Evolution of the Naval Gun

The late 15th century that saw the introduction of shipboard ordnance, but it was the early 16th century that was witness to the proliferation of larger ship killing guns (at sea the term is guns, never cannon).

The ‘port peece’ – so called as it protruded through the recently developed gun port – had a barrel made up of welded wrought iron staves forming a tube, further held in place by iron hoops sweated on round the outside, the joins between being sealed with lead, resulting in a barrel open at both ends. A separate detachable breech chamber would be wedged into the end to contain the powder charge, set in a wooden bed sitting firstly on feet then latterly ‘trucks’ (wheels at the muzzle end which would absorb the recoil). The whole contrivance would be tied together with rope ‘wooldings’. At this stage, guns fired hewn stone shot weighing up to 25lbs.

Before the first quarter of the 16th century was out, this ‘bar barrel’ type of gun was superseded by the ‘bobbin’ gun – similar to the previous design but made up of short lengths of iron tubes, again held in place by iron hoops where the ends met. These guns were around 7.5 feet (2.25m) long, with a bore of between 5-8 inches (12.5 – 20.5 cms).

The gun was prepared for firing by priming the ‘touch’ or vent aperture with priming powder then igniting this, followed by the main charge with a slow match wrapped around a wooden rod. This was often decorated with a snake or a lion’s mask called a linstock and was usually 1 yard long (90cms).

The next step in gun design was something of a quantum leap with the advent of the cast bronze one-piece gun of the mid-16th century. These new guns did away with the breech block, sitting on a two-truck carriage rather than a bed, and being fashioned in bronze as at this time iron couldn’t be heated sufficiently to be poured into a mould. They differed from later guns in that they were shorter in the chase, lighter and thinner in relation to bore, and fired 18 to 32 lbs cast iron round shot and were muzzled loaded.  

Next came the culverin and demi-culverin of the 17th century. These were the most common type in the Royal Navy until the early 18th century and were 18 and 9 pounders respectively, still cast in bronze, usually with integral lifting lugs known as ‘dolphins’ as they were often shaped thus. They were muzzle loaded and sat on four truck carriages usually of elm or oak and ranged in length from 8 to 11 feet (2.43 to 3.35m).

In the 18th century improved smelting and casting processes meant iron could now be used for producing cast guns. In 1725 John Armstrong – Surveyor General of the Royal Navy – designed a completely new type of gun; the ‘Armstrong’ 18 pounder. It was larger and more robust than its bronze predecessors, with variations  including 24 and 32 pounders. It would last up until 1793.    

Captain Sir Thomas Blomefield , Inspector of Artillery from 1780, resolved to improve on the Armstrong design by making the breech thicker, the chase thinner and adding a loop to the top of the cascabel button, thereby making it much easier to secure to the ship’s sides. These ‘Blomefield’ guns would be the standard main battery gun from around 1793 until rifled and shell firing guns appeared in mid-19th century.

The mortar, first deployed aboard French ships in 1682 during the bombardment of Algiers, fired an exploding shell (a hollow iron ball filled with gunpowder, fitted with a short fuse) from it’s very wide, but squat, barrel. In its’ 150  or so years of use it didn’t evolve or change much. The 10-inch gun (25.5 cm) weighed 18 cwt (914 kg) and its’ shell 93lbs (41 kg) whilst the later 13 inch (33 cm) weighed 81 cwt (4115 kg) and its’ shell was 198lbs (90 kg).

From the mortar the carronade was developed, in Scotland at the Carron iron foundry near Falkirk and was first adopted by the Royal Navy in 1779. Early patterns were much like shortened long guns, but it was redesigned during the peace of 1783 – 93. Now there was a loop underneath the 5-foot-long barrel instead of trunions, a screw elevation in place of quoins, and a slide carriage. Being lighter than the long gun they could be mounted higher up without compromising stability although their weight of shot ranged between 32 and 68lbs. 

By Justin Dempster, HMS Unicorn Volunteer