Yesterday I was watching a mast get stepped at my marina. As the boat owner was checking his halyards by stripping them out, he said, "OH,OH, we have a problem here." He immediately began cursing the &*()@$%^ squirrel. He had chased one out of his mast as he propped it up to be stepped. It seems that the squirrel had "wintered over" inside the mast. It stripped the casing off of 4 halyards to make its nest and only left the core. This was about 40' into his mast of about 50'. He had to replace the four halyards with new line.Moral: If you unstep your mast or remove the boom, put something over the ends of the mast/boom to keep critters out. A boom always gets taken over by birds in the spring. Mine is the open-ended type, so I keep a handbrush stuffed in there all year long.