Where results were only available over periods of longer than a year an average value for each year during the period in question was calculated. As time progresses it can be seen that the corrosion rate falls and yearly rates measured after a number of years can be used as steady-state values in estimating long term loss in thickness. For example the least corrosive location in this series of tests was at Comar with a corrosion rate of about 4/~m/yr. An additional steel thickness of 1 mm per face would provide corrosion protection for about 250 years. At higher corrosion rates the corrosion protection afforded by the same additional steel thickness is proportionately reduced. For example for Seabegs fascia with an estimated corrosion rate of about 12/~m/yr an additional steel thickness of 1 mm per face would provide corrosion protection for about 80 years.