Sloop-of-war

In the 18th and most of the 19th centuries, a sloop-of-war in the Royal Navy was a warship with a single gun deck that carried up to eighteen guns. The rating system covered all vessels with 20 guns and above; thus, the term sloop-of-war actually encompassed all the unrated combat vessels, including the very small gun-brigs and cutters. In technical terms, even the more specialised bomb vessels and fireships were classed as sloops-of-war, and in practice these were actually employed in the sloop role when not carrying out their specialized functions.

In World War I and World War II, the Royal Navy reused the term "sloop" for specialized convoy-defence vessels, including the Flower class of World War I and the highly successful Black Swan class of World War II, with anti-aircraft and anti-submarine capability.

Rigging

A sloop-of-war was quite different from a civilian or mercantile sloop, which was a general term for a single-masted vessel rigged in a way that would today be called a gaff cutter (but usually without the square topsails then carried by cutter-rigged vessels), though some sloops of that type did serve in the 18th century British Royal Navy, particularly on the Great Lakes of North America.