I spent a huge amount of time trying to come up with some way to keep
a boat centered between two pilings as the tide went up or down even
for storm surges. Thought about all kinds of mechanisms that kept
constant tension on the lines while allowing it to lengthen and then
shorten. THEN, somebody else thought of something really simple, an
idea I admire. It is simply balls with holes thru them threaded onto
the line that goes around your pilings. They roll up and down the
piling as the water rises and falls. I cannot remember the product
name, does anybody know it? Has anybody used it?