Kim Nguyen was one of three men - including a man from Raleigh - who was on a powerboat that capsized near Cape Lookout more than a week ago.
His fiancé says the family will offer a reward of $10,000 or more if the boater's body is recovered.
Nguyen was supposed to get married on May 30. He was with his brother and friend, Jimmy Nguyen of Raleigh, when the boat capsized.
Kim Nguyen's brother was found clinging to the boat.