Carronades: Myths And Realities Of The Guns That Changed Naval Battle

By Mark N. Lardas

Spring 2004 - Vol 25, No. 2





The carronade defined the great age of fighting sail – the years between the American Revolution and the War of 1812. The carronade fit the tactics of that day almost perfectly. Short-ranged yet hard-hitting, it was the ideal weapon for the gunwale-to-gunwale combat characterizing naval combat during Nelson’s era.

Today, it is viewed as a seagoing shotgun – inaccurate and effective only at ranges too short to require aiming. This stereotype is only partly true.

The carronade actually had a greater range than commonly believed. It could throw a ball with greater accuracy than a long gun, which may paradoxically have contributed to its reputation for inaccuracy. And, it was the first scientifically designed artillery piece.

Carronades are short-barreled guns, but not all short-barreled guns are carronades. True carronades share five characteristics:

• The powder chamber is smaller than the bore for the ball.

• The bore has a smaller windage than a conventional 18th-century long gun for the same size ball.

• There is no muzzle swell.

• The gun has a sleeve with a screw jack on the cascable to elevate and lower the gun.

• The gun attaches to the carriage with a lug rather than a trunnion.

There were exceptions. Prototype carronades manufactured between 1775 and 1778 had a tiller instead of a cascable, and were cast with trunnions. These proved unsatisfactory. The Carron Company modified its design in 1778. Except for these early carronades guns lacking some or all of these traits are more properly termed gunnades, gunades, or insurance guns.

The carronade’s development reads like a 20th-century technothriller rewritten for 18th-century Britain.

The Carron Company of Falkirk, Scotland, was one of the world’s first multinational conglomerates. If it was made of iron, Carron made it. If Carron made it they sold it, through a network of worldwide agents. In 1761 Carron branched into artillery.

Early Carron cannon frequently failed proof firing. In 1764 and 1765 one-third of Carron’s production failed proof. In 1773 the British Board of Ordnance terminated Carron’s contract and ordered all Carron cannons removed from Royal Navy ships.

Carron investigated new means of casting and boring cannon and incorporated the results into their manufacturing processes. Soon, Carron was producing new long guns, lighter yet stronger than their competitors’ ordnance, and these guns passed proof. By 1778, Carron had restored its reputation in gunfounding.

Charles Gascoigne, a managing partner at Carron, applied Carron’s research to develop a new type of gun. He proposed a new lightweight, short-barreled weapon that threw a greater weight of shot than conventional guns of the same weight.

This gun used a bore built to tighter tolerances than contemporary cannon, resulting in a tighter fit when the ball was placed. Reducing windage reduced balloting – the ball bouncing from one side of the bore to the other while traveling through the barrel.

The barrel could be shortened without sacrificing accuracy. Reducing windage also reduced the gas escaping when the gun was fired. Less gunpowder was required to fire the ball. The charge was placed in a smaller chamber at the breech end of the bore focusing the thrust down the length of the barrel. These innovations allowed a thinner, lighter barrel.

Better knowledge of metallurgy also let Carron cast the barrel thinner at the muzzle, again reducing weight. Carron made a weapon capable of firing a 24-pound shot that weighed no more than a conventional 4-pdr. cannon. Mounted on a slide system to absorb part of the shock of firing, the piece had less recoil than a conventional gun – much less. The weapon was named a carronade.

The first carronades cast fired a 68-pound or a 100-pound ball. The 68-pdr. carronade eventually went into production. The 100-pdr. carronade did not. Commercial success was achieved at the other end of the spectrum, however. By September 1778 Carron was producing and selling carronades capable of firing 12-pound and 18-pound shot.

Initially carronades were used aboard commercial craft. Glasgow merchants purchased carronades for their merchantmen. In November 1778, owners of the privateer Spitfire armed the ship with 18 carronades. The ship was in several successful actions over the next few months, which proved the best publicity that Carron could get. Soon Carron was flooded with commercial orders for carronades.

The advantage of carronades on merchant and privateering vessels was obvious. Lighter and smaller than conventional guns, carronades allowed a ship owner to sacrifice less storage space and tonnage on guns. Carronades were light enough to be placed on a regular deck without the reinforcement needed for long guns. Carronades required a smaller crew, ideal for both privateers and merchant craft. The short range hardly mattered. Neither merchantman nor privateer was likely to fire a broadside at a foe more than 50 yards away.

The advantage of carronades on naval vessels was less apparently obvious. Most warships had upper decks too light for standard guns. Carronades could be placed on these without crashing through the deck.

On July 16, 1779, the Navy Board created an establishment of carronades on Royal Navy ships. It armed otherwise unused portions of deck, significantly increasing the firepower of British warships, especially frigates and sloops. A 38-gun frigate with a broadside of 282 pounds now threw 372 pounds of metal, nearly one-third more. A 16-gun sloop armed with 6-pdr. long guns doubled its broadside from 48 pounds to 98 pounds with the addition of four 12-pdr. carronades per side.

Not all captains liked the new gun. The short length of the first carronades put the mizzen shrouds at hazard when the guns were mounted on the quarterdeck. Early carronades occasionally dismounted when fired at extreme angles forward or aft. But by 1780, opinion had turned in favor of the carronade. After the captains of the 36-gun frigate Flora and 74-gun ship-of-the-line Edgar attributed victories, in part, to their carronades, the carronade’s popularity soared.

Carron added a new 24-pdr. carronade in 1779. By 1781 Carron lengthened the carronade and produced sizes capable of firing 32-pound and 42-pound shot, filling out the six standard carronade sizes of 12, 18, 24, 32, 42 and 68 pdr.

Soon captains were asking to replace upper deck long guns, especially the light 3-, 4-, and 6-pdr. guns, with carronades. A carronade was inferior to a long gun firing the same shot. A 32-pdr. carronade had half the range of a 32-pdr. long gun. The barrel of the 32-pdr. carronade weighed around 2,000 pounds, less than an 8-pdr. long gun. It could fire almost as far as an 8-pdr., however.

Substituting a carronade for a long gun with an equivalent barrel weight increased the broadside weight of metal without significantly reducing the broadside’s effective range. Frigate captains replacing upper deck 6-pdr. long guns with 24-pdr. carronades, or sloop commanders switching 18-pdr. carronades in place of 4-pdr. long guns, improved firepower without penalty.

A captain should have given up only a little range by substituting heavy carronades for light long guns. A 68-pdr. carronade had a point-blank range of 260 yards – comparable to the 300-yard range of the slightly lighter 12-pdr. long gun. Yet carronades rarely hit targets much farther than 50 to 100 yards.

Geometry and 18th-century naval gunnery may explain why. Even the Royal Navy and United States Navy rarely practice-fired guns. Between December 1792 and November 1793 HMS Victory used more gunpowder for salutes than for gunnery practice. Gunnery drill consisted of running out and dry-firing the guns. Eventually gun crews could load, run out and fire their guns three times in two minutes. Occasionally exercises ended with the guns actually loaded with powder and fired.

Aimed fire at a mark was rarer. Between December 1792 and November 1793 HMS Victory used only 50 12-pound shot in target practice – generally firing only five times per month. Target firing was only done with long guns. Any practical experience – outside of combat – was achieved on long guns.

Eighteenth-century naval battles tended to be close affairs. Beyond point-blank range a crew that had not fired at a mark would likely miss. The gun captain sighted along the top of the gun, firing when the ship’s roll brought the target in sight.

With a long gun, you were aiming the gun about 1 degree high, but within 300 yards the error was small enough. You still hit the ship’s side. A carronade aimed in such a manner would miss.

The carronade lacked a muzzle swell. It was thicker at the breech than the muzzle. Sighting along the top of the barrel aimed the gun as much as 5 degrees higher than the point of aim. At 100 yards, balls flew 25 feet higher than aimed – enough to fly over an enemy ship, especially when fired from a quarterdeck or a forecastle. Even a more modest 2 degree offset would cause the ball to fly over 10 feet above its aim point.

In an 18th-century naval battle ships fired scores of guns in a broadside with crews trained for speed rather than accuracy. The fall of shot was likely to be unobserved once the engagement became general. Both ships created clouds of smoke obscuring vision. It would be unsurprising if, under those circumstances, the carronade’s performance over 50 yards was blamed on inherent inaccuracy.

By the start of the 19th century captains were experimenting with sights that aligned the sight with the bore. By then, the carronade had two other problems. Carronades were being substituted for long guns inappropriately and technology used in carronades was being used in long guns.

When the swapped-out long guns weighed more than the carronades replacing them, the ship lost striking power. Yet by 1783, several British frigate captains requested 24-pdr. carronades in lieu of the 18-pdr. long guns established for the class. Perhaps fortunately for these captains, the war ended before these ships saw major combat.

The trend continued in the 1790s and later. Carronades were substituted for increasingly larger long guns, especially in the Royal Navy and the new United States Navy. While 4-pdr. long guns had been replaced with 24-pdr. carronades, the 12-pdr. and 18-pdr. long guns swapped out for carronades on frigate decks were being replaced with 32-pdr., or rarely, 42-pdr. carronades. A more even swap, based on barrel weight, substituted a 68-pdr. carronade for a 12-pdr. long gun and the never-produced 100-pdr. carronade for the 18-pdr. long gun.

It is difficult for one person to handle a ball weighing more than 32 pounds on a heaving deck. Navies rarely mounted guns larger than 32 pdr. Both the 42-pdr. and 68-pdr. carronades were unpopular guns. The Royal Navy probably mounted 68-pdr. carronades on no more than six warships during the Napoleonic Era. The USS Constitution carried 42-pdr. carronades during its fight with HMS Java but replaced these with 32-pdr. carronades during its 1815 cruise.

Good captains realized this. David Porter protested the replacement of the main deck 12-pdr. long guns on the USS Essex, a 32-gun frigate, with 32-pdr. carronades on the grounds that it would weaken his ability to fight. The Essex’s armament ultimately contributed to the defeat of that ship at Valpariso, although perhaps not as much as Porter, or the U.S. Navy, later claimed.

The lessons applied in the carronade’s development were also incorporated in conventional artillery. Lighter long guns were cast, with more metal at the breech and less at the muzzle. Intermediate-length guns, such as the Columbaid and some Blomfeld designs, were entering service by the 1810s. Navies began arming ships with guns that fired one size ball – typically 32 pounds. Long guns populated the lowest deck, and shorter, lighter versions of the 32-pdr. sat on upper decks, perhaps even carronades on the quarterdeck or poop.

The carronade soldiered on for a few years after the War of 1812, replaced in the world’s navies by newer designs that could hit harder and farther. Some migrated to land, used by frontier militia. In 1849, The Times of London insinuated that the carronade was fit only for use by pirates and slavers. Carron cast the last carronade in 1852.

Mark Lardas holds a degree in naval architecture and marine engineering and has worked on Space Shuttle software space navigation and electronic commerce. An amateur historian and a long-time ship modeler, as a freelance writer he has written extensively about modeling as well as naval, maritime and military history. He has written one book, “American Heavy Frigates, 1794-1826.” His second, a history of the Space Shuttle, will be released by Osprey in July.