there a few different ways to combat the tide. Most criss cross the lines at the transom and leave enough slack to allow the boat to move side to side without hitting the dock and up and down with the tide. And along the same for the spring lines. I have seen some cool tide rings like n the pic below...they roll up and down the pileing when the tide changes. And some marinas have tideslides mounted to the pileings that move up and down with the tides..