Moss Hills and his wife Tracey have made a successful living as entertainers on cruises. They play guitar and sing – usually covering 60s and 70s hits – as guests dance until the early hours.One stormy night in 1991 they were working on the Greek cruise liner Oceanos off the South African coast when the lights went out, the PA system fell silent and the ship rolled so much that just staying upright was a challenge.Their actions in the face of extreme danger would affect almost all of the 581 people on board. Moss Hills tells Jane Garvey his life-changing story.