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Raiders of the Deep: U-boats of the Great War, 1914-18» Forums » General

Subject: Some infos about Torpedoes in WW1 rss

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Christian Pregler
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Hello everyone!

I found some info about the torpedoes and U-boats of ww1 and Beery thought I should share them here.

U5-U17 (despite U16) were able to fire the versions with bronze or steel pressure tanks of the C45/91 (a 45cm diameter Torpedo from the same year like the C35/91 (entirely made of bronze))out of both tubes. U19 - U41 were meant to fire the 45/91 norm. out of one tube and the C35/91 out of the other one, but it was necessary that a special tube element (sth. that reduced the diameter of the tube for usage of under caliber torps) had to be installed in the tube. (It seems to have been rather tricky so it had to be done at the torpedo workshop (Torpedowerkstätte; they also built the torpedo-tubes and torpedoes, altered the tubes of the existing U-boats for the elements or older torpedoes and they altered the old torpedoes for usage on the U-Boats).

As far as I have understood it, this means that only one type of torpedo could be placed in the tube while on a Patrol.
U5 till U18 had 45 cm diameter tubes and from U19 on there were 50cm tubes installed (from U19 on also the Diesel was in use).

At least the 35cm Torpedoes needed an adaptor in 50cm tubes. If the other ones (e.g. 50 to 45) also needed those is not known to me.

The C35/91 and the C45/91 have been allowed for U-warfare at the beginning of 1915. But the standard Torpedoes were the two 45cm Torpedoes C/03 and C/06 as well as the 50cm Torp G/6 A/V

The used Torpedo was also dependent of the length of the torpedo tubes. E.g. there were various versions of G/6 Torpedoes with different length

The G/6 AV had 600cm, the G/6 AV** 610cm and the G/6 AV* 612,1cm (the AV**and AV* were faster as they had higher pressurized air)
There were also special adaptions of the G/6 for the U-boat warfare called KI, KII (this was the standard G/6 AV) and KIII (of which the latter was designed for sinking Merchants. It had worse performance than the C/03 and 06 (it was thought the U-boats didn't need high performance torpedoes due to their ability to come near the target.

The 45cm Torpedoes seem to have been removed from frontline service at spring/summer 1918 and the remaining 45cm tubes have been altered to 50cm.

In 1918 even the G/7 (50cm torp with 7m length and thus better performance) was introduced for some U-boats. Especially the big boats in the reach of the BdU (Flotillas I-V) seem to have received some of them. But they were cumbersome in the boats and hard to handle.

Even in the First World War an electric torpedo was constructed but it was not ready till the end of the war (it was meant to come into frontline service in early 1919.

Some Information about U155:
The ex- Merchant-U-boat "Deutschland" should be changed to a U-Cruiser in the shortest possible time. Because of this it gained 4 front-tubes and 2 aft tubes which were situated between the outer hull and the pressure hull and consisted of wireframe cages. This was problematic as the torpedoes could be damaged by explosions or harsh sea. These seem to have been reloadable as one of the books says that the cargo bays of U155 were converted to additional space for the crew and ammo (shells and torpedoes). The rest of the boats which should become merchants earlier received the 2 front tubes they have in Raiders of the deep.
Edit 1: It seems there was space for additional Torpedoes but the wireframe cages were not reloadable while on sea. The KTB of U155 states that they had 6 Torpedoes and fired 5, so 1 was left wich means there were no reloads. After the first Patrol of u155 near the azores, it was again altered while in Refit like the other U-Cruisers of that class and got 2 internal T-Tubes which were reloadable. The wireframe cages were just made so it could be used as U-cruiser as fast as possible.

There were also Mines which could be dropped out of the torpedo tubes, the so called Teka-Mines = Torpedokaliber Minen. This means they had a Diameter of 50cm just like the G-Torpedoes.
There could be 3 Mines stored in one tube. The power of those mines was less than that of the normal sea mines.
Some of the U-cruisers seem to have gotten some of them.
The U-Cruisers of the Deutschland-Class mostly got 14 TK-Mines, but they were rather ineffective as they had less power and were keen to float away. Yet some ships fell victim to them.

Books I used for this:
- Eberhard Rössler; Die Torpedos der deutschen U-Boote
- Eberhard Rössler; Geschichte des deutschen U-Bootbaus
- Eberhard Rössler; Die deutschen U-Kreuzer und Transport-U-Boote

As far as I see that was most of what I wanted to write, I hope I managed to make an understandable comment and didn’t get anything confused. I also hope that I posted some interesting information.
As you can see there was a plethora of different Torpedoes (I am far from having posted them all). I have to say that the choice of torpedoes in Raiders of the deep is a very sensible one. Having more in would overcomplicate everything and it would be hard to simulate the different performance of each torpedo.
I wanted to thank Ian that he made such a great board game which led me to this interesting topic!
If somebody has additional information or corrections then feel free to post them here!

Best regards

Christian
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James Moore
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I have also read about the G/7 torpedoes being used in the late war period on U-boats. The G/7 was originally developed for battle cruisers and battleships, and was used at Jutland in 1916. The source I found did not give any exact dates or which boats used them though.
I have been thinking about making a small mod for using G/7s, but the lack of information has been a big stumbling block. If I can find out exactly when in 1918 they entered U-boat service, and on which classes of U-boats, then I can throw something together..

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Ian Cooper
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This is amazing info! Christian has done a great job in finding this stuff in the German sources, and I think this could form the basis of some very nice variants for those who want more details in terms of torpedoes and torpedo-tube mines.
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John C
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Thank you Christian!
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James Moore
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FYI here is another source for info on German WW1 torpedoes:

http://www.navweaps.com/Weapons/WTGER_PreWWII.php


The G/7 torps had a bigger warhead than the G/6s, and twice the range. They were over 3 feet longer than a G/6 though, and of course heavier. I'm thinking these were probably used only on the U-cruisers. I need more info before putting the mod out though..



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Christian Pregler
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What I have found about the G/7 was that they were introduced for U-Boat use somewhen in 1917.

In the BdU area (U-flottillas I-V) 90 G/7 AV (AV=heater) and 203 G/7**(The G/6** and G/6* seem to have been faster, they seem to have been meant to run 40kn so I guess for the G/7 it is sth. similar) have been fired from 01.02.1917 to 31.07.1918

In the area of the mediterranean the U-Boats fired the following numbers of G/7 Torpedoes:

02.1918 1
03.1918 2
05.1918 14
06.1918 6

The G/7 had 50cm
Length 7020mm
Weight 1365kg
Weigth of the charge: 195 kg (160 for the G/6)
Range at 27kn: 9300m
37kn: 4000m
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James Moore
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Very detailed info on the G/7; this should prove enough to make my mod with. The Navweaps site doesn't have nearly as much. It only lists one type of G/7. It also only lists two G/6 types, the G/6 and G/6D.
The G/6D is listed as only being used on surface ships. Time to sit down and hash out a G/7 mod..

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Christian Pregler
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Really great you make that mod, thank you!

Sadly I couldn't find anything about the U-Boats that fired them.

For the U-Cruiser I found that those of the Deutschland-Class (151-157) had a mixture of G/6 AV (U 151 had them first on their Patrol to the North american cost) and KIII (as there were not enough G/6 AV for them (at least at the beginning))

Those of Project 46 (U140) had only G/6 AV, 19 of them.

Sadly no Info about the use of the G/7, but as they were used in the mediterranean there must have been other U-Boats firing them. No Cruisers were used there.

Edit: About the G/6D, the heater of the D Torpedoes was run with petrol which led to high temperatures. Thus the whole thing had to be cooled with waterand as there was only limited space in the torp, salt water was used (at least on the first ones with this system. Sometime later a fresh water tank was installed) which caused some problems sometimes.
As far as I know the resulting hot air steam mixture was even more effective than the sole heated air.

The other torps with heater were heated with spirit that did not get that hot.

I also found some tables with the percentage of hits and misses with torpedoes (don't know if duds are listed under hits or not). If anyone is interested in them just tell me.
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James Moore
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More good info on the G/7, thanks! I think this pretty much answers whether U-cruisers ever used the G/7; apparently they did not. So no U151 or U139 class. The Flanders flotilla also is not listed as having used them. The UB II and UC II boats would have been too small in any case.
UB III's probably did not use them either, but there is no way to know this. That being said, I am going to go with Mittel-U's (until more info surfaces) as being the only boats eligible to get G/7's in their torpedo load outs.
It is also unlikely that there was a big enough supply of G/7's that any boat could get a full complement of them. So I'm thinking a maximum of one third of the loadout for Mittel-U's operating in western Europe after January 1917.
Since so few G/7's were used in the Med, that was likely a supply issue, so the load out will be only one or two G/7, and only in 1918. Hope to have this done over the weekend..



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Christian Pregler
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Will post some more detailed numbers on the used torpedoes later, first have to make a table of them as with the forum text programm it is a mess of numbers.

Edit: Does anybody know how to bring an excell sheet up on BGG?
If I post the numbers the normal way they get an undisentangable mess


But the Info I wanted to post. The percentage of G/7 fired.
BdU (Flottila I-V)from 01.02.1917 - 31.07.1918
G/7 AV 4,27%
G/7 ** 9,62%

Mediterranean 1918 (G/7**)
January 0%
February 1,96%
March 3,77%
May 37,84%
June 14,29%
July 0%
August 0%
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James Moore
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Interesting stats for the Med. The percentages fall completely away after June 1918. My supply problem theory is looking to be spot on. Either very few G/7's were shipped to the Med, or they simply weren't available at all, except to boats that were loaded in Germany and made the trip down.
Since finding out which it was is problematical at this late date,
I think it will be easiest to just allow a max of two G/7 per patrol for Mittel-U's operating in the Med from January to June 1918 only. Boats operating in the European theater will get a max of one-third of their load out..

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Christian Pregler
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Yeah I think you are right with this. Maybe they stopped delivery to Austrian ports so late in the war because they feared they would collapse and the enemys get their hands on the torps.

The numbers seem good. So the G/7 will feel like a reward.
Maybe make a dice roll to see if you get them and how many. E.g. for the med 5=1 of them 6=2 of them? Maybe with a modifier with your rank.


Some more infos:
U43 - U46 could not have a 6.1m longe Torp as reloads behind the tube (not enough space). Thus they had to have the normal G/6 with exactly 6m (KII and K III). Maybe here you can only have the G/7 if it is loaded directly in the tube at the beginning?

The Mine-Uboats (UE I and the UC Series)could only fire 6m and 6,1m long torpedoes (the tubes were too short for longer torpedoes).

Sadly I coulnd't find any Info on what Boats had long enough tubes...
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James Moore
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Yes, I think with the deteriorating Austrian situation, that could be why no more G/7 torpedoes were sent down to boats operating out of Pola or Cattaro (if they were ever sent at all). I've been giving the torpedo tube length issue a lot of thought as well.
If the tubes didn't need lengthening, but there was no available space for G/7 reloads, then my thought is that they could only have been loaded into the tubes prior to departing on patrol. That way, any class of Mittel-U could have used them (again if the tubes were long enough).
It's entirely possible that the shipyards lengthened the torpedo tubes in order to use the G/7, similar to having to put sleeves into the tubes in order to use 45 cm torpedoes earlier in the war. With over 300 of these torpedoes having been used in action, something obviously was done..



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