A boatman sets off from one bank of a straight, uniform canal for a mark directly opposite the starting point. The speed of the water flowing in the canal is v everywhere. The boatman rows steadily at such a rate that, were there no current, the boat’s speed would also be v. He always sets the boat’s course in the direction of the mark, but the water carries him downstream. Fortunately, he never tires! How far downstream does the water carry the boat? What trajectory does it follow with respect to the bank?