Why are ships christened with a bottle of champagne?

Blood was originally used as a sacrifice to the gods of the sea to allow for a smooth passage.

They moved onto wine that was first poured into a silver chalice, from which a sip was taken before spilling the wine over the ship and casting the chalice into the sea. To cut cost William the III of Britain, ordered the Royal Navy to break a bottle of liquor against the ship’s side instead.

Prince Regent set in place the custom of choosing a woman to perform the ceremony. The bottle was then to be held by the neck and thrown against the ship, however the rules had to change again after one particular bottle missed the ship and hit a spectator.

As for how the wine turned into champagne, champagne has always been associated with birth and celebration, while also having no religious association.