Many thanks to Davidships for providing us with this valuable information about this vessel.
Now, the demolition has started for a few days.
It was long story and, when I looked at this a couple of years ago could not pin down her original ID with complete certainty but my money is on Yd 6033 (IMO 6856437):

Project 8057
115gt, 28.67 x 6.53 x 3.30m
built c1956-7 VEB Schiffswerft Edgar André, Magdeburg
M 400bhp-294kW 1scr BKW

1998 Roger W Retting**, USA, renamed JOLLY and moved to Dordrecht
200x moved to Amsterdam (NLD flag, brand:10243 Z A 2002, EUR 025.10243)
200x 2 masts added to transform her in a sailing yacht (registered as yacht)
2005 moved to Oostende and then Nieuwpoort, Belgium, intended to sail to the USA, later plans changed to sail to India. Detained as unseaworthy.
25/12/2008 broke detention but developed engine trouble in the Dover Strait. Towed by Ramsgate lifeboat and moored in Ramsgate; again reported detained
22/3/2009 arrived at Barfleur, France, again with engine trouble
12/2009 towed to Caen
5/2011 Roger Retting died unexpectedly at Dingle, Ireland of a brain tumour; tug effectively abandoned
2013 still present in Bassin Hérouville at Caen, reported as likely to be scrapped

* definitely a Project 8057 tug built for USSR in GDR, but the Yd No and early IDs above (from Piet van Damme's "TugList") do not make sense, and source unknown. The suggested numbers "636" and "632" point to:
Yd 6032 - not found
Yd 6033 (IMO 6856437) 1956 completed as MB-6033 for Soviet fishing fleet, Klaipeda; 1975 renamed MB-6032; 1992 Lietuvos Valstybine Zvejybos Laivyno Imone (Lithuanian State Fishing Fleet "YURA"), Klaipeda, renamed 0632. YURA was wound up in 1995.
Yd 6036 (IMO 6856463) 1957 completed as TRIJGI for Estonian Shipping Co [Soviet fishing fleet?], Tallinn; 1992 AS 'Nautex', Tallinn, renamed TRIIGI; 1994 Estonian Ship Management Ltd 'ESMAN', Tallinn; 1997 Hoiupanga Liisingu AS /Hansa Liisingu Eesti AS [bank]; 1998 Baltic BASU (State Unitary Enterprise Baltic Basin Emergency-Rescue Management), St Petersburg/Kaliningrad, Russia as GERMES; 2005 Russian registry closed.

** name often given as "Rettig", but his own writings and Facebook pages have "Retting".