This Naiad fin is pressed onto its splined shaft, and stays put without fastenings. Removing it requires special equipment, though. Note the narrow winglet at the tip of the fin to make it more efficient.
When Regulator Marine decided to vault the 40-foot mark, they did it as only the North Carolina builder can: quad Yamaha outboards, an Armstrong bracket, and a hull ready for virtually any conditions. See the details here. ▶