Type VII Interior Tour Series

[derstosstrupp]

Originally Posted by Onkel Neal

Ready lamps, 5 of the them, two rows: are they lit when it is safe to dive?

Correct, they are lit when ready/safe. In the case of the hull valve section, they light up when the electric sensors on the respective hull valve wheels detect that they are shut. In the case of the dive ready lamp section, they light up when the heads of the individual compartments flip the switch in those compartments that their compartment is ready for dive.

Originally Posted by Onkel Neal

Starting the diesels, they could start them with the e-motors, was that the normal method or was it more routine to start with air?

It was normal to use the e-motors to start when traveling in diesel-electric mode, which was used for much of the patrol. This is traveling on one diesel used for propulsion, that diesel turning its prop and also the motor on that side as a generator to generate power for the other side’s e-motor, which is turning the other side’s prop. Since they would have the other side’s motor running in this configuration anyway, to save on compressed air, they would simply start the other diesel with that E motor when they switched out the diesels every four hours or so in order to grind the exhaust valve seats.

Originally Posted by Onkel Neal

Oh, and you said there should be 3 hydraulic resevoirs next to the attack scope well,

is that 3 with a non-snorkel boar?
Or 3 with with snorkel or non-snorkel?

I thought the 3rd reservoir was for a snork-boat, the non-snork boats had 2, 1 for each scope...?

Based on what I have seen in early type VIIC design documents, it was always three. For instance here is part of a schematic from the Bootskunde für VIIC from 1940:



Same for the U-570 Skizzenbuch diagram for hydraulic system (earlier-war VIIC):

[Onkel Neal]

Originally Posted by derstosstrupp

when they switched out the diesels every four hours or so in order to grind the exhaust valve seats.

Wait, what? Grind the exhaust valve seats? That must have a very different meaning from grinding valve seats on an automotive engine... You must be referring to the exhaust valves in the line, not the heads, right?

[derstosstrupp]

Originally Posted by Onkel Neal

Wait, what? Grind the exhaust valve seats? That must have a very different meaning from grinding valve seats on an automotive engine... You must be referring to the exhaust valves in the line, not the heads, right?

There were flapper valve seats in the external and internal exhaust vents. Carbon would form on them and prevent a good seal when diving, and so periodically they needed to be ground. The external ones had pneumatic motors that would do it, but the internal ones you had to do by hand. You’d slap a big ratchet handle onto this male end here and crank back and forth for a while to unseat the carbon. Rinse and repeat on the other engine 4-6 hours later. Buchheim had the pleasure of doing this and describes it in Das Boot when he stands a diesel watch.



Some early boats were lost due to this design flaw.

[Onkel Neal]

Ok, that's what I thought. Not the exhaust head valves but the exhaust line isolation valves.

I thought, what? They pull the heads off those massive engines once every 4 hours to seat the valves? No, that's not happening.

[Dieselglock]

derstosstrupp


Thank you so much for doing these videos and the information you post on your Youtube site and targeting site.

[derstosstrupp]

Originally Posted by Dieselglock

derstosstrupp


Thank you so much for doing these videos and the information you post on your Youtube site and targeting site.

Thanks Dieselglock! Glad you are enjoying them!

[Nimmo55]

Hi Derstosstrupp, continuing to really enjoy these. Another 2 questions if I may:

1: Further to the issue of the colour of the deck; so black. Would that have just been a matt black colour designed to be weather resistant? I keep seeing photos of u boat decking and there is such a range of shades there to suggest the black faded pretty quickly to look almost grey. Trying to match a model colour.

2. Attack periscope optics: what we see in Wolfpack, is that realistic in terms of markings? Is that what a real u boat captain would have seen when he looked through a periscope?

Thanks in advance.

Apoll