A series of in situ corrosion measurements on the wreck City of Launceston (1865) have confirmed that the vessel is close to collapse. If the long-term corrosion rate of 0.119[plus or minus]0.014 mm/year continues until 2005, the average hull plate thickness will have fallen to less than 1 mm of steel. In this condition it is unlikely that the vessel will be able to withstand the impact of the strong storms that periodically dominate the weather patterns in Port Phillip Bay. The local surface pH of the corroding metal was used to establish the most likely sites for disintegration of the hull. Corrosion data have provided evidence of the detrimental impact of weed clearing. -- SCMRE