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.

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.

Abstract: The invention relates to a fin unit (2) with elastic attachment system on an underside (1) of a marine apparatus, such as a wind surf, kite surf, fly surf, wakeboard, knee board and particularly a surfboard. The fin in the mounting thereof is partially made to self-align in the flow of liquid medium with the aim of avoiding the hydrodynamic stall caused by the passage of high turbulence and/or large lateral movements caused by the surfer in extreme motion. The possibility for self-orientation is due to three fundamental parameters which are: the type of elasticity of the attachment system (3-4-5-27), the forward position of the centre of gravity G towards the leading edge (15) and the form of the root profile (9) of the fin (2) which has a thickening (7) of the trailing edge thereof.