 These tests were carried out the next year by "Dauphin" and when they spent a week and a half in the 72nd parallel north.During her last years, from 1980, "Requin" was fitted with the sonar system planned for the M4 refit of the SNLE.Similarly, "Dauphin" was extensively modified from 1986 to be used as a test bed for equipment and sensors to be installed on the s, then under design.