Even worse with a plastic boat, the dam thing has to be re-sprayed every few years, at great expense. I bring the buoy up very tight under the stem in order to reduce its range of destruction; whilst incorporating a heavy snubber to lend some "give" in choppy conditions. This is 12mm rope (4ton disp boat), but backed up with a loosely attached chain run in a plastic sheath. There will still be conditions when the bow comes into contact with the buoy so I have protected it with a acrylic canvas cover which is held in position by four ropes, two at the bow and two further back. You must be sure that any shackle to the top of the buoy is protected, a road warning cone, cut to size, works well.