Gee, it kinda reminds me of the barriers used to catch airplane on a WWII Aircraft Carrier. You should only need one of those if you face strong winds or currents.
Of course, on all boats, if you can get one line on a cleat, you can use the engine to complete the docking. Say you pull up to the dock, and select neutral, and move to get a line on the bow. By this point the stern has drifted away from the dock.
Put the motor in reverse idle, turn the wheel right, and let it pull itself back to the dock.
Alternatively, if you get a line on the stern, put the motor in forward idle and the bow will move to the dock.