I was tinkering with my newbie buddy's boat (and I sometimes have the same problem). He has a mainsail (new) that is obviously cut for a straight mast. His lowers are well back from the uppers, at the deck. It did help a great deal to make the lowers tight. That made most of the major distortion go away, but there are still wrinkles between the gooseneck and the spreaders - which can be made to disappear by pushing aft slightly on the mast half way down from the spreaders. No one seems to have anything rigged up to do that, so apparently it is only a problem for him and me. (?)
I do not think the problem is caused by excess back stay tension. The backstay had to be loosened more than the medium strength wind would allow (jib stay and topping lift tension needed), in order to make the mast be totally straight.
I also realize that distortion can be caused by the uppers being too loose, allowing sidebend, but in this case, like I said, the distortion was only down low - no distortion up high even without jumpers - and could be made good by pushing aft on the mast as stated.
Comments? Help?
Scott