Bunk Board Guide On Guide on your boat safely in high winds or strong currents. The marine grade carpet cradles your boat protecting it from scratches and dings. All hardware is hot dip galvanized for corrosion protection, and fits frames up to 4-1/4” in size. The bunk boards mount 21” above your trailer frame and have 13” of side movement on each side. Sold in pairs with all hardware included. Boards are 24" long.