Fibreglass reinforced polyester laminates covered with a gelcoat system are subject to blistering, when immersed in sea water. A mechanical model, based on the theory of plates, was applied to circular blisters in the first publication of this series. An experimental illustration of the model, involving gelcoated polyester laminate and ageing tests is reported here. Special interest is focused on the radial rate of blistering, the shape of the blisters, the calculation and the time dependence of the internal pressure and the associated stresses.