In 1862, the dockyard was again re-modernised by engineer John Rennie the Younger. Most of the new work concentrated on St Mary's Island. Which had been recently purchased by the Admiralty for the new works. This included the three huge basins along the creek, linked by passageways. This shortened the time taken to reach the dockyard from Sheerness. A plan was also drawn-up for the bend of the river to be converted into a 50-boat basin. This was estimated to cost too much and was rejected. The spoil from the basins was spread acrost the island, filling the marshes.