Hi TailUK,
I have that issue of Marine Modelling, it's what inspired me to build this boat in the first place, however that build didn't include those items. I'm trying to build it more 'scale' than it was done, but I'll probably exclude those too if I can't figure out what they should be.
On the left of the second picture where I've marked the 'objects' is a stack of three lifeboats, I think they are inflated rubber dingies, and also often seen on the decks of S boats.
I think the German equivalent of the Carly Float was a square shaped floatation device made of balsa covered with canvas - you often see them in period photos attached to turrets on Kriegsmarine ships, but I'm not an expert! I haven't seen photos of any other devices in use.
One thought I had was that they might be sea mines covered in canvas - but it seems unlikely that a Luftwaffe ship would undertake any mining duties.
Regards
Hans