Underwater Hull Cleaning by Laser - Feasibility and Perspectives

The underwater cleaning of ships faces regulatory, environmental, and economic issues. Mechanically abrasive cleaning methods, such as high-pressure water jets and brush cleaning, meet legal and ecological requirements only to a limited extent or under strict constraints. On the other hand, cleaning the underwater hull makes a valuable contribution to minimizing fouling. This in turn prevents the spreading of species and elevated greenhouse gas emissions. The research project “FoulLas” aims to overcome the existing limitations with a novel laser-based cleaning approach. At the Fraunhofer Test Center on the German offshore island of Helgoland, a test facility was set up for this purpose, which irradiates coating samples (commercial SPC, FRC and hard coatings) immersed and fouled under natural conditions, with an infrared- or a blue laser at adjustable intensities. The laser irradiation should neither damage the coating nor cause release of biocides and other substances into the surrounding water. The goal is to lethally damage the fouling organisms so that they detach from the hull at the latest when the ship is underway again. The present paper gives an overview of the current promising status of the project after 2.5 years of development and testing.