Carronade

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Current revision as of 10:04, 24 November 2010

Carronades were a type of lightweight cannon introduced in 1778 by Carron Foundry of Falkirk, Scotland, principally for use at sea. Carronades were designed to achieve a significant saving of both weight and manpower over standard ('long') guns. This was achieved in three principal ways:

• The cast-iron barrel was much shorter than that of a standard gun and consequently lighter. The overall weight of a 32-pound long gun was about 55 hundredweight (2.75 imperial tons or 2.8 metric tonnes) and its length over 9 feet (2.75 metres); the figures for a carronade of the same calibre were about 17 hundredweight (865kg) and little more than 4 feet (1.22 metres) while in smaller calibres the difference was still greater.
• While the traditional gun was mounted rigidly on a four-wheeled carriage so that the entire assembly recoiled when fired, the carronade barrel was usually mounted on a bed which remained permanently in place, the recoil being absorbed by a channel or slide which allowed the barrel to move lengthways in relation to the bed (which, from this feature, was itself sometimes called a slide). This had at the inboard end two wheels, which unlike the conventional wheel or truck were designed to swivel like castors for greater ease of traversing (i.e. swinging the gun from side to side); the outer end was pivoted on a bolt screwed into the deck.
• All except the earliest carronades were fitted with a vertical threaded rod passing through the end of the cascabel, allowing the vertical angle to be adjusted much more easily than by the old method of quoin and handspike.

All this meant that a large carronade could be handled by many fewer men. For example, four or five men could handle a 42-pounder carronade, while fourteen were needed for a 42-pounder long gun, and it is said of HMS Surprise's 32-pounder carronades, generally stowed in the hold as ballast but ocassionally replacing the 12-pounder cannon, that "only a couple of hands were required to work them as opposed to the great gun's team of six or eight."^[1] Thus, a relatively small vessel could carry 24- or 32-pounder carronades without overstraining either her timbers or her crew. In fact, increasing the broadside-weight of small vessels was probably the most common use of carronades, though they were also used on the upper decks of a ship of the line, where they would give extra weight of firepower without making the ship top-heavy. E.g., the Victory carried two 68-pounders (the largest size) at Trafalgar.

Carronades were not free from drawbacks: the short barrel, projecting only a little way beyond the gun-port when run out, created some risk of setting the vessel's own rigging on fire, and (more seriously) it considerably reduced the effective range of the gun from the typical maximum range of 1.5 miles (perhaps 750 yards with high accuracy) for a long gun to a maximum accuracy of 250 yards for a carronade. Nonetheless, these guns (distrusted at first, partly because of initial faults in the casting process and partly through the innate traditionalism of the Navy) came to be very popular in the fleets of all nations. Napoleon, who as a former artillery specialist may be considered a good judge of this aspect of naval practice if not of any other, had a particular liking for carronades and constantly urged his Minister of Marine to issue more of them.

Shot weight and type

Carronades sometimes served as the principal armament of small vessels and were widely used to supplement the long gun batteries of larger vessels. Their lighter weight permitted a greater weight of broadside, with a smaller crew to handle them and fire them more rapidly. Their primary disadvantage was their somewhat shorter range and reduced accuracy. Typical specifications of carronades used in the Royal Navy were:

 Shot Wt.(lbs)	Length	   Weight (lbs)	Range at 5 degrees elevation (yds)
    12	         2’ 2”	      654	             870
    18	         3’ 3”	     1068	            1000
    24	         3’ 7.5”     1456	            1050
    32	         4’ 0.5”     1918	            1087
    42	         4’ 3.5”     2492	            1170
    68	         5’ 2”	     4032	            1280

Round shot in carronades were typically of a tighter fit (less “windage”) than in long guns, making a more efficient use of the powder charge; standard charges even for large carronades were typically only of a few pounds.

  Shot Wt.(lbs)	Shot Diameter (ins)	Bore Diameter (ins)
       12	        4.40	             4.50
       18	        5.04	             5.16
       24	        5.55	             5.68
       32	        6.10	             6.25
       42	        6.68	             6.85
       68	        7.85	             8.05

A variety of ingenious carriages were designed for carronades, with “slides” often substituted for wheels (to eliminate recoil across the deck).

References

Burney (William), New Universal Dictionary of the Marine (London, 1815), s.v. 'Carronade'. The reference to the four-man crew is from Burney, who applies it specifically to a 42-pounder (the second largest size) with a modified bed devised by Admiral Bertie.