The sixth of the seven Astute-class attack submarines (97 metres, 7,400 tonnes) has undertaken its first diving trials three weeks after being christened and commissioned by King Charles in September. These tests took place in the secure dock at BAE Systems in Barrow-in-Furness, some 60 kilometres north of Liverpool. They are the critical proof that the boat not only floats safely, but also does not capsize under water in practice and that everything works as calculated and planned. The basics of the method of "swinging" by shifting weight in the hull, which is still used by ship designers today, have a 300-year tradition - otherwise it's all done by AI.