of individual ships and in the overall size of the fleet. In the 1760s the Lower Wet Dock (by then known as the Great Basin) was deepened, the Great Stone Dock was rebuilt and a new dry dock (known today as No 4 dock) was built alongside it over a five-year period from 1767. During 1771-76 the former Upper Wet Dock was reconfigured to serve as a reservoir into which water from the dry docks could be drained by way of culverts (enabling ships to be dry docked much more speedily). From 1789 work was begun on replacing the old wooden South Dock with a modern stone dry dock (known today as No 1 dock, it currently accommodates the museum ship HMS M33). North of the reservoir a channel was dug leading to a new boat basin, beyond which several shipbuilding slips were constructed on reclaimed land at what became known as the North Corner of the dockyard. The rest of the reclaimed land was given over to storage space for timber with saw pits and seasoning sheds alongside, as shown in the dockyard model of 1774. The open ground between the Basin and the officers' terrace was likewise used to store timber. Several of Portsmouth Dockyard's most notable historic buildings date from this period, with several older wooden structures being replaced in brick on a larger scale. The three great storehouses (Nos 9, 10 & 11) were built between 1764 and 1785 on a wharf, alongside a deep canal (or camber) which allowed transport and merchant vessels to moor and load or unload goods; the camber was rebuilt in Portland stone between 1773 and 1785. On the other side of the camber, on newly reclaimed land, two more sizeable brick storehouses were built to serve as a sail loft and a rigging store; the reclaimed land was later named Watering Island after a fresh water supply was provided for ships mooring alongside. The Double Ropery, over 1,000 ft in length dates from the same period; it is, however, the sixth ropehouse (since 1665) to have stood on the site. Both its immediate predecessors were destroyed by fire (in 1760 and 1770) and the current building was itself gutted by fire in 1776 as the result of an arson attack. It is called a 'double' ropery because the spinning and laying stages take place in the same building (on different