I'd appreciate some advice on dealing with a problem I have observed. It seems that a handful of the toe rail bolt holes on my '85 Hunter 25.5 have developed a circular dark discoloration that extends out from the bolt holes on the surface of the toe rails (about the diameter of a quarter). I have searched the archives but have only found a discussion on corrosion that is white and that has pitted the surface of the aluminum rail. Since my problem appears to not be this type of pitting but is a dark discoloration, I am not clear on what I am dealing with or what needs to be done to correct/restore the surface of the toe rails. Since the problem is only evident around some of the bolt holes, I am wondering if the stainless steel bolts might be interacting with the aluminum rail and causing the discoloration. If this is so, why is it only occuring around some of the of the holes and not all of them? By the way, the rails do not leak, and the boat has never been sailed in salt water. I would very much appreciate any advice on what to do to keep the problem from getting worse and also can the discoloration be removed? Thank you. s/v Elan '85 Hunter 25.5