The Adventure-class ship was a class of eight 44-gun sailing two-decker warships of the Royal Navy, classed as a fifth rate like a frigate, but carrying two complete decks of guns, a lower battery of 18-pounders and an upper battery of 12-pounders. This enabled the vessel to deliver a broadside of 318 pounds.
The class was designed in 1782 by Edward Hunt, Surveyor of the Navy, as a successor to the Roebuck class design of Sir Thomas Slade. The design saw a slight increase in breadth over the Roebuck class, but was otherwise very similar.
Like the Roebuck class, the Adventure class were not counted by the Admiralty as frigates; although sea officers sometimes casually described them and other small two-deckers as frigates, the Admiralty officially never referred to them as such. By 1750, the Admiralty strictly defined frigates as ships of 28 guns or more, carrying all their main battery (24, 26 or even 28 guns) on the upper deck, with no guns or openings on the lower deck (which could thus be at sea level or even lower). A frigate might carry a few smaller guns – 3-pounders or 6-pounders, later 9-pounders – on their quarterdeck and (perhaps) on the forecastle. The Adventure-class ships were two-deckers with complete batteries on both decks, and hence not frigates.
Eight ships were ordered during 1782 and completed to this design, although none were ready to take part in the American War of Independence. Most were not brought into service until the outbreak of the French Revolutionary War, and survived to serve the Royal Navy during the Napoleonic War.