You steer 45 degrees off the course you really want to make for so many minutes and then you steer 90 degrees from that for the same number of minutes back toward the course you really want to make—see, so—and that gives so many minutes to the good—see. That was one way.
"How many minutes?" asked the captain.
Doc had to stop and think that over. "Twice the square of the total minutes—no, no. Take twice the sum of the squares of the minutes on the two legs—and get the square root and then you have the hypothenuse of the two sides of the triangle; that is, you have the number of minutes' steaming you make good on your real course."
The old skipper knew nothing of square roots or hypothenuses or anything that looked like 'em, and he had always laid his course out by compass points.
"All right," said Doc, and after a while laid out the zigzag courses in compass points.
The old fellow did not quite like it, so all that day Doc alternated between his bad patient and the bridge to keep the skipper reassured about the zigzagging. Also he urged the crew to have a special watch out for U-boats.
That night Doc and the seasoned signal quartermaster stood alternate watches on the bridge. Doc would take a nap; the quartermaster would take a nap; between them they were figuring to keep a sort of official navy lookout. There were ship's crew men on the lookout too, but the reaction from the shelling had set in. Doc used to find them asleep in the bridge wings.
Just before dawn of the second morning Doc saw a shadow looming on their starboard bow. He had another look. It was another steamer—a big one. She was drawing nearer. "See that?" he called to the man at the wheel.
"See what?" sort of drowsed out the man at the wheel.
The trusty quartermaster from the 352 was getting a wink under the bridge-rail. Doc yelled to him, at the same time grabbing up the megaphone and roaring into the night air: "Where you-all going? Where the devil you-all going? Can't you-all see where you're going? Keep off—keep off."