thumb|300px|A 1728 diagram illustrating a first- and a third-rate ship

The rating system of the Royal Navy and its predecessors were used by the 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 the late 19th century by declaration of the Admiralty; rating ships by the number of guns had become obsolete with new types of gun, the introduction of steam propulsion and the use of iron and steel armour.

Origins and description

The first movement towards an English naval rating system began in the early 16th century, when the largest carracks in the Tudor navy, such as Mary Rose, Peter Pomegranate and Henry Grace à Dieu, were denoted as "great ships". This was due only to their size, not to their weight, crew or number of guns. When these carracks were superseded by galleons later in the 16th century, the term "great ship" was used to formally delineate the English navy's largest ships.

The Stuart era

The earliest categorisation of Royal Navy ships dates to the reign of King Henry VIII. Henry's navy consisted of 58 ships, and in 1546 the Anthony Roll divided them into four groups: "ships, galliasses, pinnaces, and row barges".

The formal system of dividing up the Navy's combatant warships into a number or groups or "rates", however, only originated in the very early part of the Stuart era, with the first lists of such categorisation appearing around 1604. At this time the combatant ships of the "Navy Royal" were divided up according to the size of the crew they required into four groups:

  • Royal Ships – the largest ships in the previous "great ships" grouping, mounting 42–55 guns and carrying at least 400 men;
  • Great Ships – the rest of the ships in the previous "great ships" grouping, mounting 38–40 guns;
  • Middling ships mounting 30–32 guns; and
  • Small ships mounting fewer than 30 guns

A 1612 list referred to four groups: royal, middling, small and pinnaces; but defined them by tonnage instead of by guns, starting from 800 to 1200 tons for the ships royal, down to below 250 tons for the pinnaces.

By the early years of King Charles I's reign, these four groups had been renamed to a numerical sequence. The royal ships were now graded as first rank, the great ships as second rank, the middling ships as third rank, and the small ships as fourth rank. Soon afterwards, the structure was again modified, with the term rank now being replaced by rate, and the former small ships now being sub-divided into fourth, fifth and sixth rates.

This classification scheme was substantially altered in late 1653 as the complements of individual ships were raised. From about 1660 the classification moved from one based on the number of men to one based on the number of carriage guns a ship carried.

A special case were the Royal Yachts, which, for reasons of protocol, had to be commanded by a senior captain. These vessels, despite their small size and minimal armament, were often classed as second- or third-rate ships, appropriate for the seniority of the captain.

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 Navy did retain some fourth rates for convoy escort, or as flagships on far-flung stations; it also converted some East Indiamen to that role. The recommendation from the Board of Admiralty to the Prince Regent was dated 25 November 1816, but the Order in Council establishing the new ratings was issued in February 1817. From February 1817 all carronades were included in the established number of guns. Until that date, carronades only "counted" if they were in place of long guns; when the carronades replaced "long" guns (e.g. on the upper deck of a sloop or post ship, thus providing its main battery), such carronades were counted.

1856 changes

There was a further major change in the rating system in 1856. From that date, the first rate comprised all ships carrying 110 guns and upwards, or the complement of which consisted of 1,000 men or more. The second rate included one of HM's royal yachts, and otherwise comprised all ships carrying under 110 guns but more than 80 guns, or the complements of which were under 1,000 but not less than 800 men.

The third rate included all the rest of HM's royal yachts and "all such vessels as may bear the flag of pendant of any Admiral Superintendent or Captain Superintendent of one of HM's Dockyards", and otherwise comprised all ships carrying at most 80 guns but not less than 60 guns, or the complements of which were under 800 but not less than 600 men. The fourth rate comprised all frigate-built ships of which the complement was not more than 600 and not less than 410 men.

The fifth rate comprised all ships of which the complement was not more than 400 and not less than 300 men. The sixth rate consisted of all other ships bearing a captain. Of unrated vessels, the category of sloops comprised all vessels commanded by commanders. Next followed all other ships commanded by lieutenants, and having complements of not less than 60 men. Finally were "smaller vessels, not classed as above, with such smaller complements as the Lords Commissioners of the Admiralty may from time to time direct".

Other classifications

Rating was not the only system of classification used. Through the early modern period, the term "ship" referred to a vessel that carried square sails on three masts. Sailing vessels with only two masts or a single mast were technically not "ships", and were not described as such at the time. Vessels with fewer than three masts were unrated sloops, generally two-masted vessels rigged as snows or ketches (in the first half of the 18th century), or brigs in succeeding eras. Some sloops were three-masted or "ship-rigged", and these were known as "ship sloops".

Vessels were sometimes classified according to the substantive rank of her commanding officer. For instance, when the commanding officer of a gun-brig or even a cutter was a lieutenant with the status of master-and-commander, the custom was to recategorise the vessel as a sloop. For instance, when Pitt Burnaby Greene, the commanding officer of in 1811, received his promotion to post-captain, the Navy reclassed the sloop as a post ship.

Practices in other navies

Although the rating system described was only used by the Royal Navy, other major navies used similar means of grading their warships. For example, the French Navy used a system of five rates ("rangs") which had a similar purpose. British authors might still use "first rate" when referring to the largest ships of other nations or "third rate" to speak of a French seventy-four. By the end of the 18th century, the rating system had mostly fallen out of common use, although technically it remained in existence for nearly another century, ships of the line usually being characterized directly by their nominal number of guns, the numbers even being used as the name of the type, as in "a squadron of three seventy-fours".

United States (1905)

As of 1905, ships of the United States Navy were by law divided into classes called rates. Vessels of the first rate had a displacement tonnage in excess of 8000 tons; second rate, from 4000 to 8000 tons; third rate, from 1000 to 4000 tons; and fourth rate, of less than 1000 tons. Converted merchant vessels that were armed and equipped as cruisers were of the second rate if over 6000 tons, and of the third rate if over 1000 and less than 6000 tons. Auxiliary vessels such as colliers, supply vessels, repair ships, etc., if over 4000 tons, were of the third rate.

Auxiliary vessels of less than 4000 tons—except tugs, sailing ships, and receiving ships which were not rated—were of the fourth rate. Torpedo-boat destroyers, torpedo boats, and similar vessels were not rated. Captains commanded ships of the first rate. Captains or commanders commanded ships of the second rate. Commanders or lieutenant-commanders commanded ships of the third rate. Lieutenant-commanders or lieutenants commanded ships of the fourth rate. Lieutenant-commanders, lieutenants, ensigns, or warrant officers might command unrated vessels, depending on the size of the vessel.