The rating system of the Royal Navy and its predecessors was used by the British Royal Navy between the beginning of the 17th century and the middle of the 19th century to categorise sailing warships, initially classing them according to their assigned complement of men, and later according to the number of their carriage-mounted guns. The rating system of the Royal Navy formally came to an end in 1876 by declaration of the Admiralty.
First, second and third rates (ships of the line)
A first-, second- or third-rate ship was regarded as a “ship-of-the-line”. The first and second rates were three-deckers; that is, they had three continuous decks of guns (on the lower deck, middle deck and upper deck), usually as well as smaller weapons on the quarterdeck, forecastle and poop.
The largest third rates, those of 80 guns, were likewise three-deckers from the 1690s until the early 1750s, but both before this period and subsequent to it, 80-gun ships were built as two-deckers. All the other third rates, with 74 guns or less, were likewise two-deckers, with just two continuous decks of guns (on the lower deck and upper deck), as well as smaller weapons on the quarterdeck, forecastle and (if they had one) poop.
A series of major changes to the rating system took effect from the start of January 1817, when the carronades carried by each ship were included in the count of guns (previously these had usually been omitted); the first rate from that date included all of the three-deckers (the adding in of their carronades had meant that all three-deckers now had over 100 guns), the new second rate included all two-deckers of 80 guns or more, with the third rate reduced to two-deckers of fewer than 80 guns.
Fourth, fifth and sixth rates
The smaller fourth rates, of about 50 or 60 guns on two decks, were ships-of-the-line until 1756, when it was felt that such 50-gun ships were now too small for pitched battles. The larger fourth rates of 60 guns continued to be counted as ships-of-the-line, but few new ships of this rate were added, the 60-gun fourth rate being superseded over the next few decades by the 64-gun third rate.
The smaller two deckers originally blurred the distinction between a fourth rate and a fifth rate. At the low end of the fourth rate one might find the two-decker 50-gun ships from about 1756. The high end of the fifth rate would include two-deckers of 40- or 44-guns (from 1690) or even the demi-batterie 32-gun and 36-gun ships of the 1690–1730 period. The fifth rates at the start of the 18th century were generally “demi-batterie” ships, carrying a few heavy guns on their lower deck (which often used the rest of the lower deck for row ports) and a full battery of lesser guns on the upper deck.
Fifth and sixth rates were never included among ships-of-the-line. The middle of the 18th century saw the introduction of a new fifth-rate type—the classic frigate, with no ports on the lower deck, and the main battery disposed solely on the upper deck, where it could be fought in all weathers.
Sixth-rate ships were generally useful as convoy escorts, for blockade duties and the carrying of dispatches; their small size made them less suited for the general cruising tasks the fifth-rate frigates did so well. Essentially there were two groups of sixth rates. The larger category comprised the sixth-rate frigates of 28 guns, carrying a main battery of twenty-four 9-pounder guns, as well as four smaller guns on their superstructures. The second comprised the “post ships” of between 20 and 24 guns. These were too small to be formally counted as frigates (although colloquially often grouped with them), but still required a post-captain (i.e. an officer holding the substantive rank of captain) as their commander.
Unrated vessels
The rating system did not handle vessels smaller than the sixth rate. The remainder were simply “unrated”. The larger of the unrated vessels were generally all called sloops, but that nomenclature is quite confusing for unrated vessels, especially when dealing with the finer points of “ship-sloop”, “brig-sloop”, “sloop-of-war” (which really just meant the same in naval parlance as “sloop”) or even “corvette” (the last a French term that the British Navy did not use until the 1840s). Technically the category of “sloop-of-war” included any unrated combatant vessel—in theory, the term even extended to bomb vessels and fire ships.
During the Napoleonic Wars, the Royal Navy increased the number of sloops in service by some 400% as it found that it needed vast numbers of these small vessels for escorting convoys (as in any war, the introduction of convoys created a huge need for escort vessels), combating privateers, and themselves taking prizes.
