The 1719 Establishment was the first formal 'Establishment' (mandatory requirements to govern the construction of warships for the Royal Navy) laid down to govern the construction of all ships built or rebuilt down to those of 20 carriage guns, whether in the Royal Dockyards or by commercial contractors. It did not apply to ships and other vessels with fewer than 20 carriage guns (which were unrated vessels). It superseded the previous 1706 Establishment, which had only specified the major dimensions of ships of 40 guns and above (and had specifically excluded the 100-gun first rates).
The new 1719 Establishment was applied to all new ships from first rates down to sixth rates inclusive (i.e. all ships of 20 or more guns) as well as to rebuilds of existing ships. In fact, for the first 20 years from 1719, all ships were technically rebuilds of existing ships, as the Admiralty were constrained not to build "new" (i.e. additional) ships. During this period, a rebuild could amount to anything from stripping off planking to facilitate replacement of rotten timbers and adjustments to suit the required dimensions, or complete dismantlement and construction of what was, for all intents and purposes, a completely new ship making but the scantiest use of timber from the old ship.
More important was that the new Establishment in 1719 was not simply limited to specifying the overall dimensions of each type of warship, but now set out in great detail other factors used in constructing the ship, down to the thickness of timbers ("scantlings") used in construction and planking.
The Establishment adopted in 1719 was subject to substantial revisions in both 1733 and 1741, although on neither occasion was the 1719 Establishment replaced. A new Establishment was finally adopted in 1745.
Before the 1745 centralised all design work in the office of the Surveyor of the Navy, the design of every vessel was the responsibility of the Master Shipwright in the dockyard in which that vessel was built; thus ships built to one Establishment has to conform to the dimensions and other measurements specified by that Establishment, but were to varying designs and therefore did not constitute a "class" in the modern use of the term. The exception to this was when ships were built under contract by commercial shipbuilders, for which a common design was prepared by the Surveyor and copies sent to the shipbuilder for execution; this only applied to some of the two-decker ships and smaller vessels (all three-deckers were built or rebuilt in the Royal Dockyards), and was almost exclusively a wartime occurrence.
Read more about 1719 Establishment: Background, 1719 Arrangements, 1733 Proposals and Revisions, 1741 Proposals and Revisions, Individual Ship Types