Begin a boarding combat with two ships that have a gap of 5 feet or less between each other, since a Leap action or a typical gangplank can cover that distance. Ten feet might also work if the boarding party has grappling hooks or other suitable tools. You can leave the ships static on the game map rather than dealing with any ship movement or piloting. For a fun tweak, you can also use two battle maps next to one another—one for each ship—and move one of them 5 or 10 feet at the end each round to mimic their motion on the sea.

Swinging on rigging or grappling hooks is a classic trope and can be a good way to get combat started. Swinging from one ship to another on a rope typically lets a character swing up to double their Speed with a single action if they succeed at a DC 20 Acrobatics check.

The decks of ships, their rigging, and the motion of the waves can come together to create interesting terrain on the battle grid. Some common terrain effects include the following.

Damaged Decks: Portions of deck that have been damaged by combat or collisions might fall apart when pressure is put on them. When a creature steps on one, they can attempt an Acrobatics checks or Reflex save (typically DC 20) to leap out of the way. If they fall, they can try to Grab an Edge as normal. Falling through usually involves landing belowdecks and needing to reach a ladder or stairs to climb back out.

Flotsam and Jetsam: Debris from a ship or objects thrown overboard can float near a vessel. Characters knocked overboard might use these as platforms to fight from or return to the ship.

Gangplank: Walking the plank requires using the Balance action.

Rigging: Climbing rigging requires a DC 15 Athletics check in most cases. Some rigging features ropes under tension that can let someone move more quickly if they undo or sever a certain knot.

Unstable Decks: The movement of the water or impacts against other ships can shift a deck so it’s harder to traverse. It’s best to use this sparingly, typically no more than every 2 rounds of combat. Declare what the terrain’s effect will be at the start of a round. If the ship is pitched or rolling, decide whether the fore, aft, port, or starboard is elevated. Moving toward that side of the ship is difficult terrain. Extreme movement of the ship on the water can cause the deck of a ship to be uneven ground instead. Since this is a significant drawback and makes combat much more difficult, use uneven ground even less frequently.

Weather: Some of the weather effects described here, which primarily affect sailing combat, could also apply during boarding combat.

Though the focus of boarding combat should be on tactical combat, siege weapons aboard the ships might still come into play. If weapons like ballistae are mounted on the top deck, the crew can use them using the standard siege weapon rules. These weapons can also be disabled as described here.

Ships might attempt to disengage and leave the fight if it’s going badly for their side. The vessel’s pilot can use the Disengage activity to attempt to free the ship. Disengage might not be an option if the ship is securely tethered to another or is otherwise held in place.Disengaging PCs: If the PCs succeed, it’s best to end the encounter and let them escape. If the battle is a climactic encounter in an adventure or campaign, however, you might want to evolve it into sailing combat or a naval chase to keep the drama high.

Disengaging Enemies: Enemies should Disengage only as a last-ditch effort when they’re admitting defeat. If their attempt fails, have them surrender or otherwise accelerate the end of the fight. If the enemies succeed and the PCs truly want to play out the rest of the battle, it’s usually preferable to tweak the details to let the PCs easily catch up and defeat the foes, or to have them narrate how they secure victory. If you expect your players will not accept their foes escaping in defeat, it’s better to have the enemies surrender instead of attempting to Disengage in the first place.

You can simplify initiative to make sailing combat run more smoothly. The easiest option is to place the ships’ pilots at the top of the initiative order, rolling Sailing Lore for initiative but comparing their results only to one another. This ensures that both ships maneuver into position before anyone else on board takes their actions. The two sides of the conflict need to deal with the same circumstances for their attacks, spells, and other actions.

If a player character is piloting the ship, let them decide how to Drive it and roll normally. The Drive action is built to work well when multitasking, so if the pilot has few things to do, the player might be too strongly tempted to take complicated Drive actions. It’s best to make sure the pilot has other options for the remaining 2 actions during their turn, such as casting spells, making ranged attacks, or commanding NPC sailors.

The PCs might want to have an NPC pilot their ship. If an NPC is piloting a ship during a naval battle and the PCs are primarily fighting, it’s best to assume that the ship is staying on course to allow for combat to take center stage rather than have the pilot make tricky maneuvers. Have the NPC pilot Drive with 1 action; assume they succeed rather than rolling. A PC can spend a single action to give specific orders to the NPC, in which case the NPC typically tries to enact those orders the next time they Drive.

Battles in sailing combat should be kept to a close enough distance to allow for a variety of ranged offensives between ships. It’s much harder to get melee attacks in the mix, so if your party is heavily melee-focused, it might be better to skip sailing combat and stick to the other types of naval conflicts. Alternatively, you can make sure they have options to get to the other ship, such as separate rowboats or teleportation.

Some of the attack options include:

• Ranged Weapon Attacks: Creatures can attack with their normal ranged weapons and use any appropriate feats, magic item abilities, and the like.
• Ranged Spells: Spells with a range can also be used normally, and some cones, lines, or emanations might even reach in some situations. You might want to make such spells harder to aim on a moving ship, similarly to the penalties noted in Ranged Attack Challenges.
• Siege Weapon Attacks: The crew can attack using the siege weapons mounted on a ship. This usually takes multiple rounds, the effort of multiple crew members, or both.
• Ramming: One ship can ram another using the Run Over action. This is very dangerous for the pilot and their own vehicle and is a last resort for most captains.

The Vehicles in Combat rules note that attacks made while on a vehicle that has moved within the last round take a –2 penalty, or a –4 penalty if the vehicle is uncontrolled or any action in the last round had the reckless trait.

That section also describes the rules on cover. In sailing combat, creatures on a ship’s top deck don’t get cover against attacks from the other ship’s top deck, though they might be able to find cover behind masts or cargo on the deck. Creatures using hatches on the decks below typically have standard cover and can Take Cover as normal.

If the ships have larger crews, you can easily end up with allied NPC crew members attacking unimportant enemy crew members. To keep the game moving quickly, avoid playing out every single attack roll for these characters. Instead, play these NPC clashes narratively. Thin the numbers as the fight goes on, with the minor characters being defeated or knocked overboard.

If you’re using siege weapons, you can also put NPCs to work Aiming and Loading them. You can place all of the crew who are helping with siege weapons together in initiative so all the maintenance of the siege engines happens at once.

The weather at sea can transform a sailing combat encounter. Including a weather condition is optional! It’s usually best to use only one type of inclement weather and to avoid combining it with other major complications.

Dense Fog or Rain: The normal rules for fog or rain causing concealment matter at fairly large distances. If you want extremely dense fog or rain to affect naval combat, you can create concealment at a much shorter range. Because this adds a further detriment to ranged attacks, dense fog is typically better used in boarding combat.

Winds: Strong Winds have the strongest impact on sailing combat. The default rules should mostly be reserved for flying creatures. Imposing penalties on ranged attacks is less interesting, especially when the penalties for moving vehicles are likely already hurting ranged attack accuracy.

Winds can have a greater and more interesting impact on the movement of ships. At the start of a round, tell the players the direction of any high wind, such as blowing from the northeast, and tell them how many feet it will push all ships at the end of the round (usually 5 or 10). Movement against the wind is difficult terrain, and moving with the wind moves the ship 10 feet (2 squares) each time it would move 5 feet (1 square). At the end of the round, the ships are pushed the amount you stated at the start of the fight. As the new round starts, say whether there are any changes to the wind. Typically, the wind’s direction changes no more than 45º per round, such as going from blowing from the northeast to blowing from the north.

If a ship becomes broken, the fight continues, but if it’s destroyed, the sailing combat is over! The ship will eventually sink, though it takes long enough that you have time for another scene. It might be time to play out a final duel atop the slowly sinking remains!

Crew members can typically swim, surviving the destruction of their ship as long as they get taken aboard another vessel without too much delay or have a large enough piece of flotsam to rest on.

Since it’s a catch-all skill for many different shipboard tasks, the Sailing Lore skill can often be used in place of other skills during a naval chase. If a character is highly skilled in Sailing Lore, this is their time to shine! Allow liberal substitutions if you have a player who’s highly invested in the skill. Nature can be used instead of Sailing Lore for wind-powered vehicles, but only for Sailing Lore tasks related to actually steering the ship, not for other shipboard tasks.

Naval Chase Obstacles

Damaged Sail (1st)	DC 13 Crafting to repair, DC 15 Survival to scavenge materials; Damaged Steering (5th) DC 20 Crafting, DC 22 Survival
Take Advantage of Favorable Winds (1st)	DC 13 Sailing Lore to speed ahead; DC 15 Athletics to adjust the rigging; Powerful Tailwinds (4th) DC 18 Sailing Lore, DC 22 Athletics
Squall (2nd)	DC 14 Nature or Survival to avoid the worst, DC 16 Sailing Lore to cut through the storm; Perfect Storm (8th) DC 22 Nature or Survival, DC 24 Sailing Lore
Athamaru Outpost (3rd)	DC 16 Diplomacy or Society to ask for safe passage, DC 18 Crafting to make goods to trade; Quatoid Colony (8th) DC 22 Diplomacy or Society, DC 24 Crafting
Doldrums (3rd)	DC 16 Medicine to keep the crew healthy, DC 20 Arcana or Nature to use magic for temporary propulsion; Magical Stagnation (7th) DC 21 Medicine, DC 25 Arcana or Nature
Floating Debris (3rd)	DC 16 Survival to scout a safe course, DC 18 Sailing Lore to steer carefully... very carefully; Dangerous Rocks (6th) DC 20 Survival, DC 22 Sailing Lore
Cannon on the Shore (4th)	DC 17 Deception to outfox the attackers, DC 19 Intimidation to cow them with return fire; Fort on the Shore (9th) DC 24 Deception, DC 26 Intimidation
Lurking Sea Monster (6th)	DC 20 Nature to soothe the savage beast, DC 24 Stealth to sail quietly; Lurking Kraken (12th) DC 28 Nature, DC 32 Stealth