Is it not possible to accurately portray the German Type XXI?

ColonelSandersLite · 08-28-15, 12:47 AM

What torpx said. Snorkeling isn't about maximum speed, it's about not having to surface.

RoflCopter4 · 08-28-15, 01:40 AM

Ah. Fair enough. Would it be standard practice then to run the battery down with the electric motors, stick up a snorkel, recharge them, take it down, run the battery dead, etc etc? This seems like it would be a problem if you were near the end of a cycle with low battery and suddenly you had to dive. On that note, would the electric motors be propelling the craft even while the diesels were charging the batteries while submerged? Or would you just have the diesels doing both and the electric engines off for the duration of the snorkel?

This doesn't even have to be a theoretical question: what do modern diesel-electric submarines do?

Sorry if this is getting wildly off topic. I've never really understood how the snorkel was used.

ColonelSandersLite · 08-28-15, 02:57 AM

U-boats are direct drive, not diesel-electric. In their case, the electric motors are also the generators. They had systems of clutching the diesels and electrics. During economy cruise, one engine would be running in direct drive mode turning the screw, while the electricity generated by the electric motor in charge mode on the same shaft would be used to turn the opposing shaft. In charge mode, the diesel on one side would be running in direct drive mode providing some power, while the opposite engine would be disconnected from the screw and just turning the electric motor in charge mode.

Compare this to a US fleet boat where any one or more of 5 engines can be generating electricity and the screws are always turned by the electric motors.

I can't answer the question about historical SOP, though I very much doubt that it was general practice to run the battery all the way down. More likely they tended to recharge when battery charge was at some specific percent of capacity, or on a time table, or perhaps just tended to run with the snorkel up continuously if the strategic situation allowed.

08-28-15, 12:47 AM	#1
ColonelSandersLite Captain Join Date: Aug 2009 Posts: 481 Downloads: 74 Uploads: 3	What torpx said. Snorkeling isn't about maximum speed, it's about not having to surface. __________________ My SH4 LP

08-28-15, 02:57 AM	#3
ColonelSandersLite Captain Join Date: Aug 2009 Posts: 481 Downloads: 74 Uploads: 3	U-boats are direct drive, not diesel-electric. In their case, the electric motors are also the generators. They had systems of clutching the diesels and electrics. During economy cruise, one engine would be running in direct drive mode turning the screw, while the electricity generated by the electric motor in charge mode on the same shaft would be used to turn the opposing shaft. In charge mode, the diesel on one side would be running in direct drive mode providing some power, while the opposite engine would be disconnected from the screw and just turning the electric motor in charge mode. Compare this to a US fleet boat where any one or more of 5 engines can be generating electricity and the screws are always turned by the electric motors. I can't answer the question about historical SOP, though I very much doubt that it was general practice to run the battery all the way down. More likely they tended to recharge when battery charge was at some specific percent of capacity, or on a time table, or perhaps just tended to run with the snorkel up continuously if the strategic situation allowed. __________________ My SH4 LP Last edited by ColonelSandersLite; 08-28-15 at 03:13 AM.

08-28-15, 01:40 AM	#2
RoflCopter4 Seaman Join Date: Jun 2015 Posts: 42 Downloads: 51 Uploads: 0	Ah. Fair enough. Would it be standard practice then to run the battery down with the electric motors, stick up a snorkel, recharge them, take it down, run the battery dead, etc etc? This seems like it would be a problem if you were near the end of a cycle with low battery and suddenly you had to dive. On that note, would the electric motors be propelling the craft even while the diesels were charging the batteries while submerged? Or would you just have the diesels doing both and the electric engines off for the duration of the snorkel? This doesn't even have to be a theoretical question: what do modern diesel-electric submarines do? Sorry if this is getting wildly off topic. I've never really understood how the snorkel was used.