Some mystery here
M1079 Düren was sold in 2001 and became SAS Kappa. But in this older picture, http://www.shipsnostalgia.com/gallery/showphoto.php/photo/364336/title/m1079-dueren/cat/524
the ship has two square windows but if you check a 2005 picture of Kappa, the windows are small and round http://www.shipspotting.com/gallery/photo.php?lid=2603993

Hi Gerolf,
following this thread:
http://www.saairforce.co.za/forum/viewtopic.php?f=3&t=1877&start=60
she has square bridge windows, so this then is SAS Kapa (ex-FGS Duren M1079)

Best regards, Frank

Hello Gerolf,

Six Type 351s Lindau-class minehunters were sold to the South African Navy in 2001. The remaining five ships were sold by the South African Navy to a private owner in 2009 for conversion into pleasure vessels.

Best regards, Frank

https://de.wikipedia.org/wiki/Lindau-Klasse

http://www.saairforce.co.za/forum/viewtopic.php?f=3&t=1877&start=60

It looks like a Lindau class minesweeper. Check this https://en.wikipedia.org/wiki/Lindau-class_minehunter
One of them, the Thübingen was transformed in a private yacht and kept a military aspect. Is that this one?

Hello Gerolf,
She looks like an ex German built patrol boat as shown on the link : http://www.generalequipment.info/47%20M%20CASTOR.htm
Scroll down.
Regards,
Yvon