A mooring Station for the Rhine River Boats for Fireworks Viewing or those special cruises where there is Beverage Service. Or possibly for Off Season Storage that is closer and the boats can be monitored instead of that round the way place out of easy observation.
"A mooring refers to any permanent structure to which a vessel may be secured. Examples include quays, wharfs, jetties, piers, anchor buoys, and mooring buoys. A ship is secured to a mooring to forestall free movement of the ship on the water." Credit goes to Wikipedia for the definiton