Naval Combat
These rules provide guidance for using ships in combat rather than each player characters and npc characters.
Ship Initiative
A ship uses its controller's initiative modifier.
On the ship's turn, the crew members on the ship who are using the ship’s initiative may take ship actions, as described below.
Crew Initiative
A crew member can choose to either use the ship’s initiative, allowing them to take ship actions, or to roll initiative themselves, allowing them to act independently but take actions such as Cannon Propulsion, Rope Acrobatics, and Naval Technique Casting, as well as whatever other actions they could take in normal combat.
Ship Movement
A creature at the helm of the ship can use their action to control the ship.
A ship can move a maximum number of spaces (50 ft each) equal to its speed.
A ship must move a number of spaces equal to its momentum, which is equal to how many spaces it moved the last turn. The ship’s controller can halve the ship’s momentum, rounding down, or double it, up to the ship’s speed, rounding up. If a ship’s momentum is 0, its controller can instead add 1 to its momentum.
As part of this movement, a ship can turn up to a number of degrees equal to 360 divided by twice the ship’s turn circle, rounded up to the nearest multiple of 45. If a ship’s turn circle is 0, the ship can turn 360 degrees. To do this the ship’s controller must make a Water Vehicles check with a bonus or penalty equal to the ship’s maneuverability modifier, with the DC equal to the number of degrees turned divided by 10, rounded up. If the ship’s controller fails this check, they turn a number of degrees equal to half of what was intended, rounded down to the nearest multiple of 45. The ship’s controller only makes one check depending on the total number of degrees turned in the ship’s turn.
If the ship’s controller does not use their action to control the ship, the ship does not turn and moves a number of spaces equal to 75% of its momentum, rounded down.
The ship’s controller cannot use multiple actions to control the ship multiple times.
Ship Actions
Player Characters and Hirelings can use their actions to take special actions for the ship. If they use the ship’s initiative. Here are example actions crew members can use:
Aim and Fire
As an action, a crew member can aim and fire one of the ship’s weapons. The weapon can be fired at an angle of up to 90 degrees off of whatever direction it’s facing. The exception to this is the Turret, which can turn a full 360 degrees before being fired. The crew member makes an attack roll using their Dexterity modifier + the tier of the ship, and on a hit deals damage equal to the weapon’s damage dice + the crew members Dexterity modifier + the tier of the ship. Ship weapons, like other ranged weapons, can be haki-imbued.
Short range weapons have a range of 2 spaces (100 ft). Medium range weapons have a range of 4 spaces (200 ft). Long range weapons have a range of 6 spaces (300 ft).
Brace
As an action, an officer can prepare the crew to brace the ship for any incoming attack or projectiles. Until the start of the officer's next turn, the ship gains +2 Armor Class and saving throws against outside projectiles being fired at it. This action can only be taken once per round by one member of the crew, and the bonus does not stack.
Full Speed Ahead
As an action, an officer can unfurl the sails or power up the engine and command the crew to work harder. Roll a 1d6 and multiply the result by 5. Apply the total as a bonus to the ship's speed and momentum until the end of the ship's next turn. If this bonus is applied to a ship's speed when the ship is already moving faster than normal, use the higher result instead. Don't add the two bonuses together. After the ship’s turn, the momentum stays the same as the number of spaces the ship moved, up to its normal speed.
Individual Actions
These are extra actions a crew member can take when they roll initiative separately from the ship.
Creature Cannon Propulsion
For melee characters feeling sidelined in prolonged, ranged naval conflicts, this rule offers another tool for more dynamic combat.
When a ship is equipped with cannons, they can also launch living creatures. If opting to launch a creature rather than a cannonball, the designated cannon forfeits its attack for that turn. To be propelled, a creature uses 15 feet of its movement to enter the cannon. The cannon’s size dictates the maximum creature size it can accommodate: a Carronade holds Small or tinier creatures, a Cannon can contain Medium or smaller creatures, and a Heavy Cannon holds up to Large creatures. Only Carronades, Cannons, and Heavy Cannons can be used this way. Upon ignition, the creature is thrust in a direction of their choosing, up to the cannon's normal range. Upon landing, an Athletics or Acrobatics check (DC 10) determines the success of the landing. On a failure, the landing creature takes 10 (3d6) bludgeoning damage and gets knocked prone, while a success ensures a safe landing, with the creature landing on its feet.
If a propelled creature collides with a solid vertical obstruction, they must make a Constitution Saving Throw (DC 8 + one per 10 feet traveled). A failed save inflicts 1d6 bludgeoning damage for every 10 feet traveled, up to a maximum of 20d6, while a successful save results in half that amount of damage.
Once a cannon is fired this way, it cannot be used again until the following round.
Rope Acrobatics
For heightened drama during close-quarters ship skirmishes, introduce the thrilling prospect of rope swinging. Successfully swinging requires a free hand and an Athletics or Acrobatics check (DC 10). With a successful roll, a creature can swing a distance equal to twice its Strength or Dexterity score (select one), in any direction. If they're still aloft post-swing and above a ship's deck and below its upper masts, they can clutch another rope as a free action, letting them hang mid-air until their next turn or use their movement to ascend or descend normally. Creatures can still take actions and attack normally while holding onto a rope this way.
A creature can also make a melee attack mid-swing if another hostile creature is within its range during the swing. On a hit, the attack gains a bonus +1d4 to its damage roll. A creature can only make a swinging attack this way once per turn.
Naval Technique Casting
Casting techniques has always been an integral force in shaping the tides of battle, and its presence can be felt even stronger when utilized in naval combat. Creatures aboard ships have the unique opportunity to bend the raw power of their techniques in conjunction with the brute force of maritime warfare. By using a technique on a ship's cannons or components, a creature can choose one of the following effects based on the spell and affected component:
Spell-Infused Cannons
Creatures can meld their power with artillery. Before a cannon or weapon component is fired, a creature can channel a stored technique into the cannonball as an action, so long as the technique's casting time is 1 action. When this infused cannonball impacts its target, the stored technique is released at the point of impact. For example, a cannonball infused with the Maddening Words technique might madden a hit crew member upon detonation. A cannonball infused with the Ice Storm technique can release the technique's effect centered at its point of impact. The creature must expend energy when infusing the cannonball as an action, and the released technique affects an area equivalent to its normal range or a 10-foot radius, whichever is smaller. This allows a technique to damage a ship’s hull points.
Protective Barriers
Abjuration techniques can offer valuable protection to a vessel and its crew. Creatures can extend techniques like Bracing Posture and Slippery Dodge to envelop parts of their ship, so long as they are standing on the ship and are within 5 feet of the component they are trying to protect. This mystical barrier can deflect projectiles or mitigate the impact of spells aimed at the ship. The larger the area covered, the higher the spell slot required. Covering a Medium-sized ship with a spell requires a blues technique or higher, covering a Large ship requires a paradise technique or higher, covering a Huge ship requires an ocean floor or higher, and covering a Gargantuan ship requires a new world technique or higher. The protection lasts for the duration of the spell.
Wind Magic
Channeling air-based techniques (such as from a Warding Wind technique) into the sails can allow the ship to maneuver with unmatched grace. For the duration, the ship can turn on a dime, gains 15 feet of movement during its turn, and gains advantage on checks related to ship maneuverability. Alternatively, using this on an enemy ship offensively will allow you to slow its speed and reduce its maneuverability. If you do so against its sails, for the duration, the ship can't turn, it loses 15 feet of movement during its turn, and has disadvantage on checks related to ship maneuverability.
Crashing
If a ship collides with the space of another creature or object, it might crash. A ship does not crash if the creature or object is at least two sizes smaller than it.
When a ship crashes, the ship’s controller must immediately make a DC 10 Water Vehicles check. On a failed save, it takes damage to the hull based on the size of the creature or object it crashed into, as shown on the Crash Damage table. It also stops moving if the object or creature is bigger than it or one size smaller. Otherwise the ship continues moving and the creature or object moves to the nearest unoccupied space that is not in the ship's path. At the DM's discretion, an object that is forced to move but is fixed in place is instead destroyed.
Crash Damage
Size Bludgeoning Damage
Small 1d6
Medium 1d10
Large 4d10
Huge 8d10
Gargantuan 16d10
A creature struck must make a Dexterity saving throw with a DC equal to 10 + the ship's Strength modifier, taking damage based on the ship's size (as shown on the Crash Damage table) on a failed save, or half as much damage on a successful one.
Hull Points
The hull points of a ship work similarly to player hit points, but they can only be damaged by ship weapons. Ships are immune to all conditions, poison damage, and psychic damage, and automatically fail all saving throws when hit by a spell imbued ship projectile.
Some ships have a Damage Threshold (DT). Any amount of damage dealt below the Damage Threshold is ignored. This is not damage reduction, as any attack that deals more than the Damage Threshold in damage goes through in full.
When a ship’s hull points are reduced to its Critical Threshold (CT) or below, the ship immediately stops moving and its hull points must be restored to above the Critical Threshold before it can move again
If a ship is reduced to 0 hull points, it sinks. Any crew member that does not have the ability to fly, breathe in water, or walk on water must make a DC 30 Strength (Athletics) check to swim to the closest island. Devil fruit users do not make this check and instead immediately start sinking. A crew member that can fly, breathe in water, or walk on water can rescue one other crew member.