This folk practice is breaking a bottle on the neck of a ship. This practice is a tradition performed whenever a ship was leaving on a voyage and sometimes was the first voyage that boat had made. Sailors and seamen are typically very superstitious because of the randomness of the ocean conditions. Therefore, many created small rituals such as this in order to create good luck and good weather for the upcoming trip. It was always performed before the ship launched and a bottle, typically champagne, was smashed across the foremost part of the boat.
The informant grew up on the East Coast in a sailing/nautical community. Because of this, he was constantly surrounded by much of the lore and traditions that accompany this culture. He did not learn it from any one person but was merely part of the set of customs. It was not done that frequently because it is typically done for a large trip but is still certainly part of the lore. They remember it because of their interest in sailing from an early age, meaning that the subject spent every day for parts of the year within that community.
I believe that this practice was probably old when technology wasn’t as sophisticated as today. Because of this, bad weather could spell disaster and there was sometimes little way to predict it. The conditions at sea were likely harsh and it was important to keep morale up, explaining the use of traditions and superstitions such as this.