47:55 That's the wrong side of the island, the "river" you were looking at is what we call the "New Danube" here in Vienna. It is in fact, as you noticed, not a river but rather an artificial lake with two locks or watergates on both ends separating it from the actual Danube river. The island you were standing on was build with the digging soil from the New Danube, this was built in order to avoid any flooding of the city when the Danube river was carrying more water than usual. :)
