All sails shrink over time
This is a fact. The simple solution for a bolt rope which has shrunk is to stretch it back out with halyard tension. Think about what any main would look like if you dropped about 5-6" of halyard. I think a lot like the picture. If the bolt rope has shrunk then you might have to use a winch to tighten your halyard enough to stretch it out. You can see that the wrinkles are in the lower half of the sail so you would need to loosen everything in order to pull them out with the halyard. I do agree with Alan, though, that there could be other reasons for the luff wrinkles. But from the picture it kind of looks like the main is not fully hoisted - although given the angle it is hard to tell. One thing I don't agree with is that mast pre-bend has nothing to do with mainsail luff wrinkles, because it most definitely can. Crank on your backstay and you get a flattened mainsail with wrinkles in the lower third which can be removed with the cunningham - or not. The issue of mast bend is more exagerated or pronounced on boats with very bendable rigs. Want to see a real good example of this, look up some pictures of Star boats racing and you'll see it on every boat. I think it is highly unlikely, however, that this Catalina 36?? in the picture is experiencing mast bend issues.
