Jon Morley was on his way to Liverpool to visit friends in the city with his son and daughter when he died suddenly.
Brother-in-law Dave Herron said: "He was living in Dublin after spending many years in Liverpool and he was bringing his two children to visit friends in Liverpool on the Stena Line, and he was feeling a bit tired so he sort of decided to have a sleep.".
Dave said Jon's daughter, who is in her early teens, tried to wake her dad up when she discovered he had died in his sleep.