Fourth-rate

In the rating system of the Royal Navy used to categorize sailing warships in the 18th century, a fourth-rate was a ship of the line with 46 to 60 guns mounted.

50-gun ships were also suitable as convoy escorts and for service on foreign stations, where larger enemy vessels were unlikely to be encountered.

Their usefulness was declining, however, and during the French Revolutionary and Napoleonic Wars few 50s were built, although several remained in service, especially on distant stations such as the East Indies.

American 44-gun frigates Constitution, United States and President were never in operational use armed with fewer than 50 guns including carronades, and were generally seen as equivalent to fourth-rates.

Any of these later large fourth-rate frigates threw a close-range broadside (including from their heavy carronades) far superior to the earlier two-decker 50s or even to third-rate 64s.