Abstract: A mounting assembly for a removable foil improves acceleration, maneuverability, and control of craft such as boats or rideable boards (surfboards, sailboards, and the like) and also reduces repetitive stress exerted on the hull by foil bending and torsion. An off-center ball-and-cup joint in the mounting allows the foil to yaw and roll within a limited range in response to changes in lateral fluid pressure. A resilient pad in the mounting then exerts a restoring force to return the foil to a neutral orientation as the lateral pressure equilibrates. An elastically deformable cushion on the base of the foil may contribute to the resilient adaptation while excluding ambient water from the mounting. Optionally, the entire assembly may be mounted in a translation cage that allows adjustment of the foil's longitudinal position. Variations on removable foils, and cushions for the bases of foils, have thickened trailing ends to reduce turbulence.