Fourth Rate

HMS Experiment (Fourth Rate, 46 guns)

Fourth Rates featured a single gun deck with cannons mounted on both broadsides, supplemented by quarterdeck and forecastle armaments. The hull design prioritized stability over pure speed; full-bodied construction enabled cargo capacity alongside military armament. Rigging employed three masts with square sails on fore and main, fore-and-aft gaff sails on the mizzen. Steering was by whipstaff or early wheel mechanisms. These vessels could achieve 9–11 knots in favorable wind, sufficient for escort duties and pursuit of merchant raiders.

The Fourth Rate emerged in the 1660s as navies standardized ship classifications. Too large for frigate duties, too small for line-of-battle service, Fourth Rates filled a critical gap: they defended trade routes, escorted convoys, and patrolled colonial coasts. The Royal Navy maintained 20–30 Fourth Rates throughout the Golden Age. Privateers occasionally captured or chartered these vessels; pirate captains rarely commanded them, lacking resources for such expensive ships. By 1720, steam-era designs rendered them obsolete.

Colonial expansion and merchant-convoy warfare demanded mid-sized warships. Fourth Rates cost less than 60-gun Third Rates yet carried sufficient armament to deter privateers and pirates. They operated in shallow colonial waters where larger ships-of-the-line could not venture. Insurance companies and merchant consortiums funded convoy escorts; navies deployed Fourth Rates to protect national trade monopolies and suppress piracy in the Caribbean, Indian Ocean, and Atlantic approaches.

A Fourth Rate's day began with dawn watch rotations and gun-crew drills. Sailors holystoned decks, maintained rigging, and checked cannon trunnions. Officers navigated by dead reckoning and celestial observation. Gunnery practice occurred weekly; powder and shot were inventoried monthly. Meals were served at noon (salt beef, hardtack, beer) and evening (pottage, cheese). Off-watch crew repaired sails, caulked seams, and tarred rope. In combat readiness, gun crews stood by their pieces; marines mustered on quarterdeck. Illness—scurvy, dysentery, typhus—claimed more sailors than enemy action.

Fourth Rates were built in royal dockyards (Portsmouth, Chatham, Deptford) and private shipyards. Oak frames were cut to compass-timber specifications; planking was English or Baltic oak, 3–4 inches thick. The keel was laid in a building slip; frames were erected, then planked from keel to gunwale. Gun ports were sawn after launching. Caulking with oakum and pitch sealed seams. Copper sheathing (introduced c.1708) protected hulls from teredo worms in tropical waters. Construction took 18–24 months; cost ranged from £4,000–£8,000 sterling.

The 46-gun Fourth Rate (smaller, faster) differed from the 60-gun variant (heavier, more powerful). Some vessels mounted 50 guns in mixed calibers (12-pounders, 6-pounders, 4-pounders). Swedish and Dutch Fourth Rates had slightly different proportions and rigging. French Fourth Rates (e.g., Médée-class) emphasized speed. Privateer-owned Fourth Rates sometimes carried fewer guns and extra cargo space. By 1715, some Fourth Rates were rebuilt with reinforced hulls and updated gun carriages.

Few Fourth Rates have been archaeologically excavated. HMS Shoreham wreck (discovered off Jamaica, 2003) yielded iron cannons, pewter plates, and navigational instruments. Ballast stones and copper fastenings from unidentified Fourth Rate wrecks have been recovered in Caribbean surveys. No intact Fourth Rate hull survives; most were broken up for timber by 1750. Documentary evidence (muster rolls, dockyard records) at the National Archives (Kew) provides construction and service details.