Field Grade Weapons
Most cannon are cast bronze, smooth bore, muzzleloading weapons, although some are breech-loading and older ones are constructed of iron bars welded and bound together. Because they are expensive and rare, many cannons are ornately carved and decorated, and larger ones often have unique names.
Name Cost Damage Weight Range Mount Crew Ready Bombard 10,000 gp 12d10 8000 lbs. 400 ft. - 6 10/4 Cannon 8,000 gp 10d10 6000 lbs. 300 ft. Very Heavy 5 6/3 Demi-cannon 6,000 gp 8d10 4000 lbs. 250 ft. Heavy 4 5/2 Culverin 4,000 gp 6d10 3000 lbs. 200 ft. Medium 3 4/2 Small culverin 2,000 gp 4d10 2000 lbs. 150 ft. Light 2 3/2 Swivel-gun 1,000 gp 2d10/4d6 200 lbs. 100 ft./25 ft. - 1 2/1
Damage: Assuming solid shot, this is the damage done on a direct hit. Cannon (with the exception of swivel-guns) cannot effectively be aimed at a specific person, but instead are aimed at a specific area with the intent of damaging a structure. Monsters that are size Huge or larger can be individually targeted (assuming they stay still for the several rounds needed to aim and fire the weapon). When a cannon hits its target area, it only does its listed damage to that 10x10x10 part of the structure, not any creature there. (On a natural 20, the cannon hits an unlucky person in that area dead on and does full damage to them as well.) However, cannons often do splash damage. If the cannon is using stone shot and firing into a stone environment (like most towns), this damage comes from stone fragments (slashing), or if the cannon is using any solid shot and firing into a wooden environment (like a ship), the damage comes from wooden shivers (piercing). Anyone in the 10×10 target area must make a DC 15 Reflex save or else take ¼ the direct damage inflicted by the shot from the fragments. For example, if a PC is hiding in a 10×10 wooden shack that is hit by a culverin inflicting 35 points of damage on the structure, he may take 8 points of fragment damage if he fails his save.
Crew: All members of the crew must have at least one rank in Profession: siege engineer.
Ready: Cannons all require the listed number of full round actions to reload and then aim with a normal crew. They must be re-aimed every time they are fired because their recoil moves them significantly out of place. If they are operated with a smaller crew than the listed minimum, the time it takes to reload them is proportionately longer.
Proficiency: All cannon require Profession: Siege Engineer (or Artillerist, or Cannoneer, or whatever you want to call it) to operate.
Inaccurate: All cannon have an inherent -4 to hit penalty due to the difficulty of aiming them precisely. This penalty may be reduced by 1 for every 5 points the gunner has in Profession: siege engineer. A gunner uses their base attack bonus, Int bonus, and other modifiers for range, vision, motion, etc. to determine their total attack bonus.
Misfire: Whenever you roll a natural 1 on an attack roll made with a cannon, the cannon might misfire. The crew chief must immediately roll a Profession: siege engineer check at DC 15 (the rest of the crew may assist). A successful check indicates that the wad simply misfired and the cannon must be reloaded. A failure by up to 5 indicates that the cannon is fouled and requires 2 full rounds to clear before it can be reloaded. A failure by up to 10 means that the cannon gains the broken condition and requires repair before further use. A natural 1 on this check means that the cannon has exploded and does its full normal damage to everyone and everything within 10 ft.
Bombard: Very large caliber front-loading cannon used in sieges. They fire hundred pound stone balls. Bombards are too large for most ships to carry. A variant of bombard that is used for indirect fire is called the mortars.
Cannon: A heavy bronze cannon firing a 36 to 50 pound shot, also known as a basilisk. These usually can only be placed on the bow mount of very large galleys.
Demi-Cannon: Also known as the cannon-perier, it fires a 24 pound shot. This is the heaviest weapon that can be fired from the side of a ship, and a large ship at that.
Culverin: The culverin is a medium cannon firing an 18 lb shot. These are the most common large weapon mounted broadside on sailing ships.
Small Culverin: Also known as the demi-culverin, this weapon fires a 10 lb shot and is suitable for mounting on many ships, including on the top deck.
Swivel-gun: Swivel-guns, which come in varieties also known as falcons, falconets, or robinets, can take a 1-2 pound solid shot or be filled with a dozen pistol shots. They do 2d10 damage with solid shot, but when loaded with pistol shot do 4d6 damage, less 2 points per range increment, in a 10×10 square. A gunner applies their Dexterity bonus to hit instead of their Int bonus with a swivel-gun.
Ammunition: stone or lead solid shot are the most common ordnance in cannon. There is also chain or bar shot which is effective against rigging (normal solid shot passes through rigging doing only minimum damage). Grapeshot or canister shot can also be used; this does not do structural damage but targets the crew, doing half the listed damage to all crew in a 10x10x10 area.
Taking the Stormwrack method of doing ship damage, where e.g. a caravel has 24 hull sections with hardness 5 and 80 hp each, and six must be destroyed to sink the ship – it requires 3-4 good hits with a culverin to destroy one 10x10x10 section. Given that the cannon can only fire slightly better than once a minute, that’s a good balance of enough damage with promoting resolution by boarding and melee. A heavily armed small carrack might sport 2 culverins below and 5 demi-culverins on deck per side, which at that rate could sink a ship of its class but only with some work.
Example of cannon fire: A pirate sloop approaches a merchant caravel and decides to soften them up a bit before closing. They aim their two starboard culverins and fire. The base AC to shoot a caravel is -3 because it’s just a big ass object really (value taken from Stormwrack), or AC3 if you want to shoot at a specific section. In this case the pirates just want to hit wherever on it to demoralize the crew. The ships are 200 yards apart, which is three range increments out for the culverin (-6 range). There is a moderate wind (no penalty) and both the firing platform and the target are moving (-5 for each, says Stormwrack, though that seems high ). Total AC to hit is 13. The master gunner (+5 BAB, +2 Int, 10 ranks in Prof: SE) and a crew of three is manning one gun and a bunch of gunner pirate mooks (+2 BAB, +0 Int, 3 ranks in Prof: SE) are manning the other. So the two shots are +5 vs AC 13 (about a sure thing) and -2 vs AC 13 (hit about half the time).