D&D 5E Brainstorming some better naval combat rules

This thread - Piloting/Driving Combat in RPGs is No Fun! - had a core point that a big problem with vehicle combat in RPGs is that usually only one player makes any meaningful choices. There's a fair bit of dice rolling that doesn't really affect the narrative. Since 5E is all about resolving things quickly with rulings instead of rules, I was curious how best to do naval combat in 5E without falling into that same trap.

I know the Ghosts of Saltmarsh adventure has a naval combat section, but it felt too fiddly for D&D 5E's design conceits.

I'm considering two ways to do naval combat in D&D 5E. I am hoping you might offer me some feedback, please.

Option One - Ships as Monsters
Ships use a statblock basically just like a monster. They have HP, attacks, movement, saves. The only real difference is that the scale is one square per 100 feet, and each round is one minute. Medium ships are 1 square (100 feet). Large ships are 2 squares, and Huge ships 3, Gargantuan 4. Your average ship has speed 400 to 600.

The PCs pick a captain who 'controls' the ship and plays it like a monster. They pick an ability score to represent their style of command. Also, their stat bonus determines how many 'officer actions' the ship can benefit from each turn. (So a stoic dwarf captain might pick Constitution. If his Con score is 18, the ship can benefit from 4 actions per turn.)

Str provides a bonus to combat maneuvers and to ship attacks at point blank range.
Dex provides a bonus to ship AC and to checks to avoid difficult terrain.
Con grants the ship temporary HP each turn.
Int makes it easier to score critical hits on opposing ships.
Wis provides a bonus to initiative.
Cha grants a bonus to the ship's saving throws.

Then each PC (up to the limit based on the captain's stat) can take one action per naval round to help the ship. You could make a Vehicle skill check to basically do combat maneuvers (you can drive an enemy ship into bad terrain, or ram to capsize, or grapple for a boarding action). Concealment might be hard to get, but you can try to Hide. You could also Dash or Dodge, or Disengage to avoid the opportunity attacks of a kraken. Maybe there'd be a check to try to repair a damaged component (but repairing damage should be harder than inflicting it).

The ship gets its own attacks automatically, but you might make use your action and make an attack roll to try to score a critical hit to mess with a ship component, or even to hit a specific creature on the other ship.

Once the ships end a turn adjacent, you end the 'naval combat' portion and switch to tactical combat. If one ship succeeded a maneuver to 'grapple,' they decide where to position their ship relative to the other, but have to be adjacent. Otherwise the ships start twenty feet apart. (This part I'm not sure about.)

Pros of this idea? It plays out naval combat with rules very similar to existing D&D.

Cons of this idea? One captain gets to have most of the fun. There might not be enough meaningful options for the players to choose from.

Option Two - Set the Parameters of the Battle
Three steps, all abstracted.

First, the game master determines if there's any chance to avoid a combat. If so, the commander of each side makes an opposed check, each using whatever ability score they want. The game master might impose disadvantage if one side is slower or in a bad position, or grant advantage if they have a clever idea. The winner decides if there's a combat.

Second, if there's a combat, the commanders again make opposed checks, but can use different ability scores. The winner decides how the ships are arranged. Are they side by side for a boarding action? Separated by a small gap? Are two ships pincering another, or did perhaps one ship manage to split the enemies so it's only facing one while the other slowly approaches.

Third, each ship gets one attack (with some really scary ships getting two). If there are multiple ships on a side, you choose where you damage goes. Damage doesn't mean Hit Points, though. If you hit, you inflict some condition on the enemy ship: a fire that is rapidly spreading, a teetering mast, a strike below the water line that causes the ship to list, or damage to some special component like a wizard's study or something.

Then the boarding action happens. Each side gets special benefits based on the ability score or scores their commander used for their checks. The main benefit is to place terrain, which can be on either ship, or even in the water.

Str - Place 12 squares of hazardous terrain - like shattered beams or fires that can cause damage if you move through the area, or firedust that can explode if damaged

Dex - After seeing where the enemies are but before rolling initiative, three characters on your side can use their full movement, perhaps leaping between ships or moving to cover.

Con - Place 12 squares that can provide cover, like fallen debris or stacks of crates.

Int - Place 12 squares that provide concealment, like drifting smoke or loose sails.

Wis - Place 12 squares of difficult terrain, like cracked deck planks or mats of seaweed that washed ashore.

Cha - After seeing where the enemies are but before rolling initiative, three characters on the other side are immobilized on the first turn of combat, perhaps from suppressing fire pinning them down or a confusion about whether they're supposed to attack.

Pros of this idea? Really fast to resolve, lets the players naturalistically collaborate to tweak the battlefield. Quirky.

Cons of this idea? Player choices don't influence the 'ship to ship' part of the battle that much. It's detached from existing game mechanics.

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Any thoughts?
 
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Just a few quick thought right now.

In general I prefer Option 2, but I'd like to suggest an expanded version or maybe Option 3 that combines a bit of the 1st into the 2nd.

The chance to avoid should not be so simple. It can be if the speeds are vastly different, but even if the speeds are the same and you can't be caught, it doesn't mean that the other ship gives up immediately. It would take terrain or night to escape.
You would also need to clarify what proficiency as ship captain does verses not. Somethings should be for trained users only.

I'll be back with more later.
 

I did some different thing in a naval vs. air battle, which should also work in naval vs naval. It is occupying all the players also.
First define the weaponry, use ballista 4d10 area of effect line, dex save avoids, DC =10+Dex mod + prof of the archer, reload 1 rd. , up to catapult 16d20 area of effect line and impact 10' diameter dex save for half damage, DC=10 + Dex mod+prof of operator reload 5 rd. Make some other war machines in between those limits, fitted to your groups level. reach is 500/1500 for medium and long.

Area of effect line means the projectile will deal damage on every living being in its line of firing but stop motion on impact of a specifically targeted being or structure, or on hitting any structure in between.

If someone targets a living opponent he got to make an attack roll using the devices, the dex saves still apply on a hit. Else the machines deal structural damage make a dex check DC 10 or 15 for medium or long range. Save of the ships captain applies. Attach structural HP to the ships (200-2000)

You can submit cannons instead of the more medieval war machines. They need gunpowder then, the amount depending on the size, eg. 1 barrel for the biggest and 1/5 barrel for the one with the ballista stats.

Have 1 player man the helm of a ship the others man the weaponry. The weaponry can allow prof in martial weapons, so it is probably making sense to arm the helm with some wizard PC or so.

You can add additional rules like a ship only maneuvering at half speed if it lost half of its structure etc.

Use some kind of battle map to trace the positions. The ship speeds of 400 to 600 you suggested seem a bit high on first glance, I might be wrong there though.

As you can see my approach also supports individual interaction like the sharpshooter engaging into the battle with his normal ranged weapon, or a caster with some spell in real time. I like that better than some abstract set of rulings.
 

I actually want to avoid having the PCs take their own class based actions in naval combat, because that encourages weird, hard to run close-but-not-melee combat where you snipe enemy crew or whatever. And then if you extrapolate that, you have a hundred people with bows feathering each other and not boarding.

While that could be an intense scene in a movie or video game, D&D isn't designed for it. Most characters would have nothing interesting to do at that range.

That's why I set my round to one minute and the scale to 1 square equals 100 feet. Most attacks in 5e can't even reach 100 feet, and if you get adjacent we hop to normal combat. Also, late medieval sailing ships could top out at about 8 knots, which is a Dash if your speed is 400 feet.

And by making ships creatures, it's easy to have fights with multiple ships, or with, like, a pair of sea serpents attacking the party.

I think 5e combat has the right amount of complexity, and I want that same level of complexity for naval combat. But since the game isn't primarily naval, I don't want to make proficiencies in vehicles that critical.
 
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I‘ve statted up settlements and Squads as ‘characters/monsters’ which acts as a Mount for the Captain/Leader. I find that it works well in letting PCs do there thing while the monster/mount gets a turn of play as well.

As such I like the Ship as Monster proposal above, I’d probably set up Ship maneuverers as Skill challenges where each PC crew member gets to roll there contribution to overcome the challenges - manuvere, attack, defend, disengage, flee.

Personally I’d focus on getting to the Boarding action so PCs getting to shine in rp (your Option 2 tactical aspects are nice :))
 


I‘ve statted up settlements and Squads as ‘characters/monsters’ which acts as a Mount for the Captain/Leader. I find that it works well in letting PCs do there thing while the monster/mount gets a turn of play as well.

I've already got statblocks for a challenge 1 'police squad' (a Large creature representing 10 guys) and challenge 3 'military troop' (a Huge creature representing 25 guys). I imagine once you get to a boarding action, the GM might use a couple of of those (or something similar) to represent clusters of crew if the PCs are outnumbered. If the party has their own crew, you can assume they're busy with each other while the party faces the enemy officers.

As such I like the Ship as Monster proposal above, I’d probably set up Ship maneuverers as Skill challenges where each PC crew member gets to roll there contribution to overcome the challenges - manuvere, attack, defend, disengage, flee.

I probably should do some quick practice encounters with some friends, to make sure that's actually, like, meaningful and fun. I want to avoid asking people to roll a bunch of dice if the dice aren't tied to some specific action or effort. Like, if I said, "You must succeed three checks to ram them," then . . . what? Do we have a bunch of PCs rolling Dex (Vehicles) checks against DC 10, hoping not to fail?

I think it's simpler, and probably more viscerally satisfying, to say, "Make your Vehicles check, and if you succeed, you ram them." One check is all you need.

Personally I’d focus on getting to the Boarding action so PCs getting to shine in rp (your Option 2 tactical aspects are nice :))

Thank you.
 




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