Information about siege weapons mounted on Ships

Information about siege weapons mounted on Ships:
Stats for Siege Weapons used in Ships
All Ships descriptions should include how many siege weapons it can mount. Convert this weapons to Siege Weapon Slots with the following formula:

  • Light Ballista = 1 slot
  • Heavy Ballista = 2 slots
  • Light Catapult = 2 slots
  • Heavy Catapult = 4 slots
  • Light Weapon = 1 slots
  • Heavy Weapon = 2 slots
    The numbers of slots can be used to allocate siege weapons using the same formula.
    For example: A ship that allows for 1 Light Catapult and 1 Heavy Catapult can be converted to 6 slots. This could be used for 3 Light Catapults or 6 Light Ballistas.

In addition Complement and Cargo capacity can be reduced by 10% to gain one additional slot. The maximum allowed is 3 slots or 30%.

The following rules and stats apply to siege weapons used in Ships and on land.

Skills & Feas
Firing a siege weapon requires a Profession (siege engineer) check or a normal range attack at – 4 using the Intelligence modifier instead of the Dexterity modifier and any range increments or special modifiers that apply. Skills and Feats needed to use siege weapons without a – 4 penalty are:

  • Skill: Profession (Siege Engineer)
  • Feat: Siege Engineer Feat

A Siege Weapon requires a full crew to reload and fire the weapon once per turn. Per each less crew member, the weapon takes an additional combat turn to be prepared and fired. For example: Loading a catapult requires a series of full-round actions. It’s assumed that each member of the siege weapon is doing its part. It takes a DC 15 Strength check to winch the throwing arm down; most catapults have wheels to allow up to two crew members to use the aid another action, assisting the main winch operator. A DC 15 Profession (siege engineer) check latches the arm into place, and then another DC 15 Profession (siege engineer) check loads the catapult ammunition. It takes four full-round actions to re-aim a heavy catapult (multiple crew members can perform these full-round actions in the same round, so it would take a crew of four only 1 round to re-aim the catapult).

A indirect weapon that misfires will still hit somewhere. Roll 1d8 to see which of the 8 squares around the original target and a 1d6 + 1 per each point the roll is missed to see how many squares away it lands. Damage is rolled normally.

Direct vs Indirect Fire Weapons

  • Direct Fire Weapons – Ballistas attack just like crossbows, they attack directly to the target. They use the target’s normal AC. Been a ship or a creature.
  • Indirect Fire Weapons – Catapults attack with a DC of 10 if the target is on land, the AC of the ship, or a touch attack if attacking a creature. When a catapult pitch hits a spot it does normal damage to the square it hits and half damage to all squares around it. Characters on the adjacent squares can make a Reflex save (DC: 15) for half damage.


  • No line of sight to target square ( – 6)
  • Successive shots (crew can see where most recent misses landed) – Cumulative + 2 per previous miss (maximum + 10)
  • Successive shots (crew can’t see where most recent misses landed, but observer is providing feedback) – Cumulative + 1 per previous miss (maximum + 5)

Dungeon Master Guide 3.0
Arms and Equipment Guide
Stronghold Builders
Forgottten Realms

Information about siege weapons mounted on Ships

D&D 3.0: Tales from Mystara Galero