Looking for clarity on this section of "Run Silent, Run Deep"

[hunter301]

I am in the process of reading "Run Silent, Run Deep" and this section really had me scratching my head. Since it was written by Edward L. Beach I figure the technical aspects have to be right on but I can't figure this one out. The Ensign Blockman who was running the approach had the magnification set to low on the scope and determined a range to target of 2400 yards. But when the commander did a double check of the target he gets alarmed because the scope was on minimum magnification therefore in his mind the target was actually 1/4 the distance away. I don't see how that can be. If he had the magnification on lowest setting it should be reading the targets actual distance. If it was on high then it would appear to be closer than it was. Anyway here is what I was reading. See what you think. If I'm wrong than you can help me understand why:
(Excerpt from Run Silent, Run Deep)
"The periscope rose out of its well reached the top of its travel, and stopped. Standing bolt upright before it, the Approach Officer reached for the handles, folded them down in to operating position, then gingerly applied his eye to the guard.
"Bearing-Mark," he said.
The acting Assistant Approach Officer red it for him, then turned back to fiddling with the Is-Was.
The Approach Officer jiggled the periscope back and forth with little taps with the heel of his left hand, his right hand cranking the range crank back and forth. "Range-Mark," he finally said.
"Two-four-double-oh!" read the yes-man, breaking away from the Is-Was and searching the range dial with his finger.
The Approach Officer was named Blockman, and so far as I could tell the name suited him. Rivulets of sweat running down his face and into the open neck of his sodden uniform shirt, he put up the handles of the scope and turned away.
The yes-man fumbled for the pickle button hanging nearby on its wire, pressed it, started the periscope back into its well.
It had been up nearly a full minute.
Hansen and I exchanged glances. Nearly at the firing point, the supposed enemy hardly more than a mile way, the surface of the sea smooth and calm, -and the periscope up in full view for a minute! On the other side of the control room Jim winked as I looked at him.
"Angle on the bow is zero." The words cut across the compartment, perhaps from Blockman or his apparently equally stolid assistant. All three of them were now huddled with the Banjo operator in an oblivious group.
Even assuming a fairly large range error, there should be several minutes before he would be upon us. Fifteen knots equaled five hundred yards a minute. Divide that into the range for the time, -nearly five minutes. Nevertheless I had not made an observation myself for some while, and there was just enough of uncertainty in the air, something which did not quite fall easily into place as it should have, which impelled me to do so now.
"I'll take a look," I said. I gave the order to the yes-man: "Up periscope"
The scope whirred up. I stooped by force of habit, captured its handles as they came out of the well, folded them down-and as I did so a suddenly cold feeling gripped me in the middle of the belly. The right handle, the one governing the magnification power of the periscopes optical system, was in low power instead of high!
This meant that the range, instead of being twenty-four hundred yards at the last observation, had been roughly one fourth of that, six hundred yards. Some time had passed since, the Semmes was running right at us, and the range might have been inaccurate at that! I flipped the handle to high power, rose with my eye to the eye-piece. Lightning thoughts flooded into my brain.
"Jim!"
"Right here, Captain!" Jim's voice was close. He might have noticed the hand motion with which I discovered the position of the control handle, had in any event come over to the periscope in case I needed him.
Perhaps Blockman had for some reason turned the -handle to the low power position after his last observation, actually had accomplished the range-finding operation in high power after all. In this case everything was all right...
The periscope popped out of water, stopped its upward travel with a familiar jolt. And there it was. Catastrophe. I took it all in. Solid. My head nearly burst with the shock of it. Chill all over my body. Prickling sensation at the ends of my fingers. "Take her down!" I shouted. It was nearly a scream. "Take her down emergency! Series! Two thousand a side! Sound the collision alarm!" Hastily I flipped the handle to low power and back to high power again.
I was looking at the most fearsome sight any submarine commanding officer can ever be given to look at. In high power, equivalent to a six-power telescope, which is exactly what it is, all the periscope could show me was a huge gray-painted steel bow, oddly broad because seen from right ahead, not slender and lean as a destroyers bow commonly looks, but deadly. In the center stood the sharp stem to which the bow plates were riveted, the rivets stood out plainly, -and some distance to either side I could see the outlines of numbers, too foreshortened to read the "189" which I knew them to be."
__________________

[sharkbit]

My guess, and only a guess, is that the stadimeter was calibrated to take the range at high power. I would think most observations are taken at high power.

Make sure you read "Dust on the Sea" that continue a right where RSRD leaves off. Also read "Cold is the Sea" which takes place during the cold war and completes the trilogy.

[sharkbit]

That should be "Dust on the Sea".

[sharkbit]

Stupid tablet- Dust on the Sea

[Platapus]

Are you sure it ain't Dust on the Sea?

[Hinrich Schwab]

Originally Posted by hunter301

I am in the process of reading "Run Silent, Run Deep" and this section really had me scratching my head. Since it was written by Edward L. Beach I figure the technical aspects have to be right on but I can't figure this one out. The Ensign Blockman who was running the approach had the magnification set to low on the scope and determined a range to target of 2400 yards. But when the commander did a double check of the target he gets alarmed because the scope was on minimum magnification therefore in his mind the target was actually 1/4 the distance away. I don't see how that can be. If he had the magnification on lowest setting it should be reading the targets actual distance. If it was on high then it would appear to be closer than it was. Anyway here is what I was reading. See what you think. If I'm wrong than you can help me understand why:
(Excerpt from Run Silent, Run Deep)
"The periscope rose out of its well reached the top of its travel, and stopped. Standing bolt upright before it, the Approach Officer reached for the handles, folded them down in to operating position, then gingerly applied his eye to the guard.
"Bearing-Mark," he said.
The acting Assistant Approach Officer red it for him, then turned back to fiddling with the Is-Was.
The Approach Officer jiggled the periscope back and forth with little taps with the heel of his left hand, his right hand cranking the range crank back and forth. "Range-Mark," he finally said.
"Two-four-double-oh!" read the yes-man, breaking away from the Is-Was and searching the range dial with his finger.
The Approach Officer was named Blockman, and so far as I could tell the name suited him. Rivulets of sweat running down his face and into the open neck of his sodden uniform shirt, he put up the handles of the scope and turned away.
The yes-man fumbled for the pickle button hanging nearby on its wire, pressed it, started the periscope back into its well.
It had been up nearly a full minute.
Hansen and I exchanged glances. Nearly at the firing point, the supposed enemy hardly more than a mile way, the surface of the sea smooth and calm, -and the periscope up in full view for a minute! On the other side of the control room Jim winked as I looked at him.
"Angle on the bow is zero." The words cut across the compartment, perhaps from Blockman or his apparently equally stolid assistant. All three of them were now huddled with the Banjo operator in an oblivious group.
Even assuming a fairly large range error, there should be several minutes before he would be upon us. Fifteen knots equaled five hundred yards a minute. Divide that into the range for the time, -nearly five minutes. Nevertheless I had not made an observation myself for some while, and there was just enough of uncertainty in the air, something which did not quite fall easily into place as it should have, which impelled me to do so now.
"I'll take a look," I said. I gave the order to the yes-man: "Up periscope"
The scope whirred up. I stooped by force of habit, captured its handles as they came out of the well, folded them down-and as I did so a suddenly cold feeling gripped me in the middle of the belly. The right handle, the one governing the magnification power of the periscopes optical system, was in low power instead of high!
This meant that the range, instead of being twenty-four hundred yards at the last observation, had been roughly one fourth of that, six hundred yards. Some time had passed since, the Semmes was running right at us, and the range might have been inaccurate at that! I flipped the handle to high power, rose with my eye to the eye-piece. Lightning thoughts flooded into my brain.
"Jim!"
"Right here, Captain!" Jim's voice was close. He might have noticed the hand motion with which I discovered the position of the control handle, had in any event come over to the periscope in case I needed him.
Perhaps Blockman had for some reason turned the -handle to the low power position after his last observation, actually had accomplished the range-finding operation in high power after all. In this case everything was all right...
The periscope popped out of water, stopped its upward travel with a familiar jolt. And there it was. Catastrophe. I took it all in. Solid. My head nearly burst with the shock of it. Chill all over my body. Prickling sensation at the ends of my fingers. "Take her down!" I shouted. It was nearly a scream. "Take her down emergency! Series! Two thousand a side! Sound the collision alarm!" Hastily I flipped the handle to low power and back to high power again.
I was looking at the most fearsome sight any submarine commanding officer can ever be given to look at. In high power, equivalent to a six-power telescope, which is exactly what it is, all the periscope could show me was a huge gray-painted steel bow, oddly broad because seen from right ahead, not slender and lean as a destroyers bow commonly looks, but deadly. In the center stood the sharp stem to which the bow plates were riveted, the rivets stood out plainly, -and some distance to either side I could see the outlines of numbers, too foreshortened to read the "189" which I knew them to be."
__________________

The Ensigns botched the Stadia reading on the scope and misinterpreted the distance in the range finder. When the magnifications change, the Stadia lines have a different scale factor. However, this scale factor is not delineated in the scope on the wires in a clear manner. If you assume one scale, but the scope is set wrong, you WILL blow the distance calculations. That is exactly what happened. Considering that the Semmes is a Clemson Class destroyer and swings as wide as a barn door at full rudder, I can certainly see why the skipper did what he did when he realized that the Ensign put the boat in a position to lose the conning tower to the Semmes.

[hunter301]

Originally Posted by sharkbit

My guess, and only a guess, is that the stadimeter was calibrated to take the range at high power. I would think most observations are taken at high power.

That doesn't compute either. If low power put the target 4 times closer to the sub than high power would put it 4 times farther away.

Originally Posted by sharkbit

Make sure you read "Dust on the Sea" that continue a right where RSRD leaves off. Also read "Cold is the Sea" which takes place during the cold war and completes the trilogy.

Already have both sitting in my library waiting for me to finish RSRD.