A spring member for marine vibrators. At least some illustrative embodiments are bow-shaped spring members including an outer surface, an inner surface; the outer and inner surfaces defining a thickness of the bow-shaped spring member. The bow-shaped spring member further includes first and second hinge members disposed on opposite ends of the bow-shaped spring member; a length defined between the first hinge member and the second hinge member; and a width defined along the first hinge member, the width in a range of from 50% to 150% of the length. The bow-shaped spring member also comprises a contour on the outer surface defined by a perpendicular section through the outer surface along the length, the contour including a medial portion having a curvature with a first algebraic sign; first and second peripheral portions abutting respective first and second hinge members, the first and second peripheral portions having a curvature with the first algebraic sign; and first and second intermediate portions disposed between respective first and second peripheral portions and the medial portion, the first and second intermediate portions having a curvature with a second algebraic sign opposite the first algebraic sign.