1817 Changes
In February 1817 the rating system changed. 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.
Read more about this topic: Rating System Of The Royal Navy