Christening a boat traditionally involves breaking a bottle over the bow of a new boat as the boat's name is announced. According to Heartland Boating, champagne is traditionally the liquid of choice, and women traditionally break the bottle.
Many superstitions have arisen through the years regarding the christening of boats. Because it is believed to be bad luck if the bottle doesn't break when it hits the ship's bow, many people in modern times use champagne bottles that have been pre-scored so they will break easily. Some people consider it even worse luck to launch a new boat or ship unchristened and point to the fact that the Titanic was never christened as proof.