I have recently purchased a C-27 and decided to replace the thru hull fittings for the head sink drain etc. I believe the installed fittings are original. They are plastic with a with a hex nut head on the inside. Some of the fiberglass from manufacturing is left on top of the nut. There does not appear to be any exterior portion of the thru hull. What will happen when I put a wrench on the plastic hut head?
