On 7th March 1980, the oil tanker Tanio, loaded with 26,000 tonnes of heavy fuel oil n°6, broke in two in a heavy storm at the end of the Channel. The fore part of the Tanio floated vertically before sinking off Batz Island. The rear part tilted and slowly drifted. It was later towed to the port of Le Havre. Six thousand tonnes of heavy fuel oil were spilt into the sea. Cedre joined the POLMAR-Sea (Préfecture Maritime for the Atlantic) and POLMAR-Land (Préfectures for Finistère and Côtes-du-Nord) command centres. It took part in implementing a slick drift prediction model, contributed to an emergency behaviour study on the fuel spilt and helped to set up response techniques and the pumping of the fuel oil from the wreck.