — five counting the dinky, or auxiliary charging engine — to shut off; for each, as it rolled to a stop, there were two exhaust valves — one hydraulic and one hand-operated — to be closed before the submarine went under (but not before the engine stopped revolving). And there were two big spring-loaded air inlet ducts to be closed in each engineroom with a great clang of metal.
Shutting the even bigger air intake valve, hydraulically operated, was one of the principal control room functions, to be accomplished after the engines had stopped and before the valve itself, located as high as possible under the after part of the bridge deck, went under. Then, as soon as the last hull opening was closed, usually the bridge hatch, there was always a great whistling and roaring as the control room bled high-pressure air into the submarine to confirm that she could hold air pressure and therefore was indeed watertight. A logical practice for a slow dive, right out of overhaul for instance, when some overlooked repair or some shore-based workman’s carelessness might have left an important hole unsealed. But in a fast dive the ship was half under before the last closure, the hatch or the induction valve, was shut, and there was no way to stop her downward momentum. If there were in fact a large hole, such as an open and unnoticed torpedo-loading hatch or a stuck-open air induction valve, the first sign of danger would be an increase in air pressure as the sea came in.
An artificial increase in air pressure during the act of diving would only delay detection of the first sign of danger, not help reveal it. But this had apparently not struck the submarine force authorities of that time. The whoosh of air, accompanied by pressure on the ears, had become part of the symphony of diving, welcomed uncritically by all because it signified orderly accomplishment of an orderly procedure.
In the Cushing things were much simpler. Air bleeding, with its attendant noise, had been abolished. Not only had the disadvantages been at last recognized, there were many fewer hull openings to close and hence less reason for a last-minute air test. There were no air-breathing diesel engines to shut off, no switching to electric motors for submerged propulsion, no haste to get down before an enemy aircraft could get on top of her with a bomb. In her engineroom a dive caused no change of any kind, except that the ship tilted very slightly downward for a short time and then leveled off again. To maintain the ordered speed, the engine throttleman might have to adjust steam flow to the turbine, that was all. If she went deep enough, he would have to close the throttle slightly, to match the reduced resistance to Cushing’s forward motion.
Something all submariners know: the laws of physics hold immutable, even though sometimes they seem to place effect before cause. A great deal of the power necessary to drive a ship through water is wasted in turbulence, visible in the form of wake astern and waves radiating outward from her passage. When a modern submarine is operating at shallow depth with any speed at all, there is nearly as much water disturbance as if she were actually on the surface, an incongruous and startling thing to any observer in the vicinity. But as the submarine depth increases, there comes a point when the pressure of the sea no longer allows turbulence to be formed. At this depth, and deeper, there is no surface evidence of her passage. The depth at which this occurs is dependent, of course, on speed; the faster the submarine is going, the greater her depth must be.