 A thick, tight mastic seal was introduced between the panels to prevent this issue from re-occurring.To save money during construction, stainless steel bolts were used to secure the external aluminium panels in place; however, this resulted in galvanic corrosion of the more reactive aluminium, so the bolts have been replaced by aluminium ones.Salts in water catalyse corrosion, a problem for the c2c fleet as they run beside the sea.