If you are one of the two people who reads this blog, you may be aware of my Dungeons and Dragons campaign, the Endless Sea.
Now, The Endless Sea is a naval-based campaign, and as such there needs to be ship-to-ship combat at some point. In this post, I’ll be writing down an untested Naval Combat system for use with 5e.
Three things to note before I begin. 1) This is not a historically accurate system. My primary inspiration is the naval combat in Assassin’s Creed IV: Black Flag. 2) This system may not necessarily require a grid-map, but it makes it much easier. 3) Mechanically, I am taking inspiration from 4e’s Skill Challenge rules.
The Dungeon Master’s Guide lists a number of rules for using ships, and I will happily pilfer from those rules and incorporate them into these ones.
Ship Statistics
Ships possess the following Combat relevant stats: Hit Points (HP), Armor Class (AC), Damage Threshold (DT), and Speed.
HP measures how much damage a ship can take before it sinks. AC represents the target number of an attack roll made against the ship, much as it does for normal creatures. DT represents a target number for damage rolls. For example, if a ship has DT of 15, and it takes 12 damage, then that damage is considered superficial and nothing is subtracted from the HP. However, if it takes 17 damage, then that damage is subtracted from HP as normal.
Speed, when measured for combat purposes, is different from the speed listed in the DMG. In combat, Speed measures how far a ship moves per round. This is called Combat Speed. A round of Naval Combat is roughly 3 minutes.
The following chart converts the DMG’s mph speeds to Combat speeds.
|
mph |
Combat Speed |
|
>4 |
800 ft |
|
4 |
700 feet |
|
3 |
600 ft |
|
2 |
500 ft |
|
1 |
400 ft |
Note that these speeds are not meant to be perfect conversions from miles per hour to feet per 3 minutes. Liberties were taken and adjustments were made in order to make sure combat was more exciting in the scale we will be playing in.
On the grid, a single square represents 100 ft. So if your vessel has a combat speed of 500 ft, it can more 5 squares per round.
Each vessel also has a size, which determines how many squares/feet it takes up. Small ships occupy and control a 100 x 100 foot area (a single square). Medium ships occupy a 200 x 100 foot area (2×1 squares). Large ships occupy a 300 x 200 foot area (3×2 squares).
The Combat Round
Each round of Combat has two turns: Friendly turn and Enemy turn (if there are more than two sides to a battle, then this number increases, as each side has its own turn).
If one side surprises or ambushes the other, then that side takes its turn first. If neither does, then the average Speed of each side determines turn order (the side with the higher average speed goes first).
Navigational Actions
During its turn, a ship is always assumed to move a distance equal to its speed in the direction it is facing. Two actions can be taken to change this. Characters may only take one action per round.
Halting requires no skill checks to perform. When you halt a ship, it stops sailing, and will drift 100 feet in the direction it is facing each turn. You can restart a vessel’s movement by making the same skill checks required for turning (see below).
Turning alters the course of the ship. During your turn, you may turn a ship one point in either direction (a point here refers to one of eight directions; up, down, left, right, and the diagonal directions between each). Two successes on any combination of the following checks are required to turn the ship: Strength (Athletics) and/or Dexterity (Acrobatics). These represent the characters tying off sheets, cutting sails, and commanding the helm.
Note that, if a character has proficiency in vessel (water) as granted by the Sailor background, they may add their proficiency bonus to either Strength or Dexterity for these checks, regardless of whether they have proficiency in the relevant skill. Similarly, a character with proficiency in Nature or Survival may aid a character taking the turning action, granting them Advantage on their role.
The DC of Turning is determined by the size of the vessel. Turning Small vessels is a DC of 11, Medium is a DC of 13, and Large is a DC of 15. If only one success is met during a round, then the vessel is considered to be Turning during the enemy’s turn, and the second success may be met during the next round. If neither success is met, then the ship does not alter course.
Some weapons can cause drift if they hit a ship that is turning. When Drift occurs, the vessel remains in position and is incapable of turning until the end of its next turn.
If two ships collide into one another, and the aggressor does not have a ram, then both vessels take 3d10 damage. If a ship collides with something stationary, such as rocks, it takes 4d10 damage. If a ship collides with a beach, it lands on the beach, becomes stationary until it is pushed off, and takes 2d10 damage.
Nautical Weapons
The following weapons can be installed on ships and used in combat.
An Arcane Ballista is a massive crossbow that channels magical power. It has a range of 400 ft. and deals 3d10 damage on a hit. To make an attack with an Arcane Ballista, a character rolls Intelligence (Arcana) against the target vessel’s AC.
A Cannon is a standard weapon. It has a range of 500 ft. and deals 5d10 damage on a hit. To make an attack with a cannon, the character rolls Strength (vehicle (water)) against the target vessel’s AC. Two successes are required to fire a cannon.
Cannon Groups are groups of cannons that line the side of the vessel. A single character cannot attack with an entire cannon group and so must instead command the crew. To make an attack with a Cannon Group, a character must roll Charisma (Persuade), Charisma (Intimidate), or Charisma (Perform) against the target vessel’s AC. 1d4 is then rolled to determine how many cannons hit the target, and damage is rolled for each. Note that cannon groups can only fire on vessels that are parallel to the vessel they are on, not in front of or behind it. Two successes are required to fire a cannon group.
Rams are located on the bow of a vessel. Ram attacks are made by colliding with another vessel. If the vessel performing the collision has a ram, then it deals 6d10 damage to the target vessel. This can cause Drift.
Swivels are smaller weapons for damaging crew. A swivel has a range of 100 ft. and deals 2d6 damage on a hit. This damage ignores the vessels DT. To make an attack with a swivel, a character must make a Crossbow attack against the target vessel’s AC.
Sinking
When a vessel’s HP drops to 0, it begins to sink. Small vessels will sink in one round, Medium vessels in two, and Large vessels in three.
A friendly vessel may attempt to rescue the crew of a sinking vessel by halting in an area adjacent to it. If rescue does not come, the crew is in the water and must swim to safety.
Boarding Enemy Vessels
When a vessel is adjacent to an enemy vessel, it may attempt to board. A character rolls Intelligence (Nature), Wisdom (Survival) or Dexterity (vehicle (water)) to maneuver their vessel properly next to the other. The DC is the same as the DCs for Turning.
If boarding is successful, then the aggressor crew arrives on the enemy vessel and normal combat rules come into play.
An NPC crew may surrender if the PCs kill the enemy captain, who is usually both easily distinguished and tougher than the rest of the crew.
NPC Ships
Since it would be an unnecessary and ridiculous amount of work to create individual crew members for NPC ships, these vessels function as characters in and of themselves.
These vessels receive flat bonuses to certain actions. Some actions it can only take every two or more rounds. The amount of time a vessel must wait before it can take another action is called recharge.
Here is an example of an NPC vessel statblock:
Small Gunboat
Boat, small
HP 75
AC 13
DT 15
Combat Speed 500 ft.
——
ACTIONS
Turning +6 vs DC 11
Cannon +5 to attack, range 500 ft., damage 5d10. Recharge every two rounds.
And there you have it. My homebrewed Naval Combat rules for Dungeons and Dragons 5th Edition. Keep in mind that these are currently untested and as such I may end up tweaking them after my players have had their first bout of naval combat.
EDIT: Tweaked a few bits where the rules referenced a skill that doesn’t actually exist. For some reason, I thought there was a Navigation skill
Everything Explodes 