Operation Sea-lion

My grandfather was a German cabinet maker who worked at the Rotterdam / Heijplaat (Hyplaat) harbour in Holland for a construction company based out of Essen. This company, among others, got contracts from the German army to prepare barges like this one for Operation See Loewe (Sea Lion). He took photos of the work in progress (although this was strictly forbidden). The film material was given to a friend to develop. My grandfather only saw his photos once in a German military magazine after the war. If anybody would know, I wonder what the source is for this photo and the other German photos? Could anyone help me or make any suggestions?

Hi @FelixS
It is difficult to say who the source was for this photo, I have done a reverse image search and cannot fond any references to it.
I did a Google search for 'Operation Sea Lion Barges
https://www.google.co.uk/search?q=o...KEwihm5SAzurMAhUILMAKHR8xCaAQ_AUIBigB#imgrc=_

An interesting story about you Grandfather, do you have any more information on his exploits?