Hi, I’m new but I have a specific question about uniform. I’ve been doing some research into officer’s coats and have found pictures of about half a dozen different men wearing a black 6x3 button coat with a scalloped yoke as part of their uniform rather than the more common 8x4 grey one. There seemed to be too many instances of it being worn to be considered non-standard. After researching their service records, I noticed that they all seem to have joined the U-boat service before the start of the war. My questions are:

1) What was the deal with this black 6x3 coat? Was it the original regulation officer’s coat or was it a semi-official private purchase sort of thing before the uniform became standardised?

2) Roughly when did the grey coat get introduced?

3) Why was the black 6x3 coat discontinued?