wheel nut
Kevin; I always remove the wheel on my OC400 when the boat is in a slip (my own or a guest slip) or on a mooring, but not at anchor. Under the white outer knob of the clamp is a brass nut. There is no special nut. The wheel hub was frozen onto the spindle and required a bit of force, but it did come off. Soak the inner hub with a penetrating oil overnight. If that doesn't do it, e-mail me and I'll tell you how I managed to get mine off the first time. Good luck.