Abstract: A sensor for measuring movement of an object relative to a fluid has a housing fixed to a surface of the object and a spring on the housing formed by a plurality of blades each having an outer end fixed to the housing and an inner end connecting to a hub, with the plurality of blades defining a plane. Respective strain gauges are carried on the blades. A rigid pin is mounted on the hub of the spring, extends in a direction generally perpendicular to the plane, and projects from the surface of the object and into the fluid.