Hi Ken, I have read with great interest your post and also the Article. Stemming from these I wondered if you would perhaps have any information at all on the general condtions under which merchant navy personnel were imprisoned on U boats.
In the case of a relative mine ( Capt. Joseph Crosthwaite) this was for a period of 80 or so days beginning in the Indian Ocean on 7th July 1943 and ending on 24th September 1943. Landed at Bordeaux and thence to POW camp Milag Nord, Bremen
His ship "Leana", owned by Williamsons of HongKong was attacked and sunk by U 198
( Kapitan Werner Hartmann).
I know little about the space inside a submarine, or indeed the workings, but it does not take much imagination to picture the cramped and uncomfortable situations under which the crew worked, especially on active duty. So where would a POW be berthed / guarded. Unfortunately first hand informationI never came my way about his 80 day sojourn but I understand that he was wearing a tropical white uniform (knee length trousers) when imprisoned and was stil wearing the same rigout on reaching Bremen. He was a very affable and pleasant individual but whether this would have in any way eased his experiences I know not. But I doubt that he would have been in manacles and hancuffed to a pipe!!!
I have not given up yet, but I was not able to find (perhaps it does not exist) any info about U 198s subsequent voyage from the Indian Ocean to Bordeaux but it is very likely I think that at some time she would have been involved in further attacks on shipping and / or avoidance of attacks on herself. A very frightening experience for a prisoner ....and the crew no doubt.

Best Regards, Pete.