Wall of Force ≠ immobile ?

[rianalnn]

Too much time in the lab has me struggling with the fact that RAW, Wall of Force is not immobile. My understanding is that spells only do what they say (e.g. Wall of Fire does not catch the forest on fire - it's magic fire & behaves).

Compare Forcecage, which outright states it is immobile.
I see lots of assumption (including previously, my own) that WoF does claim immobility, but it does not.

I ask because it seems like a world with vehicles & Wall of Force is a dangerous & violent world. My table are intent on scuppering the first pirate ship they see moving at speed now that they have access to the spell. Having reviewed, I expect I will rule that the ship pushes the unsecured, "free floating" wall along.

Then I start wondering how strong you need to be to push a Wall of Force. I am thinking, it's a contested roll like grappling, spellcaster vs Sir Leg Day :smallsmile:

I understand why scouring the internet for this discussion has turned up fruitless - the RAI seems "obvious". Except, spells do what they say they do, no more (Wall of Fire does not burn the forest down, because magic/RAW). Maybe it has been discussed, beyond the Wall of Wall of Force Threads a few pages back in this forum?

Thoughts?

[llama-hedge]

In earlier editions, the spell did in indeed specify that the wall was immovable, so that's probably what was intended. As a player who has been on the wrong end of that exact use-case, I'd say it's fine as long as they understand that turnabout is fair play.

[Mastikator]

There are no rules for moving it. One interpretation of that is that it is therefore immovable by default. Another interpretation of that is "the DM decides". The DM decides which interpretation they prefer :smallsmile:

[rianalnn]

Yeah, deciding is where I'm at.

I'd argue that WotC deliberately removing the "can't be moved" text speaks to intent to open this very discussion (& nerf a fairly borked spell), & it doesn't seem fun to me that a single spell shuts down every ship encounter catastrophically.

The idea of turnabout... I guess I could go there but it breaks the world for me. The threat mid-level wizardry represents to navies would necessitate anti-magic knobs or counterspelling/disintigrating mages on the bow of every ship. I guess a campaign world could be built around that, but we've invested heavily on sea travel being dangerous because of normal piracy & wet monsters. Reorienting the entire maritime ecosystem around a single spell seems like the lesser option when The Prow Pushes The Wall Aside is right there for the taking :smallbiggrin:

Thanks for the replies, gang. Feeling confident in the direction my table will sail from here!

[coredump]

I think it comes down to 'words have meaning'.

If you conjure a boat, it is assumed it can float. Because that is how 'boats' work.

Likewise, walls, by their nature, do not move. The walls of the castle do not move, the walls of the prison do not move, the walls of the...whatever... do not move. And we don't have to specifically state that they don't move.

If you check out Wall of Stone, I see nothing there that says it is 'immobile', so can you move the wall of stone?

Wall of force does have one curious addition.... it can me 'free floating'. That does seem to indicate that the force of gravity has no effect on it.... which may imply that it is magically held in the exact same spot, regardless of any outside forces upon it. (Or it may only be immune to gravity)

[Sherlockpwns]

I’m not sure my reply will get to the core of the issue but…

I agree with the concept that walls don’t move, but that is not the same as walls can not BE moved.

For instance if you cast wall of stone on a moving platform (the entire wall on the platform) I would expect the wall to be moving with the platform.

I guess the core question is what is a wall of force “attached” to? Whatever that is would essentially be how hard it is to move. Water, I imagine, would not make a good anchor. Jagged rocks however, well maybe you have something there.

So if I understand the original question a pirate ship that suddenly has a wall of force appear in front of it in the middle of the ocean would just move the thing along with the water, whereas if you could attach it to something more solid like the sea floor, rocks, a reef, the ship would hit it like it was a real wall and many sailors would have a very bad day.

[MoiMagnus]

One could argue that the wall of force is maintained through a variant of telekinesis. So one could also look at the Telekinesis spell for limitations on how easy it is for something to forcefully live things wall against the caster's will.

[animorte]

it doesn't seem fun to me that a single spell shuts down every ship encounter catastrophically.
I mean, everything has a hard counter, right?

Right?

*pulls out my abacus

[Jophiel]

I think it comes down to 'words have meaning'.

If you conjure a boat, it is assumed it can float. Because that is how 'boats' work.

Likewise, walls, by their nature, do not move. The walls of the castle do not move, the walls of the prison do not move, the walls of the...whatever... do not move. And we don't have to specifically state that they don't move.

That would be my take. If the Wall was intended to be moveable, there would be mention of a DC strength check, etc in there. If you are planning on making Wall of Force unsecured, I'd tell the party ASAP and be ready for them to feel like you're just DM fiat'ing away their idea (and the traditional reading of the spell) for your convenience because that's how it would feel to me.

[Dr.Samurai]

I mean, everything has a hard counter, right?

Right?

*pulls out my abacus
This is what I live for lol.

[da newt]

If magic walls don't move then any wall spell will hard stop a ship if you cast it on one.

What if it's free floating about 5' above the deck of the ship and oriented like this --- instead of the traditional [? Does it take out all the sails/masts/rigging?

How much does a wall of force weigh?

I cast wall of ice on the main mast (~57,000 lbs) = capsize or broken main mast falling. I cast wall of stone on the far port side of the forecastle in a big stack of 10x10 plates (~82,500 lbs).



For a nautical campaign, I'd think discussions like this should be a session 0 type discussion. These sorts of things shouldn't be an in game discovery or surprise to the players. Everyone should be involved in creating the 'right' ruling for these sorts of things. Once you are all agreed/aware, then any ruling is fine.

[Wintermoot]

First Officers Log: Day 38.

38 days we have been trapped here, in this hellish sargasso sea. As near as we can figure a great battle took place some age ago between titanic spell casters and they left hundreds of free floating walls of force. Some vertical, some elevated off the sea, some canted at bizarre angles. In the dull clouded light, they are nigh invisible until you are right upon them. Already we have seen our sister vessels shorn and sunk. All sails are in, all masts, that remain, have been removed and stowed. All we can do is stand ready with poles to the man and slowly work our way through this "force-berg" abyss hoping for an end to come.

[Segev]

First Officers Log: Day 38.

38 days we have been trapped here, in this hellish sargasso sea. As near as we can figure a great battle took place some age ago between titanic spell casters and they left hundreds of free floating walls of force. Some vertical, some elevated off the sea, some canted at bizarre angles. In the dull clouded light, they are nigh invisible until you are right upon them. Already we have seen our sister vessels shorn and sunk. All sails are in, all masts, that remain, have been removed and stowed. All we can do is stand ready with poles to the man and slowly work our way through this "force-berg" abyss hoping for an end to come.

Nice mini-story!



Personally, I tend to like to treat spells like this as immobile, but referenced to whatever makes sense. This CAN lead to edge case quesitons of just how big a vehicle has to be to attach a Leomund's tiny archer hut to it, or to use cases of a wall of force at the prow of a ship to make it better at ramming, but overall it leads to fewer "gotcha" situations. (You don't want, in a ship scene where you're literally using the ship as the battlefield, to have to calculate drift on the wall of force or the Leomund's tiny hut or the magic circle.)

The way to handle edge cases is to treat the rules as just as fuzzy as the edge case is. If force effects can semi-unpredictably shift from stationary wrt your vehicle to being stationary wrt the water below, they become hazardous to use, but not impossible. "Don't remind the magic that there are other things moving that are just as big," might be the rule that mages teach their apprentices.

[KorvinStarmast]

There are no rules for moving it. One interpretation of that is that it is therefore immovable by default. Another interpretation of that is "the DM decides". The DM decides which interpretation they prefer :smallsmile: Yes.


I'd argue that WotC deliberately removing
I doubt it was deliberate. As I reviewed the editing quality on the three core books, I was left unimpressed. It went down hill from there.

If the Wall was intended to be moveable, there would be mention of a DC strength check, etc in there.

[Mastikator]

If I wanted to nerf wall of force, and I do, I'd give it armor class and hitpoints. So let's see, a wall of stone has 15 AC and 180 HP per panel and has 6 panels, but really destroying one generally does the trick. So let's go with 15 AC and 360 HP for the whole thing.
Plus 30 and 1 AC per spell level?

Force cage? I'd go with 360 hp and 15 AC, same increase per level, since it has anti-teleportation built in it's only fair that it's a bit more fragile.

[KorvinStarmast]

If I wanted to nerf wall of force, and I do, I'd give it armor class and hitpoints. So let's see, a wall of stone has 15 AC and 180 HP per panel and has 6 panels, but really destroying one generally does the trick. So let's go with 15 AC and 360 HP for the whole thing.
Plus 30 and 1 AC per spell level? I'd add a damage threshold which structures and ships tend to have.

While this approach would negate the lovely cheese that we pulled off a while back [Sickening radiance cast by warlock and WoF cast as a reaction by the wizard, which Exhausted a dragon to death] it retains the wall of force's initial ability to block bad things, at least for a while, as a way to cover a retreat or to try and corner/trap a foe.

[kazaryu]

Yeah, deciding is where I'm at.

I'd argue that WotC deliberately removing the "can't be moved" text speaks to intent to open this very discussion (& nerf a fairly borked spell), & it doesn't seem fun to me that a single spell shuts down every ship encounter catastrophically.

The idea of turnabout... I guess I could go there but it breaks the world for me. The threat mid-level wizardry represents to navies would necessitate anti-magic knobs or counterspelling/disintigrating mages on the bow of every ship. I guess a campaign world could be built around that, but we've invested heavily on sea travel being dangerous because of normal piracy & wet monsters. Reorienting the entire maritime ecosystem around a single spell seems like the lesser option when The Prow Pushes The Wall Aside is right there for the taking :smallbiggrin:

Thanks for the replies, gang. Feeling confident in the direction my table will sail from here!

one way i've considered running spells like that is to have them lock on such that they're immobile relative to something else. thus allowing them to be used in fights on moving things like ships. The other thing it does is allow them to function in settings where you do actually have planets that are rotating. my point being that if a caster wanted to make a wall of force that would be immobile over the water, they'd need to personally be using the water as their reference point. (meaning at the very least they'd need to be stationary over the water rather than the ship.

[Calen]

If magic walls don't move then any wall spell will hard stop a ship if you cast it on one.

What if it's free floating about 5' above the deck of the ship and oriented like this --- instead of the traditional [? Does it take out all the sails/masts/rigging?



I did run into this exact situation, as well as angled walls to try to "beach" a ship.

I ruled that ships would take some force damage when impacting a wall, they could be slowed by impact but trapping anything larger than a rowing boat was not possible.

The players were cool with that and the wizard continued to use them for "crowd-control" of the enemy ships throughout the campaign.

[Mastikator]

I'd add a damage threshold which structures and ships tend to have.

While this approach would negate the lovely cheese that we pulled off a while back [Sickening radiance cast by warlock and WoF cast as a reaction by the wizard, which Exhausted a dragon to death] it retains the wall of force's initial ability to block bad things, at least for a while, as a way to cover a retreat or to try and corner/trap a foe.

I think that's fine. You could even let the caster use their action to regenerate 30 hit points while concentrating. It's not going to tip the balance even slightly when a raging barbarian with GWM and a fighter with SS is trapped. At most they'll get out in 3-4 rounds. In combat 3-4 rounds is an aeon, outside of combat it's 18-24 seconds.

[OracleofWuffing]

This is admittedly an unfair apples to oranges comparison, but immovable rods are moveable. I would personally interpret the resilience of a Wall of Force somewhere in the same ballpark, more or less.

[rianalnn]

Yes, haha, words have meaning (*cough chill touch *cough*) :smalltongue:
First Officers Log: Day 38.

38 days we have been trapped here, in this hellish sargasso sea. As near as we can figure a great battle took place some age ago between titanic spell casters and they left hundreds of free floating walls of force. Some vertical, some elevated off the sea, some canted at bizarre angles. In the dull clouded light, they are nigh invisible until you are right upon them. Already we have seen our sister vessels shorn and sunk. All sails are in, all masts, that remain, have been removed and stowed. All we can do is stand ready with poles to the man and slowly work our way through this "force-berg" abyss hoping for an end to come.Amazing.


Really appreciate the discussion! My table were all new to 5e when we started, & I was the only one with (2e) D&D experience, so it's been a journey of discovery, to say the least.

[Lunali]

As an alternate interpretation, the wall is immobile, but no damage is caused when you crash into it. The wall of force exerts a force on the object that hits it, causing the object to stop, or rather to stop moving in the direction of the wall. This would lead to an interesting effect where something hits the wall at an angle and then has part of its momentum negated, leaving it moving parallel to the wall as if it were sliding.

[Tanarii]

one way i've considered running spells like that is to have them lock on such that they're immobile relative to something else. thus allowing them to be used in fights on moving things like ships. The other thing it does is allow them to function in settings where you do actually have planets that are rotating. my point being that if a caster wanted to make a wall of force that would be immobile over the water, they'd need to personally be using the water as their reference point. (meaning at the very least they'd need to be stationary over the water rather than the ship.
Sounds like you're saying they should be immobile relative to the casters frame of reference? So if they're on a ship, if they cast it at range on the surface of another ship, it moves with the casters ship, not the target ship?

[Jophiel]

As an alternate interpretation, the wall is immobile, but no damage is caused when you crash into it. The wall of force exerts a force on the object that hits it, causing the object to stop, or rather to stop moving in the direction of the wall.
I like this and would use it this way for naval combat. Wall of Force will stop a ship from moving forward but not the same way as crashing into a cliff would. This also stops applications like a WoF "blade" shearing through the masts. It feels like a good middle ground where WoF works primarily as expected but isn't a superweapon using the ship's mass and momentum against it.

[kazaryu]

Sounds like you're saying they should be immobile relative to the casters frame of reference? So if they're on a ship, if they cast it at range on the surface of another ship, it moves with the casters ship, not the target ship?

i don't know if im saying it 'should' moreso than im saying that that is one way i've considered running it, so that the spell can still be used as intended for combat aboard moving objects like ships.

But yes, what you're saying is accurate other than that. and yes, that would be a consequence of running it that way.

[Slipjig]

to use cases of a wall of force at the prow of a ship to make it better at ramming

The flaw in this idea is that the wall would push on both ships equally. So if you allow your ship to push a Wall of Force, the other ship should be able to exert equal force on it, so you just end up with both ships being wrecked.

But I'm also of the school that walls of fire set combustible things alight, walls of blades cut inanimate objects, and a wall of ice can chill your drink. And none of them move.

I mean, if you could anchor a wall spell to a movable object, what prevents a caster from anchoring it to his wand and smacking people with it?

[Slipjig]

Sounds like you're saying they should be immobile relative to the casters frame of reference? So if they're on a ship, if they cast it at range on the surface of another ship, it moves with the casters ship, not the target ship?

I think that opens up a ton of ridiculous cases that make this an even more broken spell. If a caster is riding a charging horse, can he make his "frame of reference" his horse's saddle and act like a giant snowplow on everything in front of him? What happens if he charges directly at a castle wall or a building? Does he knock it down?

Can a flying wizard define his point of reference as his belt buckle, and do the same thing in the air?

It's a wall. With very few exceptions, walls don't move.

[KorvinStarmast]

I think that opens up a ton of ridiculous cases that make this an even more broken spell. If a caster is riding a charging horse, can he make his "frame of reference" his horse's saddle and act like a giant snowplow on everything in front of him? What happens if he charges directly at a castle wall or a building? Does he knock it down?

Can a flying wizard define his point of reference as his belt buckle, and do the same thing in the air?

It's a wall. With very few exceptions, walls don't move.It is actually two different things.
1. It's a wall.
2. It is a 10' radius sphere.

[PhoenixPhyre]

I think that opens up a ton of ridiculous cases that make this an even more broken spell. If a caster is riding a charging horse, can he make his "frame of reference" his horse's saddle and act like a giant snowplow on everything in front of him? What happens if he charges directly at a castle wall or a building? Does he knock it down?

Can a flying wizard define his point of reference as his belt buckle, and do the same thing in the air?

It's a wall. With very few exceptions, walls don't move.

Yeah. I'd say you have two possibilities, with the first entirely for convenience.

1. If you are on a moving vessel that is large and stable (ie a large ship) and you are placing it completely within the area of the vessel (ie on deck), it "sticks" to the deck.
2. Otherwise, it is stationary relative to the ground.

And since it doesn't say that running into it causes damage...it doesn't. A ship that runs into a wall of force placed relative to the sea...just stops. Remember, in D&D world momentum is very much not conserved. At least not mechanically. Because if it was, all sorts of things would go very very badly. Including any teleportation, including short-range stuff.

[kazaryu]

I think that opens up a ton of ridiculous cases that make this an even more broken spell. If a caster is riding a charging horse, can he make his "frame of reference" his horse's saddle and act like a giant snowplow on everything in front of him? What happens if he charges directly at a castle wall or a building? Does he knock it down?

Can a flying wizard define his point of reference as his belt buckle, and do the same thing in the air?

It's a wall. With very few exceptions, walls don't move.

1. he was replying to me...so all of your complaints should be directed at me.

2. we're talking about homebrew, the written word of a rule isn't whats important, what you *should* look at is what is obviously intended by the rule, and i made the intent of my suggestion pretty clear.

3. none of those apply since...no, the implication wasn't that you can choose what your frame of reference is. your frame of reference is your perspective frame of reference. you don't move relative to your horse while riding your horse. your frame of reference (in that case) would still be the ground. Literally the point, as i stated it, was that it allowed spells like wall of force to be used as they were intended on things like ships. so if your ship gets boarded while its moving you can still cast a wall spell and not have it immediately leave the vicinity of the ship. or cast a spell like levitate without having to worry about flying overboard (although that could be argued to be saved by just basic momentum, as long as the ship doesn't turn).

the only edge cases that could possibly apply is when you have other objects moving relative to your frame of reference, i.e. a second ship that is moving faster than yours, or coming in from a side angle.

[Segev]

The flaw in this idea is that the wall would push on both ships equally. So if you allow your ship to push a Wall of Force, the other ship should be able to exert equal force on it, so you just end up with both ships being wrecked.

I can see where you're coming from, but consider this: I cast, in a dungeon, wall of force. It is free-floating in the middle of a 15x15 tunnel of cut stone. A huge creature, capable of smashing through walls of stone, comes up to it, and smashes all its might into it. Does this cause the ground and walls and ceiling near the wall of force to crumple and bend and break, allowing the wall of force to be pushed back relative to myself and the huge creature, but stay put relative to whatever dungeon parts there were?

What if I cast it in the hold of a huge ship at sea? If said monster slams into the wall of force with enough force to shove the ship, does it shatter the ship's hull? Push the ship back? Or just hit the immovable wall and do nothing, because it's a wall of force?

The "use it as a ramming prow" trick would be something akin to putting it out in front of the spar, touching nothing. Used from a "the boat is stationary" perspective in open sea, it would just be a defense against cannon fire from that direction, or the like. Or against other ships ramming it from the front. So if that ramming vessel tries to slam into our boat from the front, the wall of force just stops it dead cold. But what if our boat is the one moving? Well, one idea is that the wall isn't, so the boat slams into it. But that's back to the question of what the wall is stationary relative to, and why. That interpretation could easily make Leomund's tiny hut cast on the ship's deck for a comfortable place to sleep wind up sweeping the aftcastle right off the boat as the boat keeps moving and the dome does not! More "instinctive" would be the dome being stationary on the boat's deck.

Ultimately, corner cases like the wall of force being outside the boat or being used as a ram prow are where rulings like yours - suddenly, both boats are slamming into the wall - become reasonable compromises as the magic is "reminded" that it's being exploited weirdly.

[Chronos]

Quoth coredump:

Likewise, walls, by their nature, do not move. The walls of the castle do not move, the walls of the prison do not move, the walls of the...whatever... do not move.
The walls of the ship's cabin...

A lot of these same questions come up with Immovable Rods, but in that case, at least, I realized I had accidentally come up with the answer without knowing it at the time. I didn't actually give my party an Immovable Rod; I gave them a blueprint for an Immovable Rod. And every magic-item blueprint should include at least one hard-to-get component, to prevent mass-production, and for the Immovable Rod, I chose "a stone from the uttermost pinnacle of a mountain, that has been at the uttermost pinnacle for at least 50 years". So for my party's Immovable Rod, it's immovable relative to Mount Waterdeep (that being where they got their stone from).

(Later, my party also visited the peak of a different mountain, but at the time, everyone, myself included, forgot that they had that blueprint, and so neglected to get another mountainpeak stone.)

[JackPhoenix]

While only tangentially related to WoF's (im)mobility, interesting (if nitpicky and rule-lawyery) argument for crashing ships into WoF is that ships can crash when they run into creatures or objects, but it's not clear if WoF does actually count as an object.
"an object is a discrete, inanimate item like a window, door, sword, book, table, chair, or stone, not a building or a vehicle that is composed of many other objects."
Now, WoF is discrete and inanimate, but is it really an item? As far as we know, it's got no physical substance... it's a force (by definition "strength or energy exerted or brought to bear : cause of motion or change : active power.") that applies in a certain area, a magical effect (Dispel Magic lists magical effect as possible target separated from objects or creatures, not that it works on WoF) but not an object. The ship certainly can't physically pass through, but by strict reading, it doesn't take damage from crash either. How does that work? Magic.

[CapnWildefyr]

The idea of turnabout... I guess I could go there but it breaks the world for me. The threat mid-level wizardry represents to navies would necessitate anti-magic knobs or counterspelling/disintigrating mages on the bow of every ship. I guess a campaign world could be built around that, but we've invested heavily on sea travel being dangerous because of normal piracy & wet monsters. Reorienting the entire maritime ecosystem around a single spell seems like the lesser option when The Prow Pushes The Wall Aside is right there for the taking :smallbiggrin:

Thanks for the replies, gang. Feeling confident in the direction my table will sail from here!

Lots of good content replies here already, but for this part of your question -- you don't have to exactly 'reorient the maritime ecosystem' if WoF is immovable vs the ship. Ships are treasure. The ship might in fact be worth more than the cargo it's carrying. It's one thing for navies in a war to destroy ships, quite another for pirates, half of whose goal is salvaging the captured ship. Also applies to smart or greedy PCs. So if you rule that a WOF flatlines a ship, telling the PCs "As the ship sinks, and you listen to the delicious sounds of your evil mortal enemies drowning, one of your sailors approaches you and says, "Um, pardon, m'lord, but why'd we just send 25,000 gp to Davey Jone's locker? Me and the mates, y'know, coulda used our share of salvage. And what if they was carryin' prizners?"

Some maritime 'realignment' would be needed, but even with navies, will every ship have a spellcaster who also happens to know WoF? And WoF's range is 120 ft. Certainly within bowshot if the caster is not hiding somewhere. And certainly there are lots of ways in ship-to-ship combat to force casters to make concentration checks.

[Rukelnikov]

Yeah. I'd say you have two possibilities, with the first entirely for convenience.

1. If you are on a moving vessel that is large and stable (ie a large ship) and you are placing it completely within the area of the vessel (ie on deck), it "sticks" to the deck.
2. Otherwise, it is stationary relative to the ground.

And since it doesn't say that running into it causes damage...it doesn't. A ship that runs into a wall of force placed relative to the sea...just stops. Remember, in D&D world momentum is very much not conserved. At least not mechanically. Because if it was, all sorts of things would go very very badly. Including any teleportation, including short-range stuff.

Does it say anywhere that running into a wall at full speed causes damage? I don't think so, any character can go as fast as they want and smash head on against any wall without sustaining damage.

[PhoenixPhyre]

Does it say anywhere that running into a wall at full speed causes damage? I don't think so, any character can go as fast as they want and smash head on against any wall without sustaining damage.

This kind of equivocation between rules-based and "realistic" thinking always causes issues. My general principle is that for game purposes, effects generally do what they say they do and don't do what they don't say they do. Where appropriate, I'll extend that. But always in line with the fiction, and not in a way that arbitrarily gives some features bunches of extra power. But ignores all the other consequences because they're not convenient.

In other words "because magic" cuts both ways. If magic can break the normal rules...it has to set its own rules. And you can't refer back to the rules (ie physical laws) you ignored by being magic in the first place. Because you already discarded those to be magic.

So the two are inappositely compared here.

[Rukelnikov]

This kind of equivocation between rules-based and "realistic" thinking always causes issues. My general principle is that for game purposes, effects generally do what they say they do and don't do what they don't say they do. Where appropriate, I'll extend that. But always in line with the fiction, and not in a way that arbitrarily gives some features bunches of extra power. But ignores all the other consequences because they're not convenient.

In other words "because magic" cuts both ways. If magic can break the normal rules...it has to set its own rules. And you can't refer back to the rules (ie physical laws) you ignored by being magic in the first place. Because you already discarded those to be magic.

So the two are inappositely compared here.

Im just following your logic.

[Mellack]

A bit of math on having ships able to move the WoF. :smallsmile:

Start with the assumption that a ship can move a Wall of Force it runs into. So Ship > WoF. What move a ship? The wind. A viking ship has about a 800 sq ft sail and can move with as little as a 5 knot (5.7 mph) wind. The wind can move the ship. So Wind > ship. Since WoF has up to 1000 sq ft (more than a ship), it logically would have to also be moved by the wind that is able to move the ship (under our assumptions that ships can move the wall).
Wind > Ship > WoF

End result, if ships can push around a WoF, then a gentle breeze will also be pushing them around. They would be flying around like an unsecured bounce house.

[Scarytincan]

Might also be worth taking a look at collision rules for ships, can use those when hitting a wall based on the size of the ship itself for damage

[JackPhoenix]

A bit of math on having ships able to move the WoF. :smallsmile:

Start with the assumption that a ship can move a Wall of Force it runs into. So Ship > WoF. What move a ship? The wind. A viking ship has about a 800 sq ft sail and can move with as little as a 5 knot (5.7 mph) wind. The wind can move the ship. So Wind > ship. Since WoF has up to 1000 sq ft (more than a ship), it logically would have to also be moved by the wind that is able to move the ship (under our assumptions that ships can move the wall).
Wind > Ship > WoF

End result, if ships can push around a WoF, then a gentle breeze will also be pushing them around. They would be flying around like an unsecured bounce house.

Reminds me of that time back in 3.5 when I calculated it's cheaper to make a castle fly with big enough baseplate and Control Winds (I think? Some sort of wind-producing spell, it's been a while) than to enchant it to fly on its own.

[Jophiel]

Does it say anywhere that running into a wall at full speed causes damage? I don't think so, any character can go as fast as they want and smash head on against any wall without sustaining damage.

We have real world frames of reference for material walls made of stone, wood or iron. A floating force field, however, has a lot more room for DM discretion without sacrificing verisimilitude when it comes to smashing your face into a brick.

[Segev]

A bit of math on having ships able to move the WoF. :smallsmile:

Start with the assumption that a ship can move a Wall of Force it runs into. So Ship > WoF. What move a ship? The wind. A viking ship has about a 800 sq ft sail and can move with as little as a 5 knot (5.7 mph) wind. The wind can move the ship. So Wind > ship. Since WoF has up to 1000 sq ft (more than a ship), it logically would have to also be moved by the wind that is able to move the ship (under our assumptions that ships can move the wall).
Wind > Ship > WoF

End result, if ships can push around a WoF, then a gentle breeze will also be pushing them around. They would be flying around like an unsecured bounce house.

Nice analysis!

That said, it depends on whether the ship is "pushing" the wall of force, or if the wall of force is stationary wrt the ship that is its local environment. The latter is tricky only if you get into edge cases where the ship has to interact with a larger context, and when and how to determine if the wall of force is stationary wrt the ship, or the ocean, or the sea floor, or.....

[Slipjig]

I can see where you're coming from, but consider this: I cast, in a dungeon, wall of force. It is free-floating in the middle of a 15x15 tunnel of cut stone. A huge creature, capable of smashing through walls of stone, comes up to it, and smashes all its might into it. Does this cause the ground and walls and ceiling near the wall of force to crumple and bend and break, allowing the wall of force to be pushed back relative to myself and the huge creature, but stay put relative to whatever dungeon parts there were?
If the creature smashes through the walls or the floor, then the walls or floor are smashed. However, the immobility of the Wall of Force does not depend on being tied to the stone walls or floor, so that makes no difference to the Wall of Force. It remains immobile.

[Chronos]

Mellack, you're not taking into account momentum. If you build a sail-sized wooden wall on a pier, it'll stay in place even against the wind. But if a sailing ship crashes into it, it'll still break through the wall.

[JackPhoenix]

Mellack, you're not taking into account momentum. If you build a sail-sized wooden wall on a pier, it'll stay in place even against the wind. But if a sailing ship crashes into it, it'll still break through the wall.

If a ship crashes into object one size smaller than itself or larger, it'll stop moving. If we go by Mellack's numbers, 800 ft2 would give a square sail dimensions of 28x28'. That would be gargantuan size category, the same category as the largest ships. That means a sail-sized wooden wall can stop any ship crashing into it (and because ships only cause damage to *creatures* they crash into, but not *objects*, the wall would be undamaged, while the ship would potentialy take 16d10 damage from the crash). If the wall was large or smaller (i.e. 2 or more size categories smaller than the ship), the ship would avoid crashing into it and taking damage, but the wall would be moved with the ship or destroyed at the DM's discretion if it's fixed in place.

...

Yeah.

[Mastikator]

What even is the mass of a wall of force? How do you calculate its momentum? Kinda hard to apply Newtonian physics to a non-Newtonian object.

[Segev]

If the creature smashes through the walls or the floor, then the walls or floor are smashed. However, the immobility of the Wall of Force does not depend on being tied to the stone walls or floor, so that makes no difference to the Wall of Force. It remains immobile.

Then the immobility of the wall of force cast on a ship would make no difference to the strength of the ship's hull or other wooden components, and if something smashes into the wall of force, the ship should be fine. Not crumpling just because the wall of force is being pushed against. If the wall of force is stationary wrt the ship for whatever reason, the ship never slams into anything; other things slam into the ship. The same way that an island never slams into anything.

[JackPhoenix]

The same way that an island never slams into anything.

Well... is continental drift a thing?