U-Boat: U-977 Mystery

[Zulu]

Hello everybody!
I'd like to ask for some opinions and /or possible additional information U977's voyage to Argentina. The main mystery for me is how could they navigate blindly from Northern sea via Iceland passage into Atlantic for 66 days.
In order to start a research I decided to understand what periscope was broken on the boat.
Schäffer writes in his book the following:
A few days after we had sailed our main periscope collapsed. This was serious, as we now had no choice but to use the Snort, and with the Snort we had to travel blind.[...] True, we carried a reserve periscope, but that did not help us out as it was short type, designed only for use when we attacked at night or in the twilight. The glass was a special one and through it we could only see what lay directly on top of us
Based on this information I assumed that main periscope here means attack one, and U977 was left only with observation scope.
But reading "REPORT ON THE INTERROGATION OF PRISONERS FROM U-977 SURRENDERED AT MAR DEL PLATA, 17 AUGUST 1945." I found the following:
"On 7 May the observation periscope was damaged due to its being left up while diving."

So at this point the question is : what scope was broken?

[nigelweysom]

Hello Zulu welcome to the Forum i cant answer your questions but I'm sure there are those amongst us who can
Nigel

[jorgeY]

Hi Zulu,

I'm new here, but your thread interested me (I grew up in Mar del Plata). Perhaps I'm a too late, but from I could read about the incident (I have a copy of the book too, but a german edition) I think it was not the attack periscope that went broken.

I think, what Schaeffer means with main periscope should be the Luftzielsehrohr. You can see with it allaround, also up and down, and it is longer. And there is where de I WO is at attack, controlling the water surface and the air. And Schaeffer mention the problems, that he had with him, letting think, that it was intentionally that the I WO didn't take it down causing that it broke.

At least that's what I could understand about the story, but I think there must be here people more qualified, who could help you.

cheers