You can run a line through a block on the buoy to the bow, the other end back to a pulley on the dock then to the stern. Both bow and stern fixed points. However you cannot leave the lines there permanently unless weighted and on the bottom. Otherwise you have to motor into the dock to make that attachment which gives you cleaner lines to handle. You need around 90' of line to allow the boat to swing. It also depends how much wind you have and what other boats are around. The boat may not move in a straight line.