this seems to be a tug which was used primarily years back when the Hamburg port was still old style, compared to today. The channels and fleets between the various berth,s in the port were quiete narrow to navigate. These tugs have the bollard where the towing lines are attached (pulling-point) rather to the center of the tug, very close to the back of the bridge. This made it for them to
turn easier from side to side but still pulling. This tug has the propeller aft (todays tugs often have the propulsion direct under them,.if not two which turn both 360 degrees, mostly also direct under them or about 1/3 back from aft.) this enables them to virtully push the pivot point of the tug instead of just pull it.
Otherwise you are correct,they do look strange to todays eyes.
On top, of course I consider any tug builded pre 70,s as stylish compared with the todays look like a bath-tub or even worse round table. Possibly also because I started sailing in the 70,s and therefore still attached to that time