(great to see that you have a Wauquiez 43!┬* I love my ┬*little old Wauquiez Centurion 32)
Now to your receiver:
... is there any more info on company or type somewhere on the box? It doesn't have an own display?┬*
If you say that it is for the German Weather Service I assume that it works only on the fixed ferquency of 147,3 kHz ┬*that ┬*issues weather info for the North Sea
and the Baltic Sea
area, sent out as fax (RTTY) in a range of 200 to 300 nautical miles around Pinneberg (close to Hamburg). That might of minor value for you, assuming you ar sailing in french ┬*(Atlantic or Med)waters.
Or is it fixed to one or all of these frequencies: 4583 / 7646 / 10100,8 / 11039 / 14467,3 kHz? Their range is 200 to 1000 nautical miles - weather reports (fax) are issued in german and english, but as far as I know, besides the above mentioned areas of North-
and Baltic Sea
they only covers the Mediterranean
So, you might first check, if the provided german weather info is of any value for you, here
you find the schedules of the broadcasts with more info on what they cover.
Back to the receiver: If the receiver has an approval by the german "DEUTSCHE BUNDESPOST" it must be really old (for electronic gear) - out of the times when the telecom and mail┬* services were still united in the big DEUTSCHE BUNDESPOST. This state owned company was privatized in 1994 and divided into the DEUTSCHE TELECOM and the DEUTSCHE POST and with that the official type approvals for receiving and transmitting gear
(radios, radars etc) was issued elsewere.┬*
So, I assume that your receiver is from 1994 or earlier.
That makes it hard to find (downloadable) software in the net and should it be found, it might be hard to get this software running on our todays operating systems.... Most times those "black boxes" needed to be connected to decoders, because in those times it was not common that you connect the receiver do your computer┬*┬*