Yes, there's also a forum where Werner Jähnig used to contribute before he died. I think it had "marine" in the web address. He was a student at one of these Seeberufsfachschulen and conducted some of his research on the forum. That's where I was when my PC crashed. I'll have it my browser history and will post it in a mo.
Edit:
Here's that link:
Marinearchiv
There may be more from him on there but I had only just started looking into it.
And...
here's a related, potentially very useful PDF that I also downloaded (German). Only the index but it may be possible to find the rest.
Obviously the
book by Jähnig mentioned by Wim would be a great asset too.
This is where I got to with the list:
Seeberufsfachschule Bischweiler
Seeberufsfachschule Elsfleth
Seeberufsfachschule Essen-Werden
Seeberufsfachschule Eudenbach
Seeberufsfachschule Görlitz
Seeberufsfachschule Hohensalza
Seeberufsfachschule Hohenschwangau
Seeberufsfachschule Kammer am Attersee
Seeberufsfachschule Lindau
Seeberufsfachschule Neuwied
Seeberufsfachschule Ried/Wolfgangsee
Seeberufsfachschule Ungarisch Hradisch
Seeberufsfachschule Wesermünde (Bremerhaven)
Seeberufsfachschule Wolgast
The wearing of the HJ armband is mentioned here:
Schwangau: Dorf der Konigsschlösser