Ship launching ceremonies during Prohibition

What exactly did they smash across the bow of the ship when champagne was illegal? If it was champagne, was it obtained for the occasion by special permit, or was it donated from confiscated contraband? Or did they just use soda water or some such nonalcoholic substitute?

I thought I was in GQ.

Moderator, if you want to lock it go ahead and I’ll reopen it there. Or you can move it if you feel so inclined.

[Moderator Hat ON]

Moving to GQ.

[Moderator Hat OFF]

From US Coast Gaurd

“A ship is traditionally christened or given its name at the time it is launched into the water. When a ship is christened, it is tradition to break a bottle across the ship’s bow. This practice began in Britain in the late seventeenth century…
At the close of the nineteenth century champagne became the popular liquid with which to christen a ship. However, during prohibition ships were christened with water.”

A search on google turned up most uses being water.