We will be replacing all of our thru-hulls next haul out in the spring. We only have 5 under the water line and our boat is 12 years old. Since we had some bad galvanic corrosion on our keel and our strut we thought this would be a good replacement as it's impossible to see the condition of the metal on an installed thru-hull and that's the last thing on a boat we want to fail. I have a couple of questions: First, hunter used wood disks on the bildge side of our thru-hulls. I know this is pretty common on production and custom boats of all price ranges. But wood in the bildge has always bugged me. I want to use a water resistant material. Any ideas? I thought about the recycled wood/rubber fiber composites used on exterior decks (Trex is a common brand). We could band saw to 1/2" thick. 2) The bottom of the 33.5's are very flat. Is it really necessary to fair the bildge side of the disks (wood or other) to fit the very slight rounding or could we just torque the sea-cocks down to them and let them fit themselves to contour? 3) Regarding seacocks. I have seen marine UL listed seacocks in bronze that have plastic balls in valve ($40.00 on up depending on size) or ones with stainless and teflon seats that start around $75.00+. Anybody ever see a plastic ball valve fail in a seacock? Any other comments or recommendations would be greatly appreciated. We intend to get all the supplies we need prior to starting the job (like that ever works out, right?) so we can finish in a day. Thanks. Doug