O'Krepki is from Hammond, La., and recently graduated from St. Thomas Aquinas High School, where he ran track and played soccer. He was with about 35 classmates on the ship, and WWL radio in New Orleans reported that his parents were chaperoning the trip.
His uncle, Rick O'Krepki, said the family had no details about what happened.
"We are awaiting more word," O'Krepki told The Daily Star newspaper. "Hopefully, the brave men and women of the U.S. Coast Guard will be successful in searching for Bruce."
He asked that the family's privacy be respected and for people to keep his nephew in their thoughts and prayers.
Family and friends gathered at a church in Hammond Monday to pray for his rescue.
A message left by The Associated Press at a number listed for Rick O'Krepki was not immediately returned.
A search plane, helicopter and Coast Guard cutter were sent out to search.
The ship had left New Orleans and was en route to Key West.
