I replaced it again today. For the last 4 years we had the "upgraded" dyneema line from BWyachts, and unfortunately it wasn't a good choice for the centerboard line. On my boat the line runs through cam cleats, and the cams just couldn't get a grip on the dyneema when it was wet. This led to the board dropping a few times under power, once putting us right over on our side.
I ended up tying a bowline in the end of it and looping it over a dock cleat installed on the genoa tracks, but even this would allow the line to drop about an inch, which means a fair amount of board was still down.
The new line is back to normal braided yacht line, and the cams seem to grip that just fine.
Inspection of the old line: as per my original discovery the main chafe happens at the turn down from the deck into the mast compression post. If you're concerned about your line, check that point first. Where the line goes through the centerboard itself was in better condition on both the original 18-year old line, and the replacement 4-year old dyneema line.
Red arrow shows the chafe point at the turn into the compression post (with centerboard up)
Replacement wasn't too hard. I used my car floor-jack to support and lift the front of the board back into place. Did the whole job myself in just over an hour while the boat was on the trailer, so not too bad.
