Abstract
In order to measure the release rate of anti-foulant from a ship's hull paint, paint specimens were mounted on a ship and their loss of thickness after sailing was measured. Specimens were prepared by coating conventional paints onto steel plates. The major anti-foulants were cuprous oxide and copper pyrithione. They were mounted on bilge keel of a training ship. After sailing, the specimens were collected periodically and the coating thickness measured. The average release rate, estimated from the thickness differences, varied from 11 to 40 μg/cm2/day. The release rate increased throughout the voyage when both average sailing speed and water temperature remained high. Observations of the cross section of a coating revealed formation of a skeleton layer near the surface where anti-fouling substances had leached out. Obtained release rates and the observed coating structures, are similar to those in laboratory tests which used rotating cylinders.
