CE Smith Trailer, 27600, 5′ Bunk Board Guide-On. Carpeted bunk boards provide proper center loading even in wind or side current conditions. Adjustable boat guides can be fine-tuned to work with your boat and your trailer. The pre-galvanized steel support posts mount horizontally on top of or below your trailer’s frame rail. Just slide the posts into the boat guide supports and secure the posts so that the distance between the bunks correctly matches the width of your boat. The bunk boards then tilt to conform to the boat’s hull. Guides will help to center your boat during loading and to hold the boat during transport. For larger trailer frames check out our Large Frame U-Bolt Kit (11416). Pre-galvanized steel parts are stamped from a sheet of steel after it has already been galvanized. The edges of the pre-galvanized parts often lose their zinc coating during the stamping process. Because of the thinness of the coating less than 1 mil and the fact that the edges remain exposed, pre-galvanized parts can begin to oxidize and rust quickly, so its recommended that they be primed and painted.