-
The VOIDRUNNER'S CODEX is coming! Explore new worlds, fight oppressive empires, fend off fearsome aliens, and wield deadly psionics with this comprehensive boxed set expansion for 5E and A5E!
D&D General How many air-blown waterskins are needed, if wearing metal armors, to prevent sinking in water?
- Thread starter greg kaye
- Start date
Ancalagon
Dusty Dragon
That's quite easy.
Take the weight of your armor - say it's 25 kg. To return to buyoancy, the air skin must displace an amount of water that weights 25 kg - so 25 litres of air is needed.
edit: I was bracing myself for complicated math, but it is one of those where it turns out to be quite simple. And yes, it's simple with kg and litres, a little bit less so with pounds and gallons. Don't blame me for the USA's inability to switch to metric.
Take the weight of your armor - say it's 25 kg. To return to buyoancy, the air skin must displace an amount of water that weights 25 kg - so 25 litres of air is needed.
edit: I was bracing myself for complicated math, but it is one of those where it turns out to be quite simple. And yes, it's simple with kg and litres, a little bit less so with pounds and gallons. Don't blame me for the USA's inability to switch to metric.
greg kaye
Explorer
That's pretty spot on for 5e chainmail for which 12 waterskins would be needed.
calcs:
A 5e waterskin is described to be able to contain 4 pints of liquid.
If that liquid was water it would weigh 4.16 lb (1.89kg).
If the content was air and the skin was in water, it could support 4.16 lb (1.89kg).
Carbon steel's density is about 7.84 g/cm3, pure iron's density is around 7.86 g/cm3
Water's density is 997 kg/m³ (or 0.997g/cm3)
12.68% of the weight of steel will be bouyed by water
weighs and stuff:
| Chain shirt | 50 gp | 13 + Dex modifier (max 2) | — | — | 20 lb. |
| Scale mail | 50 gp | 14 + Dex modifier (max 2) | — | Disadvantage | 45 lb. |
| Breastplate | 400 gp | 14 + Dex modifier (max 2) | — | — | 20 lb. |
| Half plate | 750 gp | 15 + Dex modifier (max 2) | — | Disadvantage | 40 lb. |
| Heavy Armor | |||||
| Ring mail | 30 gp | 14 | — | Disadvantage | 40 lb. |
| Chain mail | 75 gp | 16 | Str 13 | Disadvantage | 55 lb. |
| Splint | 200 gp | 17 | Str 15 | Disadvantage | 60 lb. |
| Plate | 1,500 gp | 18 | Str 15 | Disadvantage | 65 lb. |
Chain mail weighs 55 lb (24.9476kg) and, if we consider this weight to all be of metal, then its weight in water would be ~48lb.
12 waterskins, each containing 4 pints of air, would be sufficient to bear this weight
(as per 12*4.16=49.92).
How I would rule it would be asking how original was the idea at the time provided, what was the narrative obstacle the group was trying to get past, how logical was it to have the required equipment on hand, and what were the potential results to the overarching story were it to succeed and fail.
So for instance... if the character doing this was a crazy inventor Artificer trying out their wacky new invention, then that character would have a much easier time of it because from my perspective, this is the job that PC was created to be able to do. Likewise, if the group has pressing matters elsewhere and every single member of the party had a way to bypass the obstacle of the water in front of them except for one of them, I probably would not care to bog them down in a pointless potential "drowning scene" right now-- it would have just as unneeded a dramatization in the story that slows things down for no actual gain as making sure characters stop to go to the bathroom while adventuring. Do we really need to play out every single time the platemail-wearing PC having to take a 30-minute break to get in and out of their armor just to go poo? No, we just handwave it because it is not important to the story. Likewise, do we really need to play out the experimentation on the buoyancy principles of armor and air just so the group can keep going on towards their actual concern? If they answer is no... then we just maybe do a quick check, acknowledge the creativity of the idea, and then move on.
BUT... if this is just one of many important parts of the current situation the party finds themselves in and is an intricate part of the plan they are undertaking right now... then of course this idea will take front and center on the actions of the group and who knows how many checks will be needed to overcome this obstacle? But at the end of the day... getting a precise "real world" number of waterskins won't be necessary... merely just that the characters involved did or did not figure the answer out.
So for instance... if the character doing this was a crazy inventor Artificer trying out their wacky new invention, then that character would have a much easier time of it because from my perspective, this is the job that PC was created to be able to do. Likewise, if the group has pressing matters elsewhere and every single member of the party had a way to bypass the obstacle of the water in front of them except for one of them, I probably would not care to bog them down in a pointless potential "drowning scene" right now-- it would have just as unneeded a dramatization in the story that slows things down for no actual gain as making sure characters stop to go to the bathroom while adventuring. Do we really need to play out every single time the platemail-wearing PC having to take a 30-minute break to get in and out of their armor just to go poo? No, we just handwave it because it is not important to the story. Likewise, do we really need to play out the experimentation on the buoyancy principles of armor and air just so the group can keep going on towards their actual concern? If they answer is no... then we just maybe do a quick check, acknowledge the creativity of the idea, and then move on.
BUT... if this is just one of many important parts of the current situation the party finds themselves in and is an intricate part of the plan they are undertaking right now... then of course this idea will take front and center on the actions of the group and who knows how many checks will be needed to overcome this obstacle? But at the end of the day... getting a precise "real world" number of waterskins won't be necessary... merely just that the characters involved did or did not figure the answer out.
Man in the Funny Hat
Hero
If they're shaped and colored like bright yellow duckies - two pair.
Oofta
Legend
Since we have a simple calculation thanks to @Ancalagon and @greg kaye I thought I'd go on a slight rant so feel free to ignore 
...
There's a video somewhere I found long ago where a guy (probably in his 50s or older) talks about armor and sinking. In it, he puts on a gambeson that was typically warn under armor followed by a full suit of chain mail. The gambeson basically acted as a life preserver and he could swim easily, although at a slow speed. Eventually the gambeson could have become waterlogged of course but in the short term no extra flotation devices were necessary.
Do what makes sense of course, but it's not that you're just compensating for a suit of armor, it's more complicated than that. The idea that you automatically sink like a stone if wearing armor is not that simple. Especially when it tends to get completely ignored for everyone but the guy wearing heavy armor. Swimming fully clothed, wearing a backpack, carrying some sort of weapon or quarterstaff and possibly a shield is anything but automatic. Pretty much everybody but a monk should have trouble with swimming unless they strip first.
...There's a video somewhere I found long ago where a guy (probably in his 50s or older) talks about armor and sinking. In it, he puts on a gambeson that was typically warn under armor followed by a full suit of chain mail. The gambeson basically acted as a life preserver and he could swim easily, although at a slow speed. Eventually the gambeson could have become waterlogged of course but in the short term no extra flotation devices were necessary.
Do what makes sense of course, but it's not that you're just compensating for a suit of armor, it's more complicated than that. The idea that you automatically sink like a stone if wearing armor is not that simple. Especially when it tends to get completely ignored for everyone but the guy wearing heavy armor. Swimming fully clothed, wearing a backpack, carrying some sort of weapon or quarterstaff and possibly a shield is anything but automatic. Pretty much everybody but a monk should have trouble with swimming unless they strip first.
greg kaye
Explorer
The air inside a bag of holding would be on a different plane of existence so I'd say no.
However, an "empty" bag of holding might be considered to contain 64 square feet of air and, underwater, if you could catch the air (and fill the bag with something like water) then that would provide loads of buoyancy. I had considered this in an underwater campaign in case there was ever a situation where we wanted to get something heavy from the sea bed just to get back up to the surface quickly.
A barrel can contain four cubic feet of material. If just 8 barrels of air were kept in a Bag of holding then that would give 32 square feet of air. If we don't consider air compression at depth, then each barrel could give 62.41 Lbs of buoyancy with 8 barrels providing a total of 499.28 lbs of lift. If a means was devised to catch all the air from a bag of holding, that could give close to 1000lbs of lift. That's a lot of armour.
Last edited:
Similar Threads
