Before revision: A reach is a segment of a stream, river, or arm of the sea, usually suggesting a straight, level, uninterrupted stretch.Macfarlane, Robert, "Landmarks", Hamish Hamilton Press, 2015Oxford English dictionary, reach, n., third meaning ("part of a river which can be looked upon at once between two bends") They are traditionally defined by the capabilities of sailing boats, as a stretch of a watercourse which, because it is straightish, can be sailed in one reach (that is, without tacking).
After revision: A "reach" is a segment of a stream, river, or arm of the sea, usually suggesting a straight, level, uninterrupted stretch.Macfarlane, Robert, "Landmarks", Hamish Hamilton Press, 2015Oxford English dictionary, reach, n., third meaning ("part of a river which can be looked upon at once between two bends") They are traditionally defined by the capabilities of sailing boats, as a stretch of a watercourse which, because it is straightish, can be sailed in one reach (that is, without tacking).