This guy was even older than Don MacDonald, so you know he was salty........

He suggested that what I needed to do was run a 100' tape up the mast with the jib halyard and measure from the top of the mast to both of the chainplates for the upper shrouds. He predicted that what I would find is that the mast was not perfectly centered on the boat. I did, he was correct. We have not had the boat out under sail yet this season so I can't tell you if it makes a difference. However, the same old guy (not Don) told the person accross the dock from me the same thing last year. He measured, centered his mast and it did make a difference.