Several other things happen at about the same time, among them a sharp reduction in propeller noise, but most noticeable of all is a sudden increase in speed. The engines now have but one outlet for their horsepower: driving the submarine forward. She is no longer creating waves or turbulence. She has been freed from surface effect, which means there is now reduced resistance to her forward motion. And so she speeds up. To the throttleman in the engineroom, this is evidenced by an increase in propeller speed, and he automatically closes the throttle slightly, reduces the flow of steam to the turbines, holds the rpm to the ordered figure.
Another factor is propeller slippage. Defined as that percentage of propeller revolutions not converted into forward motion, slippage is essentially another measure of power wasted in turbulence. Designers have long known that the deeper a propeller can be, the less its slippage (another reason why the paddlewheel lost out). A deeply submerged submarine experiences virtually no slippage at all. Her propeller speed becomes precisely a measure of her speed through water. The distance she travels over any given time may be calculated with almost mathematical exactitude by multiplying the pitch of her propeller by the number of revolutions it has made, as shown on the revolution counter in the engineroom. For all these reasons, a deeply submerged (and properly streamlined) submarine can go faster than she can on the surface. This is true despite her larger displacement when submerged.
“Make your depth two hundred feet,” said Keith to Curt Taylor. It was an unnecessary order, but part of the ritual. Diving officers (and all planesmen as well) had already been instructed to keep the ship one hundred feet off the bottom, slowly increasing depth as the bottom fell away until ordered cruising depth, four hundred feet, was attained. The drumming noise of the surface had ceased. Air was no longer venting from the ballast tanks. Cushing’s speed stayed rock-steady at fifteen knots, her angle downward at a comfortable three degrees, her depth gauges slowly creeping upward toward the ordered depth. As they neared it, the planesmen without orders pulled back on their control columns, the ship leveled out, and Taylor turned to Keith.
“Two hundred feet, Captain,” he reported. “Fifteen knots, course one-two-five true. There’s a hundred and five feet of water under our keel. I have the dive and the watch, and will take over the conn as soon as Howie is ready to turn it over.”
“You’ve got it, Curt,” said Trumbull, who had been standing unnoticed in the background. “Course one-two-five true. Speed fifteen. Ordered depth two hundred feet, increasing to four hundred cruising depth. There is one ship in sight, well clear to port. No land in sight.”
“Aye, Howie.” To Keith, “I have the conn, Captain.”
It was all so businesslike, so controlled, so routine. There was very little of the thrill of the old-time dive, the split-second timing. Nor was there any need for a stopwatch in the hands of a quartermaster to monitor the time it took to get under.
Fast dives had been necessary in the old days, because a plane coming at two hundred miles an hour could bring disaster in a very short time. Eel had regularly submerged in less than thirty seconds. It had taken the much larger Cushing twice or three times that long, but diving from under aircraft attack was no longer the problem it used to be. In 1961, with a ship like the Cushing, cruising on the surface was for leaving and entering port.
With Cushing once more on even keel, Keith left the control room, walked thoughtfully forward to his own stateroom. He would keep Cushing on course one-two-five until clear of the hundred-fathom curve. Then he would change the ordered course to due east, and in about three days more, when clear of the Grand Banks, he would order it changed again, to northeast. Cushing would find her way by sound alone, probing constantly by fathometer and forward-beam sonar against the possibility of an uncharted bottom anomaly, or another ship. It was another ship which worried Keith the most. The ocean floor had been well enough charted of recent years to assure against sudden surprises standing on the deep seabed, but the possibility of another ship — a submarine — was a different matter. No U.S. or NATO submarine would be routed through the vicinity of Cushing’s plotted positions, but there was no telling what the submarine of another nation might do. Which was another way of saying that a Russian submarine, routed by its own navy department without relation to anything planned by that of the United States, might conceivably blunder into Cushing’s path. And if the other sub happened to be at the same depth — another remote chance in the huge world ocean — the collision could be catastrophic. But this was not something one worried much about. The mathematical chances against such an incident occurring were astronomical.
In the event of war, of course, it would be different, but even so the main danger of collision would be with submarines on one’s own side. Enemy convoys or task forces could be considered a magnet drawing all submarines in the vicinity. Even as far back as World War II, when diesel-driven submarines pursued enemy convoys on the surface and dived for attack after having attained a favorable position, the problem had been recognized. Coordinating operations so as to avoid the danger of collisions while submerged, or — even more to be dreaded — accidentally torpedoing a submarine on one’s own side as it also sought a favorable attack position, had occupied much thought and careful planning. Ultimately, if submarines continued to increase in number, there might come a time when the danger of collision would require measures similar to those controlling airplanes in the sky. But this time was far in the future. Keith gave it only a second thought, shrugged his shoulders, opened the letter from Peggy. As he read it, his forehead furrowed.
Darling,
I know this trip isn’t going to be as long as most of the trips you will probably be making on the Cushing and I know how busy you’ve been getting ready for it. So I didn’t want to bother you with this before you left, and would like you to think about it so that we can talk it over when you get back. I know it’s not supposed to be the code of the Navy wife to lay a problem on her husband just before he gets underway for a long cruise, but I’m sure it has happened before. The fact is, I wanted your last days in port to be as pleasant as possible, and I want to confide in you too. But I want to give you the whole story so that you can think about it, and then we need to have a long talk after you come home.
I love you very much, Keith, and when we are together everything is just swell. But you have been away for so many long absences. You couldn’t even be with me when Ruthie was born, because the Navy had you out on some sort of a long deployment or exercise or something. I’m afraid this is going to be the way our whole life together will be. We have never really been able to establish a home. We’ve bounced from one place to another. Even Ruthie, at age five, is beginning to notice something. “Where do we live, Mommy?” she said the other day, and I almost broke down because I couldn’t answer her.
I’m worried about the future, Keith. I know how much the Navy means to you, but remember, it’s really the only thing you have ever known. You got in it right at the start of the war when you were very young and have been in it ever since. But there is a lot more to living than just being in the Navy. This year you’ll reach twenty years’ service (why doesn’t the war count double? It should—) and become eligible to retire. This is what I want you to think about. We could move anywhere in the country, have our own little place, and live a normal life. You could easily get a good job, and with your retirement pension we’d never have to worry.