A method of hydraulically activating a mechanically operated wellbore tool in a bottom hole assembly includes: holding moveable elements of the wellbore tool in an unactivated position using a shear pin; inserting one or more drop balls into a drilling fluid; and flowing the drilling fluid with the drop balls to a flow orifice located in or below the wellbore tool. The flow orifice is at least partially plugged with the drop balls to restrict fluid flow and correspondingly increases the hydraulic pressure of the drilling fluid. The hydraulic pressure is increased to a point beyond the rating of the shear pin, thereby causing the shear pin to shear and allowing the moveable elements of the tool to move to an activated position.