“It’s important to do mad things. I don’t think it’s very wise not to do mad things.” So says Danny Sheehy, sagely. And what could be wiser than for a writer, an artist, a stonemason and two musicians to make a wooden-framed, canvas-covered boat and sail it, from Dublin, across a couple of seas, to join the route of the Camino de Santiago de Compostella? Sheehy is one of five wise men on the stage in the Ulster Museum, along with Glen Hansard, Brenden Begley, Brendan Ó Mhuircheartaigh and Liam Holden. Middle aged, weather beaten, grey haired, and with a…