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Old 03-28-2012, 08:49 PM   #1
bratwurstdimsum
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Default Das Boot surface attack at flank speed - how?

Gentlemen,

I am sure this has been discussed before but I can't seem to find it on the forum: How in blazes does one charge at a convoy in the dark and plot a solution? The manual TDC tutorials I've read state that the boat must be stationary or nearly still to do this.

While we are on the subject, was the das boot depiction of the targetting and firing of the torpedoes accurate?



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Old 03-31-2012, 01:59 PM   #2
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Only in movies

I am no sub expert but I remember reading somewhere one can't (perhaps "shouldn't") even open the torpedo hatches while cruising at high speed - so if my unknown source is right, you simply cannot attack at flank speed under no circumstance.

BTW I too hope someone who has read uboat books can clarify this with solid references...
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Old 04-25-2012, 09:48 AM   #3
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A few remarks..

1- Charging in, surfaced, or merely decks awash in the presence of a destroyer is pretty unrealistic, unless it's darks enough, but the moon fading into the sky doesn't necessarily mean that the boat is in 'stealth' mode.

2- The captain was desperate and if you watched the full movie, they had a transmission of a convoy which they couldn't round to. capt. was supposed to make it steady into any of those conditions.

3- About the full speed firing, the torpedos had more speed than the boat even at low setting, and additionally get an air induction on their way out. So I don't see why not charge at full speed.

4- they moved to the forward room to quick dive. Imagine there were slots at the game for that.
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Old 04-25-2012, 10:26 AM   #4
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No, not much of Das Boot was accurate, at least in the operational sense. The interiors were great, but the crew's reactions were overstated and the portrayal of actual operations was limited and in some cases flat-out wrong.

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1- Charging in, surfaced, or merely decks awash in the presence of a destroyer is pretty unrealistic, unless it's darks enough, but the moon fading into the sky doesn't necessarily mean that the boat is in 'stealth' mode.
Agreed. Night surface attacks were conducted at low speeds, often using electric motors to keep noise and smoke down.

Quote:
2- The captain was desperate and if you watched the full movie, they had a transmission of a convoy which they couldn't round to. capt. was supposed to make it steady into any of those conditions.
Even more in the book than in the movie the captain is far from perfect, and makes several mistakes.

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3- About the full speed firing, the torpedos had more speed than the boat even at low setting, and additionally get an air induction on their way out. So I don't see why not charge at full speed.
Themrwho's question was whether the outer doors could open and that speed, not how fast the torpedoes were. I also wonder if the outer doors could open at 15+ knots.

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4- they moved to the forward room to quick dive. Imagine there were slots at the game for that.
That's something that's always bothered me. I've read that they really did that, but I wonder why, given that the diving tanks were capable of transferring up to 20 tons of water between fore and aft trim tanks, many times the weight of the entire crew.
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Old 04-25-2012, 10:32 AM   #5
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That's something that's always bothered me. I've read that they really did that, but I wonder why, given that the diving tanks were capable of transferring up to 20 tons of water between fore and aft trim tanks, many times the weight of the entire crew.
Every little helps, but maybe it was more psychological - if the crew get there fast they think they'll live, and if not...
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Old 04-25-2012, 10:49 AM   #6
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Movies are just that - movies. They're not real life.
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Old 04-25-2012, 04:55 PM   #7
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I also wonder if the outer doors could open at 15+ knots...
They're hinged at the front... the problem would rather be closing them...
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Old 04-25-2012, 07:17 PM   #8
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Quote:
Originally Posted by bratwurstdimsum View Post
How in blazes does one charge at a convoy in the dark and plot a solution?
Back to the sim guys, when I attempt it with the uzo it jumps all over the place making it impossible to do the mast hight calculations - do any of you have any simpler methods for manual tdc ? Anybody try it in the sim? I find a surface attack in the dark easier as I'm very rarely spotted even at flank speed unless I'm under 1000 yards.
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The convoy lights are dead ahead
The merchantmen lay in their bed
The thump of diesels hammers down
In the oily sea-the killing ground
His knuckles white his eyes alight
He slams the hatch on the deadly night
A cunning fox in the chickens lair
A hound of hell and the devil dont care

-Iron Maiden
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Old 04-25-2012, 08:35 PM   #9
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Quote:
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They're hinged at the front... the problem would rather be closing them...
I didn't mean the hull doors, but the front doors of the tubes themselves. They open outward, partly because they act as caps and can't go inward, and partly to make sure they seal under pressure.
http://www.maritime.org/fleetsub/tubes/chap3.htm
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Old 04-25-2012, 08:36 PM   #10
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Quote:
Originally Posted by Herr-Berbunch View Post
Every little helps, but maybe it was more psychological - if the crew get there fast they think they'll live, and if not...
Could be. It also would help give the off-duty crew something to do besides sit and wait.
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Old 04-25-2012, 08:41 PM   #11
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Quote:
Originally Posted by bratwurstdimsum View Post
Back to the sim guys, when I attempt it with the uzo it jumps all over the place making it impossible to do the mast hight calculations - do any of you have any simpler methods for manual tdc ? Anybody try it in the sim? I find a surface attack in the dark easier as I'm very rarely spotted even at flank speed unless I'm under 1000 yards.
It's very hard to do repeated calculations on the fly, so I would think that moving as slowly as possible is best. It's like one of my favorite misconceptions in surface wargaming. People want their battleships to be like Star Trek, doing evasive manuevers to throw off the other guy's shots while having your own still hit every time. Naval gunnery is far from precise, and you want your ship to the most stable platform possible, so you go as straight as possible. Evasive action is like smoke, useful only for running away when the chips are down.

You want your calculations to be as precise as possible, so you go slow and only turn when you absolutely have to.
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Old 04-25-2012, 08:51 PM   #12
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If you know target course and speed and you're close enough it is "doable". It all comes down to an estimation of "lead angle" for a zero torp gyro angle firing attempt and getting close as possible. Close range eliminates the effects of inaccuracies in target course and speed estimations. It is a calculated risk situation based on the time the escorts will effectively react on the sub's precence and the fact that a "safer" approach would probably lead to a "low odds" attack or even none at all.
Then you die .

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Old 04-28-2012, 03:41 PM   #13
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Quote:
Originally Posted by Sailor Steve View Post
That's something that's always bothered me. I've read that they really did that, but I wonder why, given that the diving tanks were capable of transferring up to 20 tons of water between fore and aft trim tanks, many times the weight of the entire crew.
Steve, the U-Boats did that because they were an older design than the US Submarines. American subs had fore and aft trim tanks to perform weight adjustments, U-Boats did not.

So they used the ballast they had--the crew. Their boats were smaller than the US boats and the crew forward trick did a great job of pitching the sub down for a quicker dive without all the plumbing and pumps the American boats had. Well, maybe it wasn't so great, but it was the best they had and they could dive mightily quick.
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Old 04-28-2012, 04:52 PM   #14
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Fair enough. Thanks.
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Old 06-24-2012, 01:25 PM   #15
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Even with the modern plumbing, plumbs and trim tanks. The US subs crash dived in twice the time that the U-boats did .... But im comparing VII against Gato/Balao. Maybe a fair comparision would be with the IX. but i dont know it s crash dive time.

Once the tanks were filled with water, they starting pitching down the sub, and it takes some time, the crew reaches the forward edge earlier than the water filled the tanks, and the planes got into position, so i think its an important help for the sub to sink faster. it s true that the crew weight is nothing compared to water s, but with the forward balance of weigth , it pitched down the sub and sinked, just like an airplane, with "inclined speed" more than heavier weight, later the tanks gets filled and the sub can gain depth without the use of speed.
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