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.
Some onboard equipment is just indispensable, whether it’s required safety gear or those items on which you’ve come to rely help you feel safe. To see the things we won’t leave the docks without, look here. ▶