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?

http://www.youtube.com/watch?v=ISD1hJz53L8

Cheers

Jeff

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...

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.

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.

Agreed. Night surface attacks were conducted at low speeds, often using electric motors to keep noise and smoke down.

:yep: Even more in the book than in the movie the captain is far from perfect, and makes several mistakes.

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.

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...

Movies are just that - movies. They're not real life.

They're hinged at the front... the problem would rather be closing them... :hmmm:

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.

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

Could be. It also would help give the off-duty crew something to do besides sit and wait.

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.

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 :D.

.

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.

Fair enough. Thanks. :sunny:

Even with the modern plumbing, plumbs and trim tanks. The US subs crash dived in twice the time that the U-boats did ...:hmmm:. 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.

Hi Guys,

just a little detail in the scene: The captain orders "both engines slow ahead" just before opening the tubes. So he doesen´t go with the tubes open at flank speed.

From my point of view, it is not so unrealistic: The captain uses a moment where there are no escorts around and the moon is behind some clouds to reduce the distance to the target. So there is a good chance that nobody sees the speeding submarine. The attack itself is done at slow speed.

Greetings,
Stefan.

The U-Boats were little boats. Of course they were a bit more nimble than the larger American subs. The Type IX had comparable dive times and comparable size to the American submarines. When you're talking much less mass, you need less buoyancy to keep her up on the surface safely, which means less water to take on to get to neutral.

The crew is a much higher percentage of the weight of the submarine, so their positions within the boat influence the pitch angle much more than they would in a larger American boat. One thing you give up with larger size is nimbleness. But you gain the ability to take enough firepower to win a sub war. The Germans needed a lot more subs to have a chance. And they didn't have enough manpower to run the subs even if they had enough of them.

That was a major part of their problem getting the Type XXI to war. Nobody could run them on a war footing and they couldn't spare the crews from active duty to train them.

I tryied once in sh3, a convoy not reported, a manage to get parallel to them (1940 of course), at medium speed and lock on one of the outside targets to measure cousre and speed and plot it on the fly on the nav map. Use the compass for range, protactor for angle. I managed to get the speed and course right and at about at 3 or 4 filometres i turnded to about 20º off their perpendicular, once i had plotted the solution on the map and introduce it to the TDC. I launched a salvo and turned outside their path at my fastest speed. I was ready to be persuited for a while and then crash dive, but nobady seemed to care about me. I hit 2 targets, lucky shot. There was a gap in the escorts, not enough, you have to find the gaps and have luck.

Also, i was thinking as i am no expert, that tey did his is the one thing that breaks sh3, there is no wolfpack. I suppose that what they did was tryied this with 2 or 3 u boats in a night, and as most failed and were force to evade they dislocated the guard, and then it came the lucky one that got the convoy all mest up and with no escorts. I he was the one that sunk at pleasure, so maybe those heroes that got those big tonnages were just the ones that were at the right place at the right moment. And that just worked for a while, cause no yanki aint stupid...i suppossed. Also the u boats are the nown ones, but after learning about us sillent service, i think in overall they were far superior.

http://www.uboatarchive.net/KTBNotes...iveEdition.htm


Section VII :

(b) When attacked at Night. Night attacks on U-boats are in the nature of things generally made in the vicinity of convoys. Whether the U-boat is attempting to attack on the surface or has been detected submerged the tactics may well be to surface as soon as possible and escape at high speed.

(c) Asdics. Some of the limitations of the asdic are known to the enemy. It is realised that contact must necessarily be lost when running in to attack and sometimes as soon as the attacking vessel is committed U-boats increase to full speed and work their pumps if required. Many commanding officers endeavour to keep their boat bow or stern on to the attacking vessel in order to give the narrowest extent of target. The ping of transmission can be heard by hydrophones in a U-boat at greater range than that at which it is first possible to get an echo. When the A/S vessel is at close range the transmission can sometimes be heard aurally.

(d) U-boats sometimes deliberately allow themselves to be sighted while other boats in the vicinity get away or attack without interference.