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Catfish 09-14-2016 07:08 AM

Someone knows the order of diving actions..
.. of a WW2 type VII boat?

1. under normal conditions
2. in a crash dive

What i'd like to know is what is done first, and if someone knows by whom of the crew..
Please let me know if i left something out, or correct me.

e.g. under normal conditions the captain wants the boat to dive to say 30 meters, "low and slow".
So captain or LI or the officer of the watch (?) would call out "Auf Tauchstation!" ~ "Man diving stations!", and the crew would act accordingly.

Hatch will be closed.

Diesels have to be stopped and uncoupled from the propshafts, the electric engines have to be coupled to the propshafts (or switched to electric engines from generator mode, if they were charging), and set to half or full ahead.

The Diesel air intake valves (head and foot ones) have to be closed, also the exhaust valves.

Dive planes fore and afte have to be set for diving, like "vorne unten x, hinten unten x" where x is the degree of angle.

With the command "Fluten!" ~ "Flood (the tanks)!" the main ballast tank upper valves have to be opened, to let the air escape and let water in from the foot valves. The lower valves were usually kept open, to improve the diving time.

The "Untertriebszellen" ~ "negative buoyancy tanks" would be already flooded, with lower valve open and upper valve closed. So they can be blown out right after the boat reaching 10-12 meters.

As soon as the boat reaches 10 meters the LI would order "Untertriebszellen ausblasen!" ~ "Blow negative buoyancy tanks!".

Then the fore and after dive planes would be adjusted to get the right diving angle of maybe 10-15 degrees, in a normal dive.

Short before reaching 30 meters the dive planes would be adjusted accordingly ("Vorne oben x, hinten oben x!") and the boat brought to level keel, while at the same time closing the main ballast tanks' upper valves to be able to blow them later, for ascending.
Trim tanks would be used to keep the boat straight and level, at said depth.

Then the boat would be trimmed for level cruising using the trim cells pumping water fore and/or aft, usually the bow a bit lower and the rear dive planes a bit 'up'. At least this is what Werner and others wrote, about crusing at depth.

Would this be the usual procedure for diving?

Thanks and greetings,

OT does someone have the eMail address of Paul, who we met at Laboe? I would like to order some of the magazines he showed to us, and maybe ask some technical questions. Have no fear, I will not spam him with mails or molest him ;)

sober 09-14-2016 05:25 PM

Watch Das Boot again .

Catfish 09-15-2016 03:47 AM

^ While "Das Boot" is one of the better representations, i would not take it as face value or evidence, e.g. thinking of the rivets giving in during an attack :) While some parts were riveted, the all-welded pressure hull was not.

Buchheim was "Kriegsberichterstatter", an "embedded" war reporter. And while he understood most things right, he was not a real learned U-Boat man, let alone what they did to his book in the film.

Aktungbby 09-15-2016 09:48 AM


The following tables were started from a description in the book Type VII U-boats, by Robert C. Stern, ISBN 1 86019 8554, 1998 edition. It is hoped to add to this description. 1. An electric bell gives the alarm. 2. The bridge watch prepares the bridge (close voice tube, demount portable machine guns, remove water-tight binoculars from UZO, remove radar detector aerial if necessary, etc.). 3. Simultaneously, vent valves for ballast tanks 5, 2/4, Quick diving tank (if empty) and 3 are opened in that order flooding from bow to stern to overcome the natural stern heaviness of the boat. If fuel is in ballast tanks 2 and 4, the main vent valve is opened with the inner vent valve remaining closed to equalize pressure in the ducts. 4. Simultaneously, the Petty Officer of the Watch goes below to his action station at the forward hydroplanes; the port quarter look-out follows to his action station in the conning tower with the Commanding Officer. The starboard quarter look-out goes below to the after hydroplanes. The Officer of the Watch is the last to go below. It is his duty to close the conning tower hatch. He then goes to his action station in the Control Room. 5. Simultaneously, close Supply and Exhaust air ventilation valves and any other openings in the pressure hull. 6. Planesmen position fore plane down and stern plane up. If it is a crash dive personnel not on watch might be ordered to move to the forward torpedo room to help get the bow under water. Initial angle of dive 4-7° to avoid propellers "racing". 7. Simultaneously, engine room personnel shut down and unclutch Diesel engines and shut the external air intake and exhaust valves. 8. Simultaneously, electric motor room personnel start electric motors 9. When the desired down angle is achieved (normally 12-15° but can go as high as 30 ° in a crash dive - at more than 40° acid may leak from battery cells) vent valve for ballast tank 1 is opened. 10. Simultaneously, the planes are brought to neutral position. Shut off Papenberg depth gauge at 18 meters and precision depth gauge passing 20 meters. 11. Quick diving tank is blown just short of empty to avoid releasing bubbles. This should result in the boat being at slightly positive buoyancy because the Regulating/Compensating tank is adjusted and maintained to achieve that. 12. Once tanks are flooded, the valves are shut 13. When desired depth is approached forward dive planes were moved up and stern down to level the boat at desired depth. 14. Boat is maintained at depth dynamically by use of the dive planes. 15. Because teh pressure hull is compressed with increasing depth the boat would grow heavier and the ballast pump or compressed air would be used to keep the boat at slightly positive buoyancy the opposite would occur if the boat moved to a shallower depth and water would be taken in.

Catfish 09-15-2016 10:56 AM

^ This is perfect, thanks Aktung :yeah: :salute:

Aktungbby 09-15-2016 11:36 AM

Of course nothing ever goes according to plan. Hans Goebler Iron Boats Steel Hearts :Dwas assigned to the zentrelle dive station manning the critical valves-tree behind the hatch ladder as he was competent. On one dive, as I recall, his arm got 'caught' and was unable to close a critical valve...threatening to plunge the boat below safe levels. Fortunately an alert officer turned the valve. I suffered similarly one time hanging my sleeve on a window handle simply exiting my eighteen wheeler nearly breaking my arm...plan 'A' oft goes awry. I have often wondered how many U-boats such as Endrass' and Prien's simply died in a dive accident under similar streß dive mishaps...It had to have happened.

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