Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Simon.
The engine telegraph for KNM Kaura had Norwegian text and the encircled field Laden was substituted by Diving. Otherwise astern was on both dials inboard and ahead outboard, indeed on your photograph from the control room both telegraphs are marked MT port and stb. whereas on KNM Kaura only port and stb. so it is possibly not nicked from the U-995. The strange thing is when they changed the telegraphs on the museum U-995 they made a different marking, astern marking came outboard and thus ahead inboard. I wonder why they changed the telegraphs and the ahead and astern on the dials as it is obviously wrong.
Tore

[Don Prince]

Hello Mr. Tore,


Well, you got me involved so beware of dumb questions... There are telegraph units in the tower, in the control room, in the engine room, and in the e-room.


Q1. I don't recall seeing any on the bridge, so was the voice tubes used with a flashing light switch or a buzzer to get the engine room operator's attention?


Q2. 2 telegraph units in all places?


Q3. Did the tower and control room telegraph units send to both the engine room and the e-room telegraphs at the same time?  I see no reason to differentiate...


Q4. I believe the telegraph units were different (design and labels) for port vs starboard units?
Q5. Were there differences between tower vs control room labels?
Q6. Were there differences between engine room vs e-room labels?

Additional info: The three-position switches on the distributing boxes made possible selecting the active
orders transmitter (in the conning tower or in control room).


- position 1 - transmitter in the control room is active; transmitter in the conning tower repeats the transmitted orders


- position 2 - transmitter in the conning tower is active; transmitter in the control room repeats the transmitted orders


- position 3 - transmitter in the control room is active; transmitter in the conning tower disabled


There were additional switches on the control boxes, which made possible disabling acoustic signaling devices (bells and buzzers) in case of silent running.

kind regards,
Don_

[tore]

Don.
Q1. There are no telegraphs on the bridge. This was quite common on naval vessels at the time as they had an open bridge not only on the submarines. Orders were passed on via the tower hatch or voicepipe, depending on circumstances and weather, generally to the helmsman in the control room who operated the enginetelegraphs and normally did not pass on orders to the engineroom by voicepipes. Every time the enginetelegraph was operated, it activated both an acoustic alarm and a flashing red light in the engine room and E-room.

Q2. Every telegraph position had a separate telegraph for each shaft.

Q3. As far as I recall yes.

Q.4 The telegraphs were identical in design however as many components on a twin engine installation, in the engine room and controlroom port was a mirror execution of starboard as f.i. the astern markings were in both inboards. In the E-room I guess it was different, the starboard dial had astern on the right ( the port opposite) side thus towards aft at the switchboard maneuvering place, hence my assumption the Euro 2.999,- telegraph is possibly from the E-room.

Q.5. I don`t recall any difference.

Q.6. Same.

One final mark though, if you look at the photo of the engine telegraphs at the helmsman place in the KNM Kaura`s controlroom, you shall see a removable nameplate stating "Diesel" hanging on the nob of the port engine telegraph which means the order from the bridge is to run on diesel. On the substitute enginetelegraphs of the museum U-995 not only the dial rimring is different but there are no maneuvering knob as well.
Tore

[Don Prince]

Hello Mr. Tore,


on Q1 -  I was thinking about a night surface attack where the helmsman was on the bridge controlling the rudder.  I guess they would use the voice tube to change speed.  However, the diesel engine room is noisy and in order to listen for the commands, I believe there had to be a signaling device; like a switch on the bridge to cause the lights in the engine room to flash to signal the diesel operator to check the voice tube for speed commands...


Regards,
Don_

[SnakeDoc]

Hi Don,

on Q1 -  I was thinking about a night surface attack where the helmsman was on the bridge controlling the rudder.  I guess they would use the voice tube to change speed.  However, the diesel engine room is noisy and in order to listen for the commands, I believe there had to be a signaling device; like a switch on the bridge to cause the lights in the engine room to flash to signal the diesel operator to check the voice tube for speed commands...

helmsman took the station at the bridge only when manoeuvring in harbour. During the night surface attack, his station was in the conning tower, and he received orders verbally through the open conning tower hatch. If he was on the bridge, it would be impractical: first - there was additional person on the crowded bridge, second - during the alarm dive, there had to be steering panel detached, moved with the cable to the conning tower, there attached again. It would take too long.

So the commanding officer passed the orders related with the speed and course verbally (through the hatch or voice tube) to the helmsman in the conning tower, and he set the issued order at the machine telegraph and change the course according to the order.

--
Regards
Maciek

[tore]

Don-
Maciek put it right. In order to make the system of passing orders by voicepipes easy to understand I made the voicepipe sketch below.  It is only one voicepipe connection to the bridge. When you was cruising on surface in bad weather the top hatch was shut as the bridge was washed over by the sea which otherwise would flush down in the conningtower and controlroom . You reduced the people on the bridge to only officer of watch and an outlook. Communication was then via one voicepipe either to the conning tower and/or the control room (three locations). In the conningtower  the voicepipe orders could be passed on by separate voicepipes, (violet) to the controlroom, radio room and sonar room, the green to the CO., the yellow to control room and forward torpedoroom, blue to control room and aft torpedoroom. It is obvious that you could communicate to the same places from the controlroom as the conningtower, however in addition there was a voicepipes connection  pink to the aft torpedo room.
It might be of interrest to include the voicepipes in your Skizzenbuch as it clearly shows the system of ordercommunications
Tore

[tore]

Don.
Your question referring to night attacks made me remembering a scene of the outstanding movie Das Boot. If you remember after the sinking of a tanker you have spectacular view of the burning tanker observed by not less than eighth people on the bridge. As far as I remember the movie should reflect on a situation in October 1941. The Royal Navy did a lot of efforts to develop counter attacks of the wolfpack tactics in the early forties. A very important element was the development of a naval 10 cm. radar for observing surfaced submarines. I guess a first test was made as early as 1938. The equipment got a priority for use on the convoy escort vessels and the first usable sets were installed on two corvettes April/May 1941. The other corvettes followed soon. I have my shelf served on one of these corvettes in 1948/49 with this radar which compared to to days standard was not great but usable within a range of 7000 meters. I don`t know how much the German submarine CO`s knew about this radar in October1941 but to me it seems like an incredible risk to observe this tanker surfaced with a crowded bridge of at least 8 people. I wonder where the Uboat tactic movie consultants have been.
Tore

[SnakeDoc]

Hi Gentlemen,

I would guess, that during the night attack, the following persons would be at the bridge:
4 lookouts, commanding officer and torpedo officer - that would be 6 persons.

Regarding to the German awareness of allied radar in October 1941, here is some document:
http://www.ibiblio.org/hyperwar/USN/rep/ASW-51/ASW-14.html
where in the paragraph 14.2.1 is stated that:

From the start of World War II, the Germans were fully aware of the possibilities of meter ASV radar and had developed their own airborne search equipment, but it was not until the summer of 1942 that they concluded that the Allies were using radar for U-boat search and initiated a hurried program for the development of search receivers to detect the radiations. The first equipment to be installed on U-boats was the R-600 or Metox with a low wavelength limit of 130 cm. It was of the heterodyne type, thought to be the only type capable of sufficient sensitivity, and so it radiated energy, a property which eventually caused its abandonment. Nevertheless, it was used with apparent success, and the conditions of its introduction and use are of considerable interest.

--
Regards
Maciek

[SnakeDoc]

Discussing about machine order telegraphs, I would like to mention one thing.
The type VIIC U-Boat manual (http://uboatarchive.net/Manual/Manual.htm) on page 181 describes the following item:
"Rudder order telegraph and rudder angle indicator system"

This piece of equipment is related with the emergency (hand) steering in case of main rudder electric control failure. In such situation, the helmsman took his station in the aft torpedo room, near the air compressors, at the emergency steering station. There was located the hand wheel for driving the main rudder. The helmsman took with him the detachable gyro-compass repeater, to know the current course.
As we know, the helmsman received two kinds of orders: heading order (i.e. "on course 71 deg" or "on east course") and rudder order (i.e. "hard port" or "15 degree starboard") related with the rudder angle. If the helmsman was in the aft torpedo room, the heading order was passed to him verbally. But rudder orders could be passed by means of the "Rudder order telegraph" which was coupled with the "Ruder angle indicator system".

The rudder order telegraph system consisted of (as described on page 181 of the manual) from the rudder angle indicator coupled with the rudder order transmitter located in the control room and from the rudder angle indicator coupled with the rudder order receiver located in the aft torpedo room.

Unfortunately, I have never seen any photo related with the type VIIC U-Boat, showing such system. Similarly, it can not be found on board of U995. I guess, that the simple rudder angle indicators (without rudder order transmitters and receivers) were installed due to cost/labour saving purposes.

However, such device can be observed on the board of U505. I have attached the photo "U505 main rudder order telegraph.jpg", which shows the rudder angle indicator with the rudder order transmitter. You can see two pointers (one above the other) - one showing the current rudder deflection, the second is the rudder order. Below, you can see the knob for setting the rudder order. The label at the bottom of the dial says: "Hauptrudder Telegrf Geber Lagenzeiger" that means "Main rudder order telegraph transmitter and indicator".

At the emergency steering station (in the aft torpedo room) was installed the similar unit, but without the knob.

--
Regards
Maciek

[Don Prince]

Hello Mr. Tore and Maciek,


I just could not let all the good info pass without updating Skizzenbuch.  I changed pages 186, 196, and 284.  I uploaded the latest version of Skizzenbuch to dropbox.  Please let me know if you approve...


Kind regards,
Don_

[tore]

Don.
I have no remarks. I cannot recall ever seen the rudder angle telegraph on any of our VIICs all commissioned after Sept. 1943. Contrary to the navigation order: steer or come to so many degrees, the rudderangle order was usually given during normal maneuvering and emergencies. Turning a small nob at the rudderangle dial seems to me to be a bit bothersome as the order was usually given verbally by the officer on watch directly to the helmsman requiring a quick action. As far as I recall we tested the emergency aft rudderoperation by using the telephone or the voicepipe port side aft of starboard main switchboard next to the emergency rudder helmsman.
Tore

[SnakeDoc]

Hi Gentlemen,

I would like note one more thing, related with the rudder order telegraph/indicator.
If you look closer at this unit, you will see the label "Stromlos" at the
left edge of the dial. It is the "power failure (Stromlos) annunciator flag". When
the telegraph/indicator subsystem is powered, this flag is held by the electro-magnet
at the edge of the dial. When the power is off, the electro-magnet releases the flag,
which falls under its own weight to the dial centre. This simple system signalled the
operators, that the power is off, and the pointers are not necessary indicating the
desired values.

--
Regards
Maciek

[tore]

Don and Maciek.
In addition to the powerfailure remark from Maciek it is perhaps worth while to mention if the electric rudder angle indicator fails it is like on the hydroplanes, a mechanical ( teleflex) angle indicator at the emergency steeringcolumn as can be seen on the image below. The electrical rudderindicator is on the top aft of port main switchboard.
Tore

[Don Prince]

Hello Mr. Tore and Maciek,


I have many questions...


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 commander gives the order for 90 degrees to port, but it looks like the helmsman would need to be trained to know what angle to set the rudders depending upon the forward speed to achieve the port 90 degree course with the greatest distance from the spot of the command.  Otherwise, if the command was "90 degrees hard to port", then the helmsman would know to apply full rudder angle.  Am I off on a tangent again?


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.


Now for a few questions about the rudder order telegraph system...


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? 


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?


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?


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


I updated Skizzenbuch and used your photo of the Aft helmsman's station with the telephone (I like that info!)...


updated pages 183, and 196.


Regards,
Don_