Hi Guys,
I concur, I have assumed that they are 2cm barrel stowage tubes as they are the right dimensions, it could be a photo of the U 190 as she did have these tubes fitted, where as after the schnorkel was fitted to the U 889 she did not have them, see attached photos. Of course the problem is amplified by the fact that after every patrol the boats had a refit which could include weapons and fittings changes, so not only do you need to know if you are looking at the right boat but at the right time.
Regards
Jon