In the rating system of the British Royal Navy used to categorise sailing warships, a first rate was the designation for the largest ships of the line, equivalent to the 'super-dreadnought' of more recent times. Originating in the Jacobean era with the designation of Ships Royal capable of carrying at least 400 men, the size and establishment of first-rates evolved over the following 250 years to eventually denote ships of the line carrying at least 80 guns across three gundecks. By the end of the eighteenth century, a first-rate carried no fewer than 100 guns and more than 850 crew, and had a measurement (burthen) tonnage of some 2,000 tons.