of the total elongation u03b4x the elastomers are generally capable of large elongation a designer may however desire to limit the extent of deflection for various reasons such as bond and seal fatigue in one embodiment the deflection of an individual elastomer seal 308 from the mean position is held to a 1 1 ratio of the elastomer seal span length l such that u03b4x 2 l in one embodiment the elastomer seal construction is similar in fashion to that of an elastomer annulus of a marine shock cell such as that illustrated previously in fig2 the elastomer seal comprises a vulcanized mixture of natural rubber the cylinders comprise sections of rolled carbon steel pipes the elastomer seal is bonded to the cylinders during the molding process consistent with techniques generally known to the marine shock cell industry several variations in the geometry and arrangement of the elastomer annulus may be desirable however to be adapted for use as an elastomer seal for a expandable cylinder referring now to fig4 a there is shown generalized reaction force versus deflection curves for a shock cell indicated by curve a as illustrated the reaction force increases with increasing deflection the slope of this curve a is the stiffness characteristic of the shock cell the area under the curve.