A deck view of tug CASTOR seen here at Hansahafen, Hamburg, 26.12.2013

I don't know if she is waiting for preservation, demolition or just forgotten and rotting away. In any case she's in a poor state. The most recent photo I found here at Shipspotting.com dates back to September 2007. Don't know if she was still in service back then, but judging from the photo I found she seems to be roughly in the same position today as back in 2007...

Built by Jade Werft, Wilhelmshaven, Germany
Yard/Hull no. 62 (Built for URAG - Unterweser Reederei, Bremen, Germany)
Year of build: 1959

First name: Gröpelingen
At some point during her career renamed Castor

Gt: 105
L/B/D (m): 23,16 / 6,22 / 3,00