SHIP COMBAT RULES EXTERNAL LINK
Shipboard Weapons
Shipboard weapons can be attacked independently of the ship they're on, and unlike ships they are not immune to melee and ranged attacks from creatures. A shipboard weapon typically has the following statistics: hp 80, AC 25, Fortitude 25, Reflex 0.
A standard shipboard weapon requires a crew of two to operate: one to load and aim the weapon (standard action) and one to fire and reset it (standard action). The range is given in 100-foot squares (as opposed to 5-foot squares).
Ballista (500 gp): Ranged 5/10; +15 vs. AC (+13 while the ship is bloodied). Hit: 3d10 damage.
Catapult (500 gp): Ranged 10/20; +13 vs. AC (+11 while the ship is bloodied). Hit: 5d10 damage.
Magical variants of standard shipboard weapons are also available. Magical weapons deal +5 damage per enhancement bonus on a hit, and they often have rider effects such as ongoing damage, damage on a miss, or some other effect. Some magical variants require ammunition, while others don't. Here are some examples of magical shipboard weapons:
+1 flameshot ballista (Level 10; 5,000 gp): Ranged 5/10; +16 vs. AC (+14 while the ship is bloodied). Hit: 3d10 + 5 fire damage, and ongoing 5 fire damage (save ends).
+2 thundershot ballista (Level 15; 25,000 gp): Ranged 5/10; +17 vs. AC (+15 while the ship is bloodied). Hit: 3d10 + 10 thunder damage, and the target ship loses 1 action on its next turn.
+1 shrapnel catapult (Level 10; 5,000 gp): Ranged 10/20; +14 vs. AC (+12 while the ship is bloodied). Hit: 5d10 + 5 damage, and roll 2d6: On doubles, the target ship loses a number of crew equal to the highest die result.
+2 splintershot catapult (Level 15; 25,000 gp): Ranged 10/20; +15 vs. AC (+13 while the ship is bloodied). Hit: 5d10 + 10 damage. Miss: 15 damage.
Damage and Repair
A ship has hit points and defenses like any vehicle. However, a ship can only be damaged by shipboard weapons as well as close and area attacks that damage objects. While a ship is bloodied, attacks made aboard the ship (including attacks made with its shipboard weapons) take a –2 penalty.
A damaged ship can be repaired at a cost of 100 gp per hit point, provided there's equipment and replacement parts available to complete the repairs. Each hit point of damage requires 1 man-hour to repair.
Basic Combat Rules
Ship-to-ship combat plays out on a standard 1-inch-square grid, but each square represents roughly 100 feet (20 squares at character scale). Each ship occupies a single square.
Initiative: At the start of ship-to-ship combat, each captain rolls initiative. A ship’s initiative modifier is the same as its captain’s (+0 if the ship has no captain).
Movement: A ship moves its speed before and after taking actions (described below). If the ship has less than minimal crew, it moves at half speed.
Crew: A ship with less than minimal crew moves at half speed and loses 3 actions per turn.
Bloodied: When a ship is first bloodied in an encounter, one of its weapons (determined randomly) is destroyed. While a ship is bloodied, the ship and all creatures aboard take a –2 penalty to attack rolls.
Actions: On its turn, between moves, a ship gets 5 actions (–2 actions if its captain is absent, helpless or dead, and –3 actions if the ship has less than a minimal crew). Actions include making a skill check to gain a tactical advantage, firing a shipboard weapon, and ramming. As a matter of protocol, the captain usually decides how many weapons to fire versus how many skill checks to make on a ship’s turn. Ramming is a special action, described below.
Types of Actions
Making a Skill Check: Skill checks must be resolved before making attacks with shipboard weapons. Making a skill check in ship-to-ship combat costs 1 action regardless of whether or not the check succeeds. No skill may be used more than once on a ship’s turn. The skill check is made by a crew member — either a player character or a nonplayer character. The aid another rule applies, as normal.
The following skills apply:
Acrobatics (DC high): Your evasive instincts kick in. Your ship gains a +2 bonus to AC and Reflex until the start of its next turn.
Arcana (DC high): You manipulate subtle arcane energies to fortify your ship. Your ship gains 10 temporary hit points as well as a +2 bonus to Fortitude until the start of its next turn.
Athletics or Nature (DC medium): You command the rigging or harness the winds to your advantage. Your ship can move 1 square before each shipboard weapon attack it makes this turn.
Bluff (DC high): You mislead the enemy. The enemy ship loses 1 action on its next turn.
Diplomacy or Intimidate (DC medium): You coordinate the attack on the enemy. Any attack made by your ship until the end of its next turn deals half damage on a miss.
Diplomacy or Intimidate (captain only; DC high): You motivate the crew in ways your enemy cannot. Until the end of this turn, whenever your ship makes an attack using a shipboard weapon, make two attack rolls and use the higher result.
History or Insight (DC medium): You are versed in naval battle tactics and can anticipate your enemy’s maneuvers. Your ship gains a +2 bonus to attack rolls until the end of its current turn.
Perception (DC high): You see a structural weakness or tactical flaw that can be exploited. Until the end of your current turn, the enemy ship gains vulnerable 10 to your ship’s attacks.
Religion (DC high): You call upon Melora, the Harridan, or some other great power to grant you favor in battle. Until the end of your current turn, your ship scores a critical hit on a natural roll of 18, 19 or 20.
Firing a Shipboard Weapon: Attacks are resolved after skill checks, and firing a shipboard weapon costs 1 action. Unless noted otherwise, no shipboard weapon may be fired more than once on a ship’s turn, and ranged shipboard weapons can be fired without provoking opportunity attacks from adjacent ships.
Critical Hits with Shipboard Weapons: A critical hit deals maximum damage plus 1d10 extra damage per enhancement bonus of the weapon. As an option, the attacker can choose to treat the critical hit as a normal hit and also reduce the target vessel’s speed by 1. Whenever a ship takes a critical hit, roll 3d6: If you roll doubles or triples, the ship loses a number of crew equal to the highest die result. (For example, if you roll a 2, 2, and 5, the ship loses 5 crew.) A player character aboard the target ship can, as an immediate action, spend a healing surge to negate 1 crew casualty.
Ramming: Ramming another ship costs 3 actions. The ramming ship, which must be at least 2 squares away from the enemy ship at the start of the ram, immediately moves a number of squares up to its speed into a space adjacent to the enemy ship. If it cannot reach an adjacent square, it cannot perform the ram action. The ramming ship then makes an attack (+0 vs. Reflex) against the enemy ship. Apply a –5 penalty to the attack if the ramming ship has less than a minimal crew. If the ram attack succeeds, both ships take the specified amount of damage, and neither ship can take actions on its next turn.