OSR: Ship Combat Rules Test

I'm trying to build a set of very simple ship combat rules. They should be mechanically crunchy enough to allow for variation, upgrades, and tense duels, but not so complicated that you need a slide rule and a whole table of terms to use. The rules are vaguely based on FFG's Rogue Trader starship combat rules. They should work for Age of Sail combat... as seen on TV.

The core ideas should also be adaptable to ancient sailing battles. Just adjust the speed and range accordingly.

Feel free to pick these apart. The exact numbers are trivial to adjust based on playesting. General concepts are more difficult.

Jeremy Paillotin

Combat Sailing

As opposed to exploration sailing. This is for fights.

Wind

There are 3 kinds of wind:

1. No wind (doldrums, becalmed). A special event on the weather table.

2. Way too much wind (storms, hurricanes, waterspouts, etc.). Special events on the weather table.

3. A sensible amount of wind.
If there’s a sensible amount of wind it fades into the background. Films generally don’t consider it important. Ships maneuver at great speed into the wind, round corners, and pass in front of each other without too much difficulty.

Rules for fog, whirlpools, hurricanes, rapids, shoals, and islands during combat will be added at some point, but based on these rules I think you can see how I'd do it.

Ship Combat

You’ll need a grid. Each square is 100 feet. Each ship combat turn is 5 minutes. Ship speeds are quite a bit lower than top sailing speed, but it's a sacrifice I'm willing to make to avoid using hundreds of sheets of graph paper.

Each round, ships act in order of size, largest to smallest. In order:
1. The ship attempts a Manoeuvre for the round.
2. The ship moves its full Speed straight ahead.
3. The ship may turn up to 45 degrees.
4. The ship fires its Weapons.
5. The ship performs any Special Actions.

Ship Stats

Speed: How fast the ship can move, in squares per turn. This doesn’t correspond to knots or actual speeds. It’s a convenient abstraction to make combat interesting. Don’t tell the sailing people.

Manoeuvre Bonus: How nimble the ship is. Applies to rolls made for Manoeuvres.

Ship Hit Points: The total health of the ship. Negative effects occur at half and quarter HP.

Masts: Number of masts. Useful for some critical hits and identifying ships at a distance.

Crew: Hit Points of sailors and officers who perform regular sailing tasks and assist with boarding actions.

Marines: Hit Points of specialized combat-only troops who do not assist with regular sailing tasks. Cargo Capacity: How much Loot a ship can carry.

Main Weapon Capacity: Arcs are 45 degrees. Prow weapons only fire forward, Stern weapons only fire backward, Port and Starboard weapons fire left and right. Some esoteric ships carry Turrets capable of firing left, right, or forward, or Spine weapons that can only fire dead ahead.

Examples

Stats are all provisional; testing is ongoing.

Rowboat
Speed: 2
Manoeuvre Bonus: +0
HP: 5
Masts: -
Crew: 1 HP
Marines: -
Cargo Capacity: 1
Main Weapon Capacity: -

Raiding Sloop
Speed: 6
Manoeuvre Bonus: +5
HP: 20
Masts: 1
Crew: 10 HP
Cargo Capacity: 2
Main Weapon Capacity: 1 Pro
Raiding Sloops may automatically use the Quick Turn Manoeuvre each turn, in addition to any other Manoeuvres. It may not use the Hard About Manoeuvre in the same turn.

Costal Cutter
Speed: 5
Manoeuvre Bonus: +5
HP: 30
Masts: 1
Crew: 10 HP
Marines: -
Cargo Capacity: 2
Main Weapon Capacity: 1 Prow
Coastal Cutters may automatically use the More Sail Manoeuvre each turn, in addition to any other Manoeuvres.

Brawling Corvette
Speed: 4
Manoeuvre Bonus: -10
HP: 50
Masts: 1
Crew: 20 HP
Marines: 10 HP
Cargo Capacity: 3
Main Weapon: 1 Port, 1 Starboard

Customs Frigate
Speed: 4
Masts: 3
HP: 100
Crew: 50 HP
Marines: 20 HP
Cargo Capacity: 6
Main Weapon: 2 Port, 2 Starboard

Weapon Stats

Range: In squares. Each square is 100 feet. This is the maximum range of the weapon.
Range 1 means the ships must be adjacent.
Range 0 means the ships must occupy the same square or be Locked Together.

To shoot a weapon, roll under 8+ any bonuses. An extensively trained crew might increase this to 10+bonuses, but most of the time, gunnery is horribly inaccurate at anything beyond point-blank range.

A weapon firing at half range gains a +4 to hit. Any weapon fired at Range 0 gains a +8 to hit. Getting to point blank range is the goal. The role of a ship is to carry its guns within point blank range of an enemy, fire them as many times as possible, and render the enemy unable to return fire. Victory is assured through boarding actions.

On a critical hit, roll on the Critical Hits table.

Damage: Like a standard weapon. On a hit, deal damage to the ship’s HP. All hits also deal 1 damage to a ship’s Crew HP and Marines HP. 

Some weapons have special properties, restrictions, modifiers, etc. listed below their main stats.

Prow or Stern Chasers
Range: 8
Damage: 2d6

Cannon Broadside
Range: 8
Damage: 2d6+3

Carronade Broadside
Range: 2
Damage: 3d6+6

Manoeuvres

The helmsman must roll under their Dexterity + the ship’s Manoeuvre bonus + any bonus or penalty from the manoeuvre attempted.

Quick Turn
Bonus: 0
Pass: After moving half its speed, the ship may turn 45 degrees, then complete its movement. It may not turn at the end of its movement.
Fail: The ship moves and turns normally.
Hard About
Bonus: -4
Pass: After moving half its speed, the ship may turn 45 degrees, then complete its movement. It may then turn 45 degrees at the end of its movement.
Fail: The ship moves and turns normally but takes 1d6 damage from the strain.
Drop Anchor
Bonus: -10
Pass: The ship moves 1 square forward, then immediately turns 45 degrees. It does not move further and may not turn. All shooting is at a -4 penalty this turn. The ship is now At Anchor. It takes 1d6 damage from the strain.
Fail: the ship moves 1 square forward, then immediately turns 45 degrees. It does not move further and may not turn. The ship may not shoot this turn. The ship is now Swamped. It takes 3d6 damage from the strain.

More Sail
Bonus: 0
Pass: The ship may move up to 2 additional squares straight ahead.
Fail: The ship moves normally but may not turn.

Trim Sails
Bonus: 0
Pass: The ship may move up to 2 fewer squares this turn. It must move at least 1 square.
Fail: The ship moves and turns normally.
Line Us Up
Bonus: -4
Pass: The ship’s shooting gains a +4 bonus this turn. The ship may move and turn normally.
Fail: The ship moves normally but may not turn at the end of its movement.
Take Evasive Action
Bonus: -8
Pass: All incoming shooting suffers a -4 Penalty. This penalty does not apply at Point Blank range. The ship moves normally but must turn at the end of its move.
Fail: The ship moves normally but must turn at the end of its move.

Prepare For Boarding
Bonus: -4
Pass: The ship may move up to 2 fewer squares this turn. If the ship ends its move next to an enemy ship, while moving parallel to it, the ship may instead move into the same square as the enemy ship. It is now at Point Blank range and may initiate boarding actions.
Fail: The ship may move up to 2 fewer squares this turn.

Ramming Speed
Bonus: -5
The prow of the ship must be facing the target.
Pass: The ship moves up to its full speed towards the target. If the ship has any weapons that face forward, they may fire with a -8 penalty just before the ships collide. Both ships deal 1d6 damage to each other for each 10 HP they have remaining. They are now Locked Together.
Fail: The ship moves its full speed past the target. If the ship has any weapons that face forward, they may fire with a -8 penalty.

Special Actions

Any PC can attempt a Special Action. Roll under the stat listed with the action, applying the bonus or penalty listed. NPC ships can generally attempt 2 or 3 special actions.

Fire at Will
Roll: Charisma +0
Pass: The ship may fire at any point during its Move, interrupting the usual turn sequence. It may not fire a second time in that turn.
Fail: The ship shoots normally, but with a -8 penalty this turn.Cut Anchor
Roll: Charisma or Strength +0
Pass: The ship is no longer At Anchor. The ship will require a new anchor.
Fail: The ship is still At Anchor.Cut Apart
Can only be used if the ship is Locked Together with another ship.
Roll: Strength or Charisma -4
Pass: The ship is no longer Locked Together. At the start of its next turn it may move normally.
Fail: The ship is still Locked Together.

Man the Pumps
Can only be used if the ship is Swamped.
Roll: Strength or Intelligence -4
Pass: The ship is no longer Swamped. At the start of its next turn it may move normally.
Fail: The ship is still Swamped

Lock Together
Roll: Dexterity or Intelligence -4
Can only be used if the ship is at Point Blank Range with another ship.
Pass: The ships are now Locked Together.
Fail: The ships are not Locked Together.

Boarding Action
Can only be used if the ship is Locked Together with another ship.
Roll: Any Stat – 4
Pass: Deal 1d6 + 1 damage for each 10 HP of Crew + 2 damage for each 10 HP of Marines to the enemy ship’s Crew HP or Marines HP. The enemy inflicts 1 damage for each 10 HP of enemy Crew + 2 damage for each 10 HP of enemy Marines to the boarding ship’s Crew or Marines HP. Damage occurs simultaneously.
Fail: Deal 1 damage for each 10 HP of Crew + 2 damage for each 10 HP of marines to the enemy ship’s Crew HP or Marines HP. The enemy inflicts 1 damage for each 10 HP of enemy Crew + 2 damage for each 10 HP of enemy Marines to the boarding ship’s Crew or Marines HP. Damage occurs simultaneously.

Hasty Repairs
Roll: Any Stat -4
Pass: Heal 1d4 Ship HP or repair 1 damaged weapon or repair a damaged rudder or put out a fire.
Fail: No effect.

Statuses

Locked Together
The ships move straight ahead at the slowest ship’s speed. Both ships can still fire normally. They count as being at Point Blank range with respect to each other.

At Anchor
The ship does not move and cannot make any Manoeuvres. It may turn up to 45 degrees.

Swamped
Instead of moving normally, the ship moves 1 square forward. It may not turn and cannot make any Manoeuvres.

Sinking
A ship will sink in a number of rounds equal to its original HP divided by 10. Find boats, flee, grab treasure, and run around in a panic.

Dismasted
A ship with no masts cannot make any Manoeuvres. If it didn’t start with any masts (Rowboats, Gigs, etc.), this does not apply.

Half Ship HP
A ship at half HP takes a -4 penalty to all Shooting, Manoeuvres, and Special Actions.

Quarter Ship HP
A ship at half HP takes a -8 penalty to all Shooting, Manoeuvres, and Special Actions. It is automatically Swamped.

Zero Ship HP
A ship at Zero HP is Sinking. It cannot Shoot, or take any Maneuver or Special Actions.

Half Crew HP
A crew with half Crew HP takes an -4 penalty to all Shooting, Manoeuvres, and Special Actions.

Zero Crew HP
A ship with Zero Crew HP must surrender. This doesn’t mean everyone is dead, but it does mean further resistance is impossible. Everyone is wounded or exhausted.

There will be some sort of ship character sheet to help track all of this.

Critical Hit Chart

1. Mast Shattered. Remove one mast from the target ship.
2. Holed. The enemy ship is now Swamped.
3. Cannons Damaged. 1 weapon on the facing struck now inflicts 1d6 less damage.
4. Cannons Destroyed. 1 weapon on the facing struck is inoperable until repaired.
5. Rudder Struck. The ship must turn after moving, in the direction it last turned (or a random direction if no turns have been made), until repaired. It may not
6. Deadly Splinters. Inflict an additional 1d6 damage to both Crew HP and Marines HP.
7. On Fire. The ship takes an additional 1d4 damage to Ship HP each turn until the fire is extinguished.
8. Well Struck. The ship takes an additional 1d6 damage to Ship HP.

Example Combat

A Raiding Sloop (Red) has run into a Customs Frigate (Blue). The sloop is enormously outclassed and outgunned. She is also carrying a cargo of opium from Yoon-Suin; very illegal.

1. The Customs Frigate moves first, as she is the larger ship. Her Speed is 4. She is not sure where the Sloop will go, so she attempts no Manoeuvres.

2. The Customs Frigate moves straight ahead 4 squares, then turns 45 degrees to starboard, hoping to catch the Sloop in her powerful broadside. She takes no Special Actions. She could take the Fire At Will Special Action, but she hopes to catch the enemy in a fully organized broadside at the end of her next turn, not sporadic and less damaging fire.
3. If the Sloop moves straight ahead she will be at the Frigate's mercy. The Sloop can automatically perform the Quick Turn Manoeuvre. She chooses to perform this Manoeuvre, and also chooses to try for the Line Us Up Manoeuvre. She succeeds. Her shooting gains a +4 bonus this round.

4. She moves 3 squares ahead, turns 45 degrees, and moves a further 3 squares.

5. The Sloop now has the Frigate directly in her sights. She fires her Prow Chasers. The enemy is at half range (+4 to hit) with a further +4 from the Line Us Up Manoeuvre. Base 8+4+4 = 16. The Sloop rolls, hits, and deals 2d6 damage to the Frigate's Ship HP, plus 1 damage to their Crew HP and Marines HP. This barely chip's the Frigate's paint, but it is still a nasty surprise for her officers and crew.

6. The Frigate, realizing the Sloop may escape her, decides to use the Hard About Manoeuvre. 
7. She moves half her speed (2), turns 45 degrees, moves her remaining distance (2), and then turns a further 45 degrees.
8. From her new position, the Sloop is likely to pass within her full broadside.

9. The Sloop, however, hopes to use her considerable speed to escape. She lays on More Sail and uses her automatic Quick Turn Manoeuvre. She succeeds. She moves 4 squares, turns 45 degrees, and moves another 4 squares.
10. The Frigate can try to come about and catch her, but at extended range and no easy way to add bonuses to shooting, the Frigate is very unlikely to ever catch up with the quick Sloop. The Sloop can also manure directly in front of the Frigate

Design Space

There's lots and lots of room.

It should be reasonably simple to add rules for flamethrowers, chain shot, lightning guns, torpedoes based on the core weapon stats.

Upgrades for extra sails, crocodile-powered waterwheels, fog generators, and all the usual piratical nonsense should be easy enough to add. I don't want to create an explicit "upgrade slot" system because that gets fiddly.