Tides Marine Zero Draft FRP Tubing is used primarily for building rudder tubes and shaft logs. Made from high-strength epoxy resin using a proprietary Tides process, its bore is dimensionally constant from end- to-end. Unless otherwise requested, standard wall thickness is 1/4". Stock inside diameters are 3" to 8 1/2" in 1/2" increments. To order, specify inside diameter and length needed.