A pirate ship can be as much of a character as the scoundrels crewing it, and once the PCs get their own ship, it will likely see as much action as do the PCs themselves. Whether the PCs are fighting rival pirates in hand-to-hand combat on the deck of a sailing rig, attacking a merchantman with a hold full of riches to plunder with their own pirate ship, or sending an entire fleet of ships against an enemy armada, naval combat plays a significant role throughout the Skull & Shackles Adventure Path. Generally speaking, naval combat is handled in one of three ways: shipboard combat (normal combat on board a ship), ship-to-ship combat (combat between two or more individual ships), and mass naval combat (combat between two or more fleets of multiple ships). The rules for these three types of naval combat are detailed in the following section.
Shipboard combat is just like any other combat between the PCs and their opponents, except the encounter takes place on board a ship, rather than in a dungeon or on a forest path. For the most part, shipboard combat can be resolved normally. The only constraints are the size of the ship (and therefore, the size of the battlefield), the danger of falling overboard into the water, and the effects of weather on the ship.
If the combat happens during a storm or in rough seas, treat the ship's deck as difficult terrain. Remember to take into account the effects on spellcasters' concentration checks due to weather or the motion of the ship's deck. If a combatant falls overboard, see the rules for aquatic terrain and water dangers. In all other ways, shipboard combat functions no differently than combat on land.
When ships themselves become a part of a battle, combat becomes unusual. The following rules are not meant to accurately simulate all of the complexities of ship-to-ship combat; rather, they represent an attempt to strike a balance between verisimilitude and ease and speed of play during combat, and can be applied to a vessel of any size, from a simple dinghy to a multi-deck man-o'-war. These rules are a modified version of the vehicles rules found in Pathfinder RPG Ultimate Combat, focusing only on piloting and fighting with a ship on the water. Alternatively, if you'd prefer a quicker and easier way of resolving ship-to-ship combat, you can instead use the fast-play ship combat rules found in the GameMastery Guide. It is important to note that while ships can be attacked in combat, it is difficult to significantly damage such large vehicles. In addition, a captured ship is usually worth more as a prize to be towed or sailed home than sunk to the bottom of the sea. As a result, most ship-to-ship combat ends when the crew of one ship boards another to fight the enemy crew in hand-to-hand combat (see Boarding and Grappling).
The following overview presents the basic rules for ship-to-ship combat in the Skull & Shackles Adventure Path. All ships use these rules for movement and combat.
A ship requires two things to keep it moving—a pilot and a means of propulsion. A pilot is a creature with an Intelligence score of 3 or higher who is physically able to use the ship's control device. A ship's captain is often (but not always) the pilot. The pilot uses the control device and either her sailing skill (see Sailing Checks) or her Wisdom to control the ship. Without a pilot, a ship will not move or will continue moving in a straight line, depending on the ship's state when it becomes pilotless.
Most ships require a crew. A ship without a full crew complement, but with at least half its crew, takes a –10 penalty on all sailing checks. A ship needs at least half its crew complement in order to be piloted at all. If more than half of a ship's crew is killed, dazed, stunned, or rendered unconscious, the ship can only take the “uncontrolled” action. Crew members can take no action while the ship is in motion except to aid in that ship's movement. Any crew required to operate siege engines are in addition to those crew needed to operate the ship.
Ships have sizes and spaces different from creature sizes and spaces. In order to play out ship-to-ship combat on a Flip-Mat or battle mat, a single square on the map corresponds to 30 feet of distance, rather than 5 feet. Most ships are long and thin; rather than taking up a space of an equal number of squares per side like creatures do, a ship's width is always considered to be one square.
Ships do not move like creatures, even when they use creatures for propulsion. They tend to move in the direction of their forward facing, and do so quickly.
Facing: Unlike creatures, ships have a forward facing. Usually one of the shorter sides of a ship serves as the ship's forward facing. Facing represents the effect of inertia on vehicles. Ships move best when moving in the direction of their forward facing, and it takes time and skill to move them in other directions. When piloted correctly, ships can move straight ahead, diagonally, or a mix of both within the same movement. Skilled pilots can make a ship zigzag in a forward direction with ease.
Movement: Ships have a maximum speed and an acceleration listing. The maximum speed is the fastest rate the ship can travel per round (though a wind-propelled ship sailing in the direction of the wind can double this speed). A ship cannot usually start at its maximum speed. Each round, the pilot can attempt to accelerate the ship or decelerate it by a rate equal to its acceleration (see the Movement section in Ships in Combat). The rate at which a ship is currently moving is called its current speed.
Edge of the Map: When playing out ship-to-ship combat on a Flip-Mat or battle mat, the edge of the map forms an artificial boundary—on the open sea, there is no edge of the map. As a result, if a ship moves off the edge of the map, you should extend the map with a new blank Flip-Mat or battle mat, or reposition the ships so they have room to maneuver.
Waterborne Movement: Travel over long distances across seas or oceans uses waterborne movement, measured in miles per hour or day. For muscle-propelled ships, a day represents 10 hours of rowing. For a wind-propelled sailing ship, it represents 24 hours. Waterborne speeds for the most common ship types can be found under Vessels and Vessel Customization.
To control a ship in combat, a pilot must make a sailing check to determine the maneuverability and speed of the ship that round. The ship's propulsion determines what skill is used for the sailing check (see Propulsion and Sailing Skills). If a ship is using two means of propulsion at the same time, such as wind and muscle, the pilot chooses which skill to use, and takes a –5 penalty on all sailing checks. A pilot can always make a Wisdom check in place of a sailing check. Outside of combat, the base DC for all sailing checks is DC 5. In combat, the base DC for all sailing checks is DC 20. A ship without a full crew complement, but with at least half its crew, takes a –10 penalty on all sailing checks.
Aid Another: Just as with other skills, a character can spend a standard action to use the aid another action. This represents an extra pair of eyes observing the enemy, giving orders to the crew, or simply helpful advice. The helping character makes a sailing check as well. If the result is 10 or higher, the pilot gains a +2 bonus on her sailing check. Only one character can use the aid another action to help a pilot on a single sailing check.
Controlling a Ship Outside of Combat: Since piloting a ship outside of combat is easily accomplished by taking 10 on the skill check, sailing checks are not normally needed. Almost every character can do it with relative ease; the DCs are given only to adjudicate special situations that may come up in your game.
Controlling a Ship without the Proper Skill: If a pilot lacks the proper skill to control a ship, the pilot can always make a Wisdom ability check instead of the appropriate sailing check. A pilot can even take 10 (when outside of combat) or gain the benefits of the aid another action when using Wisdom instead of the ship's normal sailing skill.
Every vehicle has a control device for steering. A control device is typically an object with object immunities and resistances and with its own statistics. The following are some of the typical control devices for ships, plus their usual Armor Class, hit points, and hardness. When a control device gains the broken condition, all sailing checks take a –10 penalty. When a control device is destroyed, a ship cannot be piloted until the control device is repaired.
* Oars gain the broken condition if at least half the oars on a ship are destroyed.
Every vehicle has a means of propulsion. Boats and ships are propelled by currents, muscle, wind, or all three forces. The method of propulsion typically affects the speed and maneuverability of a ship, but more importantly, determines the required skill needed to control the ship. Controlling a ship takes common sense, awareness, intuition, and often some amount of skill in the ship's means of propulsion. In the case of wind or current propulsion, it is about using the current and tools like sails, oars, or a rudder to move the ship. In the case of muscle propulsion, it is about guiding creatures to move the ship. The following are the general methods of ship propulsion, along with the skills typically needed to pilot ships propelled by the specified means.
Current: All boats and ships can use water currents for propulsion, but ships that only rely on currents for propulsion are somewhat limited. These vehicles can only move in the direction and at the speed of a current unless they also employ some other means of propulsion or manipulation, and thus often have an additional form of propulsion, such as muscle in the case of a rowboat, or wind in the case of a sailing ship. A current-propelled ship requires a Profession (sailor) check for the sailing check.
A current-propelled ship's maximum speed depends on the speed of the current (often as high as 120 feet). The acceleration of a current-propelled ship is 30 feet.
Muscle: Muscle-propelled ships use oars and rowers to push the ship forward. Sailing skills for muscle-propelled ships tend to be Diplomacy, Intimidate, or Handle Animal, depending on the intelligence and attitude of the creatures supplying the muscle for the propulsion.
For intelligent creatures, use Diplomacy if the creatures providing the propulsion have an attitude of indifferent, friendly, or helpful. If the creatures providing the propulsion are friendly or helpful, Diplomacy sailing checks are made with a +5 bonus. An average crew is considered indifferent, though a particularly loyal crew might be considered friendly. Intimidate is used for intelligent creatures with an attitude of unfriendly or hostile, such as captive rowers on a slave galley. Handle Animal is used if the creatures providing the propulsion are not intelligent.
The maximum speed and acceleration of a muscle-propelled ship depends on the number of creatures providing the propulsion, but most muscle-propelled ship have a maximum speed of 30 feet and an acceleration of 30 feet. Larger muscle-propelled ships with many rowers have a maximum speed of 60 feet and an acceleration of 30 feet.
Oars: All muscle-propelled ships require the use of oars. Oars have their own statistics.
Wind: Wind-propelled ships use sails to harness the power of the wind for propulsion. A wind-propelled ship requires a Profession (sailor) check for the sailing check.
Small wind-propelled ships can move at a maximum speed of 30 feet. Larger ships that are also muscle-propelled often have a maximum speed of 60 feet when using only wind propulsion. Large ships with multiple masts and many sails can have maximum speeds of up to 90 feet. The acceleration of a wind-propelled ship is 30 feet.
All wind-propelled ships can move twice their normal maximum speed when moving in the direction of the wind. A ship using wind propulsion cannot move in the opposite direction from the wind.
Sails and Rigging: All wind-propelled ships require the use of sails and rigging. To move at full speed, a ship requires 10 5-foot squares of sails per mast per square of the ship. For example, a 3-square ship with three masts requires 90 squares of sails. Sails have their own statistics.
Mixed Means of Propulsion: Some ships use multiple forms of propulsion. Multiple methods of propulsion add flexibility and can work in concert to create faster movement. If a ship has two means of propulsion, such as wind and muscle, it generally adds its two maximum speeds together to determine its maximum speed. Acceleration remains the same. Nothing is added for a third form of propulsion, except for the flexibility of having a back-up form of propulsion. A ship with multiple methods of propulsion often requires a large crew to get it going and keep it moving.
On the wide, open sea, one ship can spot another from miles away, making it virtually impossible to surprise another ship. If both ships want to engage in combat, the ships close with one another and begin ship-to-ship combat normally. If one ship wants to avoid combat, however, a chase ensues. At the GM's discretion, a faster ship can always catch a slower ship, but even slow ships can take advantage of favorable winds, currents, or coastal terrain to make good their escape.
When two ships first encounter one another, the pilots of the two ships must make three opposed sailing checks. Whichever pilot wins at least two out of three of the opposed checks is victorious. If the pursuing ship wins, it catches up to the fleeing ship and ship-to-ship combat begins. If the fleeing ship wins, it escapes. If the result is a tie, the pilots should begin a new series of three opposed checks.
The following are some of the various means of propulsion for ships, plus their base Armor Class, hit points, and hardness. To calculate the actual AC of a ship's propulsion, add the current pilot's sailing skill modifier (or Wisdom modifier, if she is using that ability to drive the ship) to the base AC. When a means of propulsion gains the broken condition, the ship's maximum speed is halved, and the ship can no longer gain the upper hand until the propulsion is repaired or replaced. If the ship is in motion, and is traveling faster than its new maximum speed, it automatically decelerates to its new maximum speed.
Oars: Oars are often weaker than the vessels they propel, and are difficult to replace. Destroying a ship's oars is a good way to capture a vessel. Oars gain the broken condition if at least half the oars on a ship are destroyed. If all of a ship's oars are destroyed, the ship can no longer use muscle propulsion and must rely on current and/or wind propulsion only.
Sails and Rigging: Sails (including the rigging that controls them) are often weaker than the vessels they propel, though they are relatively easy to repair. Destroying a ship's sails is a good way to capture a vessel. Sails take double the normal damage from acid and fire attacks (multiply the damage roll by 2). Sails gain the broken condition if at least half the squares of sails on a ship are destroyed. If all of a ship's sails are destroyed, the ship can no longer use wind propulsion and must rely on current or muscle propulsion only.
* More information on magically treated means of propulsion can be found in the Ship Modifications section. Such chases can take days, as one ship struggles to outmaneuver the other. At the GM's discretion, roll 1d4 to determine the number of days a chase lasts.
Withdrawing: Once in ship-to-ship combat, a ship can withdraw from combat by simply moving off the edge of the battle mat, ending ship-to-ship combat immediately. At the GM's discretion, the ship has either escaped completely, or the two ships can go back to the evasion and pursuit rules above.
The following are the rules for how ships act in the combat round.
Once at least two ships are ready to engage in combat, use a large, blank battle mat to represent the waters on which the battle occurs. The reverse side of GameMastery Flip-Mat: Ship contains a blank water grid that is ideal for use with ship-to-ship combat. A single square corresponds to 30 feet of distance (see Size and Space).
Determine which ship is the attacker and which is the defender. As pirates, the PCs will usually be the attacking ship, and their opponent will usually be the defending ship (though the tables might be turned in specific encounters). Represent each ship by using markers that take up the appropriate number of squares, or use the counters provided on page 29 of the Skull & Shackles Player's Guide.
To establish the position of the ships on the battle mat, roll 1d4 to determine the ships' heading (the direction they are facing). Since both ships are coming out of a chase, they are both assumed to have the same heading. A roll of 1 is north, 2 is east, 3 is south, and 4 is west. Place the defending ship as close to the center of the map as possible on the correct heading.
Next, roll 1d8 to determine the bearing of the attacking ship (its position relative to the other ship). Follow the guidelines for missed splash weapons, with a roll of 1 indicating north, and counting squares clockwise for a roll of 2 through 8 to determine the bearing. In some cases, this will put the attacking ship ahead of the defending ship—this simply means the attacking ship overshot its quarry as the chase came to a close.
Finally, roll 1d4+2 to determine the number of squares on the battle mat between the two ships. Place the attacking ship on the map at the appropriate bearing and distance from the opposing ship. Unless otherwise detailed in an encounter, assume that each ship begins combat with a speed of 30 feet. Any siege engines carried on a ship are likewise assumed to be loaded at the beginning of combat.
Wind: If any of the ships in the battle rely on sails and wind to move, randomly determine what direction the wind is blowing by rolling 1d4 and using the same guidelines for determining heading.
When combat begins, the pilot of a ship should roll initiative as normal—the ship moves at the start of its pilot's turn. If a ship has no pilot, it moves on the turn of the last creature that was its pilot, or on a turn determined by the GM. If they wish to take actions in combat, the PCs (and important NPCs involved in the combat) should roll initiative at this time as well.
At the beginning of every round, each pilot makes an opposed sailing check to determine who has the upper hand that round. This represents the vagaries of luck, skill, and the environment, whether catching a favorable gust of wind, taking advantage of a fast current, sliding down the back of a large wave, or disrupting an opposing ship's wind with your own ship's “dirty air.” The pilot who succeeds at the check gains the upper hand, and can immediately reposition her ship by one square in any direction as a free action. For every 5 by which the successful pilot's check exceeds the opposing pilot's check, the pilot with the upper hand can reposition her ship by an additional square. On a tie, neither pilot gains the upper hand.
Alternatively, the pilot who wins the upper hand can change the heading of her ship by 90 degrees. For every 5 by which the successful pilot's check exceeds the opposing pilot's check, the pilot with the upper hand can change the heading of her ship by an additional 90 degrees.
A ship that is upwind of another ship (closer to the direction of the wind) is said to “hold the weather gage,” and gains a +2 bonus on the opposed check to gain the upper hand.
At the start of a pilot's turn, she can take any of the following sailing actions (except the “uncontrolled” action) by making a sailing check to control the ship. The pilot must take whatever action is required before doing anything else that turn. Just as in normal combat, a pilot can perform a standard action and a move action each round. Once the pilot has selected an action, or takes some other action forcing the ship to become uncontrolled, the ship moves. If a ship has less than half its crew or has no pilot, or if the pilot takes no action, takes some other action instead of piloting the ship, or delays or readies an action, the ship takes the “uncontrolled” action.
Full Ahead (standard action): With a successful sailing check, the ship's current speed increases by its acceleration (usually 30 feet), but no higher than its maximum speed. The ship can move forward or forward diagonally. In other words, each time a ship enters a new 30-foot square, it can choose any of its forward-facing squares—the one directly in front or either of the squares directly forward and diagonal. This allows the ship to swerve. A pilot who fails her sailing check does not accelerate and can only move into a square directly in front of the ship's forward facing.
Hard to Port or Hard to Starboard (standard action): The pilot can turn the ship while it moves forward at its current speed. With a successful sailing check, the pilot can change the ship's forward facing either left (port) or right (starboard) by 90 degrees at any point during the ship's movement. Do this by pivoting the ship so that the rear square of the ship takes the place of the ship's former forward facing square. If a ship's current speed is twice its acceleration, the pilot takes a –5 penalty on the sailing check. If a ship's current speed is three times its acceleration, the pilot takes a –10 penalty on the sailing check. If its current speed is four or more times its acceleration, the pilot takes a –20 penalty. On a failed check, the ship does not turn, but can be moved forward diagonally during its movement. Note: A wind-propelled ship that turns into the wind (its forward facing is pointed in the opposite direction from the wind) is said to be “in irons” and takes the uncontrolled action until its pilot turns it to face another direction.
Heave To (standard action): With a successful sailing check, the ship's current speed decreases by 30 feet. On a failed check, the ship does not decelerate. Either way, the ship can move forward on its current facing and can move forward diagonally. If deceleration reduces a ship's speed to 0, some amount of inertia will continue to move the ship forward. The ship moves forward (either directly forward or forward diagonally) 1d4×30 feet before coming to a complete stop. Having the Expert Driver feat reduces this distance by 30 feet (minimum 0 feet).
Make Way (standard action): With a successful sailing check, a pilot can make a tricky or difficult maneuver that forces an enemy pilot to react. The result of this sailing check then becomes the DC of the enemy pilot's next sailing check. On a failed check, the ship's speed remains constant, but the ship cannot move forward diagonally, and the enemy pilot makes his next sailing check at the normal DC.
Stay the Course (move action): With a successful sailing check, the pilot can move the ship forward on its current facing at its current speed, and it can move directly forward or forward diagonally. Failing the check keeps the speed constant, but the ship can only move directly forward, not forward diagonally.
Full Astern (full-round action): With a successful sailing check, the pilot can move the ship backward at a speed of 30 feet, moving either directly backward (the reverse of its forward facing) or backward diagonally. On a failed check, it does not move backward. A ship may only be moved in reverse if its current speed is 0.
Uncontrolled (no action): When the pilot does nothing, if there is no pilot, or if the ship has less than half its crew, the ship is uncontrolled. An uncontrolled ship does nothing except take the uncontrolled action until it stops or someone becomes its new pilot. An uncontrolled ship moves forward only (it cannot move forward diagonally) and automatically decelerates by 30 feet. Even if a ship does nothing, it can still perform ramming maneuvers (see Ramming).
Ships typically don't have attacks and do not threaten any area around them, though some ships can be fitted with rams. Some ships also carry siege engines. Provided that the ship has enough additional crew to operate them, these siege engines can make attacks. While individuals aboard a ship generally don't play a significant role in ship-to-ship combat, important characters such as PCs might still become involved if they wish to fire siege engines or if an enemy ship is in range of their ranged attacks or spells. When attacking a ship, you can attack the ship's structure, occupants, propulsion, or control device. You can also attempt to grapple and board a ship. In addition, a ship can make a ramming maneuver or shearing maneuver as part of its movement.
Attacking the Structure: This is an attack against the ship itself. If the attack is successful, the ship takes damage normally.
Attacking an Occupant: This is a normal attack against a ship's occupant—any creature that is a passenger, pilot, crew, or providing propulsion on a ship. Occupants get partial cover (+2 to AC and +1 on Reflex saving throws) or greater against attacks coming from outside of the ship. Occupants in a forecastle or sterncastle have cover (+4 to AC and +2 on Reflex saving throws), while those inside a port or hatch have improved cover (+8 to AC and +4 on Reflex saving throws). In general, once combat begins among the occupants of two ships (such as when boarding), ship-to-ship combat should be replaced with shipboard combat.
Attacking Propulsion: A ship's means of propulsion usually has its own set of statistics, while creatures propelling a ship use their own statistics. See Attacking an Occupant above if crew members providing propulsion are attacked. Individual ship stat blocks detail their means of propulsion.
Attacking the Control Device: A ship's control device is an object with its own statistics. When a control device is destroyed, the ship can no longer be piloted.
Attacking a Siege Engine: Siege engines mounted on a ship have their own statistics. Siege engines benefit from cover as occupants on a ship.
Broadsides: Some ships can carry a large number of siege engines. Rather than bog down ship-to-ship combat with numerous individual attack rolls, siege engines can be fired in “broadsides.” All siege engines of the same type on a single side of the ship can fire at once. Broadside attacks can only be used to attack the structure of a ship or propulsion. Make a single attack roll for all of the siege engines in the broadside. If the attack roll is successful, all of the weapons hit their target. If the attack roll fails, all of the weapons miss. On a successful attack roll, take the average damage of a single weapon and multiply it by the number of weapons in the broadside to determine the total damage dealt.
For example, a sailing ship with a bank of 10 light ballistae on its port side fires a broadside attack. A single light ballista deals 3d8 points of damage, for an average of 13.5 points of damage. If the attack hits, the broadside deals 13.5 × 10, or 135 points of damage.
When the crew of one ship wishes to board an enemy ship and attack its crew, they must first grapple the other ship. To grapple, the two ships must be within 30 feet of one another (in other words, they must be in adjacent squares on the battle mat). If both pilots want to grapple, grappling is automatically successful. The two crews throw out grappling lines and draw the ships together. If both ships are reduced to a speed of 0 as the result of a ramming maneuver, they are also considered grappled.
If only one pilot wants to grapple, she must make a combat maneuver check against the target ship's CMD, using the base CMB of the ship plus the pilot's sailing skill modifier (or Wisdom skill modifier if she is using that ability to control the ship) as the total CMB of the grappling maneuver. If the check is successful, the target ship is grappled. On the next round, the two ships are moved adjacent to one another, and the speed of both ships is reduced to 0. If a ship has less than its full crew complement, the pilot takes a –10 penalty on her combat maneuver check to make a grappling maneuver.
Breaking a Grapple: The pilot of a grappled ship can attempt to break the grapple by making a combat maneuver check against the opposing ship's CMD, but at a –4 penalty. If the check is successful, the crew has cut the grappling lines and the freed ship may now move as normal.
Boarding: Once two ships are grappled, a crew can board the other ship. The pilot with the highest initiative can choose whether to board the opposing ship with her crew first or wait for the opposing crew to board her ship. Characters boarding an opposing ship are considered flat-footed for the first round of shipboard combat, due to the difficulty of climbing over the ships' rails and finding footing on the enemy deck. Characters using a corvus to board another ship are not considered flat-footed.
To ram a target, a ship must move at least 30 feet and end with its forward square in a square adjacent to the target. The ship's pilot must make a ramming combat maneuver check against the target's CMD, using the base CMB of the ship plus the pilot's sailing skill modifier (or Wisdom skill modifier if she is using that ability to control the ship) as the total CMB of the ramming maneuver. If the check is successful, the ship hits its target, dealing its ramming damage to the target. The ramming ship takes half that damage. A ship's base ramming damage is listed in its stat block. If the pilot's combat maneuver check exceeds the target's CMD by 5 or more, the target takes twice the ship’s ramming damage. If the combat maneuver check exceeds the target’s CMD by 10 or more, the target takes twice the ship’s ramming damage and the target’s speed is immediately reduced to 0. Regardless of the result of the combat maneuver check, the ramming ship’s speed is reduced to 0.
If a ship collides with another ship or a solid object (an immobile structure with a hardness of 5 or more), it also makes a ramming maneuver, regardless of the pilot’s intent. There is no combat maneuver check for this ramming maneuver; its effects happen automatically. When a ship makes a ramming maneuver against a solid object, to determine how much damage both the solid object and the ship take, allow the ship to enter the solid object’s space. The ship will only travel through that space if the damage is enough to destroy the solid object; in all other cases, the ship takes the damage and its speed is immediately reduced to 0 as it comes to a sudden stop directly in front of the solid object.
A ship can be outfitted with a ram on its forward facing. A ship equipped with a ram deals an additional 2d8 points
If a ship has less than its full crew complement, but has at least half its crew, the pilot takes a –10 penalty on her combat maneuver check to make a ramming maneuver. A ship without at least half its crew complement cannot make a ramming maneuver.
Ship-to-ship combat assumes that the PCs are more interested in capturing enemy ships than in sinking them. After all, if you sink a ship, you can't plunder its cargo, ransom its crew and passengers, and sell (or use) the ship yourself. So once a ship has been boarded, ship-to-ship combat ends and shipboard combat begins on whichever ship was boarded first.
Shipboard combat is normally a battle between the “primaries” of the two ships—usually meaning that the PCs fight the enemy ship's captain and any other major NPCs on the enemy ship in normal combat. Meanwhile, the two ships' crews are assumed to be fighting each other in the background.
Whoever wins the “primary” combat (either the PCs or the enemy NPCs) wins the entire battle. In other words, a ship’s crew is victorious over an enemy crew if their captain defeats the enemy captain. While a ship’s crew will likely take losses in a battle, it is assumed that enough members of the defeated crew join the victorious crew to replenish any losses. This keeps the PCs from having to play out combat between large numbers of low-level opponents, and from needing to track exactly how many casualties their crew takes in each battle.
The PCs earn normal XP for the foes they defeat in shipboard combat. In most circumstances, the ship-to-ship battle just serves as a prelude to the main combat. If, however, the PCs decided to fight out an entire ship-to-ship battle and they sink or destroy a ship without ever fighting the ship’s captain and NPCs, then they earn XP based on the captain’s CR (as the captain is the only one piloting the enemy ship in ship-to-ship combat).
A ship may attempt to shear off the oars of an opposing ship, if the target ship uses oars for muscle propulsion. To attempt a shearing maneuver, a ship must be adjacent to the target's forward or rear square and move along the side of the target for a number of adjacent squares equal to the target ship's number of squares. The ship's pilot must make a shearing combat maneuver check against the target's CMD, using the base CMB of the ship plus the pilot's sailing skill modifier (or Wisdom skill modifier if she is using that ability to control the ship) as the total CMB of the shearing maneuver. If the check is successful, the ship shears the target's oars. The target's oars take damage that reduces their hit points to half their maximum hit point total and gain the broken condition, thus reducing the ship's maximum speed by half and preventing its pilot from gaining the upper hand. If the target ship is in motion, and is traveling faster than its new maximum speed, it automatically decelerates to its new maximum speed. A ship that does not use oars for muscle propulsion is unaffected by a shearing maneuver.
If a ship has less than its full crew complement, but has at least half its crew, the pilot takes a –10 penalty on her combat maneuver check to make a shearing maneuver. A ship without at least half its crew complement cannot make a shearing maneuver.
If a ship has no pilot, another creature can take control of the ship as long as the creature is adjacent to the ship's control device and makes a sailing check as a free action. The ship's pilot can always give over control to another adjacent creature as a free action. If a creature wants to take control of a ship from another forcefully, it must kill the pilot or otherwise remove the pilot from the control device. When a new creature becomes the pilot, the ship moves on the new pilot's turn, but not on the new pilot's first turn after taking control of the ship.
Ships have hit points and hardness based on their primary components. Most ships are made of wood (15 hit points per 5-foot-square, hardness 5). When a ship is reduced to below half its hit points, it gains the broken condition. When it reaches 0 hit points, it gains the sinking condition.
Broken Condition: Ships—and sometimes their means of propulsion—are objects, and like any other object, when they take damage in excess of half their hit points, they gain the broken condition. When a ship gains the broken condition, it takes a –2 penalty to AC, on sailing checks, saving throws, and on combat maneuver checks. If a ship or its means of propulsion becomes broken, the ship's maximum speed is halved and the ship can no longer gain the upper hand until repaired. If the ship is in motion and traveling faster than its new maximum speed, it automatically decelerates to its new maximum speed.
Sinking Condition: A ship that is reduced to 0 or fewer hit points gains the sinking condition. A sinking ship cannot move or attack, and it sinks completely 10 rounds after it gains the sinking condition. Each additional hit on a sinking ship that deals more than 25 points of damage reduces the remaining time for it to sink by 1 round. A ship that sinks completely drops to the bottom of the body of water and is considered destroyed. A destroyed ship cannot be repaired—it is so significantly damaged it cannot even be used for scrap material. Magic (such as make whole) can repair a sinking ship if the ship's hit points are raised above 0, at which point the ship loses the sinking condition. Generally, nonmagical repairs take too long to save a ship from sinking once it begins to go down.
The fastest and easiest way to repair a ship is with spells. Mending is not powerful enough to meaningfully affect an object as large as a ship, but make whole affects a ship as if it were a construct, repairing 1d6 points of damage per level. In addition, more mundane methods can also be used to repair ships. Because of their specialized construction, ships (as well as oars and sails) usually require the Craft (ships) skill to repair. Depending on the nature of the damage, skills such as Craft (carpentry) or Craft (sails), or even various Profession skills, can be used to repair ships with the GM's approval. In general, a day's worth of work by a single person using the appropriate skill to repair a ship requires 10 gp of raw materials and a DC 10 skill check, and repairs 10 points of damage on a success, or 5 hit points on a failure. Fabricate can also be used to create the raw material needed for repairs. New oars can be purchased for 2 gp each.
Fire is an ever-present danger on every wooden ship, but while most ships are not in danger of going up in flames from a dropped torch or lantern, alchemical or magical fires can be much more dangerous. Note that many instantaneous fire spells do not automatically catch a ship on fire, but those that deal fire damage over multiple rounds have a better chance of causing a fire on board a ship (see Magic).
When a ship takes fire damage (such as from Alchemist's fire, flaming arrows, certain spells, and other effects at the GM's discretion), it must immediately make a Fortitude save (DC 10 + damage dealt) or catch fire. Unless an attack specifically targets a ship's means of propulsion (such as sails), it is assumed that such attacks affect the structure of a ship itself.
Once a ship has caught fire, it automatically takes 2d6 points of fire damage per round (ignoring hardness) as the fire spreads. The ship's crew can attempt to extinguish the flames as a full-round action for the entire crew, allowing the ship to make a Reflex save (DC 15 + the number of rounds the ship has been on fire). A successful saving throw means the fire has been put out. A failed saving throw results in the ship taking the normal 2d6 points of fire damage for the round.
A ship must take the “uncontrolled” action each round that its crew attempts to put out a fire, as they are not sailing the ship at this time.
Those who would like more detailed rules for fires, spreading flames, and fighting fires can use the system presented in the “Catastrophe!” article in Pathfinder Adventure Path #30: The Twice-Damned Prince.
Creatures can attack ships with spells. Ships are objects, so spells that can only target creatures have no effect on ships. However, because a ship is actively crewed and piloted, it can make saving throws against spell effects. Ships are immune to most spells that require a Will save. A ship without a crew is considered an unattended object and cannot make saving throws.
The effects of most spells on ships can be determined normally. However, certain spells have different effects in naval combat. The effects of these spells are detailed on the page Spell Effects in Naval Combat. GMs can use these examples as guidelines for determining how other spells not listed here affect ships. For the most part, these effects only apply during ship-to-ship combat, not during normal combat aboard a ship, though some affects (such as starting fires), could still apply, at the GM's discretion.