If your dead set on a floating dock I know some guys put a walkway on their docks that are on a big hinge. The walkway can then float up or down as far as you need it on the hinges. Depending how far up or down you will travel will be how long your walkway needs to be. If that makes sense.

RC

The only difference between a rut and a Grave is the depth. So get up get out of that rut and get moving!! Time to work!!