Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Don.
I don`think any responsible navigator would use the term 90 degrees rudderangle. The order would be hard port or starboard the helmsman who would keep the steeringknob down till the rudder limitswitch stops the rudder at the preset max angle. If you want to turn on a nickel you used the propellers one full ahead the other full astern. A change in sailing course could be just a new compass figure and leave it to the experienced helmsman to come to that course using an appropriate rudder angle. In the event of an inexperienced helmsman you guide him by giving rudder angle orders which could be 5 degrees to port, when the boat start turning and approaching the new course the officer of watch order midships followed by steer so-so many degrees. As  said before in an emergency to avoid a collision or as in my time a drifting mine, you immediately gave the order directly to the helmsman hard port (or starboard) in those cases I believe fiddling with an order knob on the rudderangle indicator could be a dangerous delay and voicepipe would be used.
I cannot comment on the details of the rudderangle knob as I never saw same on any of our VIICs.
Tore

[SnakeDoc]

Hi Don,

The rudder order telegraph system seems to only indicate the angle setting for the rudders and not the desired course.  For instance - submerged and a rudder electrical failure due to a depth charge attack.  If the command is 90 degrees to port, the rudder order telegraph only goes to 40 degrees (port or stb) and the manual states that maximum deflection is 35 degrees manually and 33 degrees under electrical power.  The rudder angle will determine the turning circle at which the U-Boat turns to port.  I believe the forward speed is a factor in this equation as well.

The command "90 degrees to port" is related to the course directly. So if you are on the course 145 degrees, the helmsman changes the course to the 55 degrees. The rudder order telegraph was to be used only to pass the rudder deflection orders.
The course orders were to be passed verbally. So if you want to change the course from 145 degrees to "90 degrees to port" using the rudder telegraph only, you would have to set the value "30 degrees port" (for instance - it would depend how fast you want to get to the new course). The helmsman set the rudder to this value. Then, you (as the commander in the control room) are watching the gyro-compass and when the boat closes to the course 55 degrees, you gradually decrease the rudder deflection on the telegraph.

You have to remember, that helmsman at the emergency steering station had its own gyro-repeater (the unit from the control room), connected to the socket in the aft torpedo room (see the plan 16 in the Skizzenbuch you have received from Cuxhaven).

The rudder order telegraph system doesn't seem as useful as I initially thought it would be and I can see where the cost/benefit analysis scrapped the system.  Besides, how often did the U-Boat loose electrical rudder control.  I'm inclined to thing that if the U-Boat lost electrical rudder control, then the
phone to the helmsman in the Aft torpedo room would be the best line of communication.

Well, indeed it doesn't seem to be  very useful. However, I can imagine that it was designed to use in the combat, silent running conditions. The "U-Boat commander handbook" (http://archive.hnsa.org/doc/uboat/index.htm) says, that when being pursued by enemy, the silent running order was issued. Then the all unnecessary machines were switched off and the main rudder and diving planes were controlled manually. All the voice communication had to be reduced to minimum. In such situation (while doing evasion manoeuvres) the exact course steering was less important than the relative course changes. So passing the rudder orders by telegraph (not verbally) would make sense. But these are only my assumptions.

Q1.  Once they send a rudder order say 15 degrees to the helmsman in the aft torpedo room.  Do they then sent a zero degree setting?

They set the telegraph to zero degree. Generally, helmsman had to always make the rudder angle indicator pointer follows the rudder order telegraph pointer.

Q2.  I was thinking about the control room sending a 2nd command for another 15 degree rudder change.  How do they accomplish this change so the helmsman knows this is a 2nd command?

As long the first command was issued (set to telegraph), the main rudder was deflected by this angle. So second rudder change was senseless.

Q3.  This system just provides the rudder angle...  How does the helmsman get the actual course command from the commander?  By voice tube, by phone, or by crewmen repeating the command?

All three ways could be used. I would prefer repeating by crewman chain (as it would be most silent way).

--
Regards
Maciek

[tore]

VIIC Telephones.
Puzzled by the telegraph question and the rudder angle order system adviced by Maciek, I checked the excellent manual Uboatinformation for Type VIIC , year of construction 1939 effective July 15 1940   donated by Don translated by Maciek. In chapter V the various communications are described, both acoustic, electronic and visual. Internal communication by loadspeaker is mentioned, but as far as I can see not the telephone system. Further when looking at photos of older VIICs on the locations where you have the telephones on the later VIICs, you do not find the phones as on the image below where you see a photo of der Fuehrer on the place where you should expect to see a phone. As the phones were a very important communication link I believe they definitely should be mentioned under communication in the manual, I wonder if same was not installed on the early VIICs but introduced in the later execution  and as a consequence the rudder angle order knob was removed on the late VIICs. As far as I could check U 570 ( commisioned May15.th 1941) had the voicepowered telephones installed allthough of a different design and placed partly on other places than on U 995.
Tore

[Don Prince]

Hello Mr. Tore and Maciek,


Thank you for all this great info...  Mr. Tore what U-Boat is that in the photo where the phone was not there?  And one question off topic just for my personal info; was there ever a instance where an Escort Destroyer was on a depth charge run against a U-Boat, and a second U-Boat in a Wolf Pack took the Eccort Destroyer out by torpedo?


Regards,
Don_

[Don Prince]

Hello Mr. Tore and Maciek,


After reading Maciek's info about the Rudder Order Telegraph system and the use in the silent running mode; I was convinced that the system was indeed a handy thing to have on-board the U-Boat.  I made the photos smaller on page 196 of Skizzenbuch, so I could add the text info provided by Maciek.  (Thank you again Maciek for my education lesson for the day!).  I placed the latest version of Skizzenbuch in dropbox...


Regards,
Don_

[SnakeDoc]

Hi Gentlemen,

Puzzled by the telegraph question and the rudder angle order system adviced by Maciek, I checked the excellent manual Uboatinformation for Type VIIC , year of construction 1939 effective July 15 1940   donated by Don translated by Maciek. In chapter V the various communications are described, both acoustic, electronic and visual. Internal communication by loadspeaker is mentioned, but as far as I can see not the telephone system. Further when looking at photos of older VIICs on the locations where you have the telephones on the later VIICs, you do not find the phones as on the image below where you see a photo of der Fuehrer on the place where you should expect to see a phone. As the phones were a very important communication link I believe they definitely should be mentioned under communication in the manual, I wonder if same was not installed on the early VIICs but introduced in the later execution  and as a consequence the rudder angle order knob was removed on the late VIICs. As far as I could check U 570 ( commisioned May15.th 1941) had the voicepowered telephones installed allthough of a different design and placed partly on other places than on U 995.

I was also puzzled, when I had not found description of the voice-powered telephone in the type VIIC manual. I'm sure I have been reading about it somewhere...

Indeed, in the document effective on July 15 1940, the voice-powered telephone is not mentioned. The only electrical system for passing orders was the "Broadcast and announcement system" ("Lautschprecheanlage"). As described in the manual, it consisted of the central control unit (with the amplifier) in the radio room and speakers in every U-Boat compartment. To the control unit in the radio room there can be connected a record player or radio-receiver and the music from the record or radio could be broadcast through the boat. In the same way, the microphone could be connected and the announcement could also be passed through the boat.

But this system could also be used for communicating between the battle stations. For this reason, in several  places of the boat were installed terminals for connecting the headphones and the microphones. These terminals were in the aft torpedo room, E-motor room, control room, conning tower, officers room and forward torpedo room.
On the board of U995 the terminals are visible, but unfortunately without the headsets.

This system required to be powered for operation.

Some details on this system you can find in the section "II. General Announcing System" of the type IXC Design Study (http://uboatarchive.net/Design/DesignStudiesTypeIXC.htm).



(speaker in the control room of U570)

A Tore mentioned, the British report on U570 and his experience from KNM Kaura provide the information about second voice communication system (not present or mentioned in the 1940 manual) - the voice powered telephone.

Generally it consisted of several units located in the forward and aft torpedo room, control room and diesel engine room. In contrast to the broadcasting system, it did not require the power to operate. On the board of U995 you can see these units, but unfortunately, they are without the hand-sets. One note - the telephone unit in the forward torpedo room is not original (German war-time).

Some details on this system you can find in the section "III. Ship's Telephone Systems" of the type IXC Design Study (http://uboatarchive.net/Design/DesignStudiesTypeIXC.htm).

And one more thing - the report on U570 also mention about rudder order telegraph.


--
Regards
Maciek

[tore]

Maciek and Don.
I checked the voicepowered telephones a bit further. First of all a correction, on the photos taken by the US navy of U 570 the helmsmans place item B is marked as telephone. I don`t think this is correct, it is possibly an electrical coupling/ fusebox. The shutting handle could resemble a phone, see my image.
 I have, in my private collection, a photo of the lower part of the phone in the controlroom of KNM Kaura, taken 1954 and I believe this is the original phone. If you compare this to the phone of fwd torpedo room of U 505 provided by Maciek, I guess we can consider they are of the same type. U 505 a IXC, was commission in Aug. 1941and had the same phone as U 995 a VIIC/41. The phones on the museum U-995 is possibly not the original allthough they looks very much the same apart from the lower support for the microphone.
Tore

[tore]

Don.
I see I forgot to answere your question which boat substituted the telephone with Der Fuehrer. Sorry I don`t know which Uboat the photo refers to it was a common photo on the net.

Tore

[Don Prince]

Hello Mr.Tore and Maciek,


I'm going to add 2 more pages to Skizzenbuch to include all the info on the announcement system and the phone system.  Obviously the announcement system with speakers and head sets required an A/C motor generator, so this could not be used during silent running.  However the phone system looks to be DC powered and could be used during silent running.  Am I correct about the differences?


The phone receivers had the small crank and was it to get the attention of the receiver calling location?  I believe it was a buzzer OR a physical indicator (light or what)?  I'm not sure about which....


Regards,
Don_

[SnakeDoc]

Hi Don,

Obviously the announcement system with speakers and head sets required an A/C motor generator, so this could not be used during silent running.

The power requirements can be seen in the type IXC design study: the amplifier was powered by 220 V AC.

However the phone system looks to be DC powered and could be used during silent running.  Am I correct about the differences?

The phone system is not powered by any external power source. The voice converted into the electric signal was not amplified in any way, the signaling (getting receiver attention) was done by hand-driven small AC generator at each unit.

The phone receivers had the small crank and was it to get the attention of the receiver calling location?  I believe it was a buzzer OR a physical indicator (light or what)?

From the design study: the buzzer for audible signal and in parallel with buzzer the visual indicator. The hand crank driven magnetic type generator, which was used to power the buzzer and visual indicator at receiver side.

--
Regards
Maciek

[Don Prince]

Hello Mr. Tore and Maciek,


First, I would like to thank Maciek for the quick response to my questions about the phone receiver...  I uploaded the latest version of Skizzenbuch to dropbox.  I added pages 198 and 199 with the Broadcast and Announcement system, and the phone system.  Then I did the usual indexing and page number changes.  I believe Skizzenbuch is about completed for now.  Unless, of course, something else comes up where there is an information gap...


Regards,
Don_

[tore]

VIICs after WW2.
At the surrender 8. of May 1945 a total of 156 remainding U boats were scattered in various places, a substantial part of these were VIICs. The majorities of the uboats ended in Norway, a total of 96 consisting of various types. The three major allied countries kept some of  these boats mainly XXI for further investigation and were scrapped afterwards. The majority of the rest were destructed and sunk in operation Deadlight. However a few survived Deadlight and were in active service till early 1960. One VIIC in the French Navy and three in the Norwegian navy. One of the latter, KNM Kya ex. U-926 was modernized and got a "sail". Probably the only VIIC in this modern version. Below is an image showing KNM Kya in her old and new execution.
Tore

[SnakeDoc]

Hi Tore,


thank you for interesting information and pictures.
French type VIIC U-Boat Laubie (ex-U 766) was also modernized (after collision in 1950).




--
Regards
Maciek

[tore]

Maciek.
I was not aware of Laubies modernizing and thanks for the images. As far as I remember she was involved in collisions two times and the latest caused her to be scrapped. We had two of our submarineofficers sailing with her in the early 50- ties in order to exchange experiences in the VII Cs operation, but I don`t believe there was any cooperation in the modernising. As far as I can judge there is a big difference between the modern design of Kya and Laubie.
Tore

[Don Prince]

Hello Mr. Tore and Maciek,


The type VII U-Boats that had the modern bridge/sail in the 50's; did that make any improvement in the maximum submerged speed?  I would think the modern sail would present less forward resistance?


Regards,
Don_