Post/Author/DateTime	Post
pilight 02-06-05, 05:12 PM	The players have cleared the monsters from a sunken ship, but the treasure was more than they could get out in the duration of their water breathing potions. They know that if they start purchasing bunches of such potions people will take notice, which they really don't want. Their plan is to bell-dive at night to recover the treasure. Anyone have suggestions on how to adjudicate this? What skills would they use and DCs, how long the air inside the bell would last, problems they might encounter, stuff like that.
The Shaman 02-06-05, 06:01 PM	Does this technology even exist in your campaign world? In the real world...doesn't matter - what matters is the campaign world. If the players decided to invent the diving bell, then (1) that could be construed as metagaming and/or (2), it should require a fairly high DC series of Craft and/or Knowledge and/or Profession checks.
pilight 02-06-05, 10:51 PM	It's more basic than that. They're using an actual bell, which they stole from the local Temple of Kord. It's certainly large enough. In the real world, bell-diving predates much of the technology used in D&D (such as crossbows). It was an established practice during the time of Alexander the Great, he used it during the siege of Tyre.
fdnickerson 02-06-05, 11:09 PM	Interesting. Bell diving certainly makes sense if your characters can't afford or don't have access to permanant effect magic items. I would suggest reading up on page 304 of the DMG which covers water dangers. Key skills would be swim and/or survival with fort saves to stay under. Things to consider would be duration underwater, depth (pressure), and how violent the seas are. Its too bad the Maelstrom book isn't out yet. Still the DMg does give a quick half-page overview of it which should give you some idea.
The Shaman 02-06-05, 11:33 PM	In the real world, bell-diving predates much of the technology used in D&D (such as crossbows). It was an established practice during the time of Alexander the Great, he used it during the siege of Tyre. That's true, but what I was trying to explain is that just because something existed in the historical timeline of Earth doesn't mean it has to exist in the campaign-world as well. If you've postulated that diving bells exist in your campaign, that's cool, but often players and GMs bring, "But in my History 101 class, Professor Dingledorfer said...," to the game-table, and there's really nothing that could be less relevant. The game world =/= the real world. As far as checks, well, you need to get a rough idea on how much time they have in the enclosed space before Fort saves to avoid suffocation occur (if no surface-fed air supply) or the DC for the air supply system to work over a time interval (say every ten minutes). You need a barge or similar vessel from which to suspend the bell and a system to raise an lower it - DC for opeating the winch could use Craft or Profession or straight STR. You cannot move the bell laterally very easily, so the players will need to dive down, exit the bell to collect the treasure, and swim back into the bell. You could add a Fort save for decompression or suffer the bends on surfacing - primary and secondary of 1d6 CON damage.
Ssussunriyh 02-07-05, 01:34 AM	If you want to add strictly-accurate realism to it, keep in mind that the air trapped inside the diving bell is still at normal (sea-level) atmospheric pressure, while water pressure increases with depth. The deeper you go, the more the water pressure increases, and the air inside the diving bell gets compressed into a smaller volume. If memory serves, the pressure increases by one atmosphere per 33 feet of depth. Therefore, at a depth of 33 feet the water pressure is two atmospheres, so the level of the water will come halfway up the inside the bell. You can't use a diving bell beyond about 70 feet down, since you'd have nothing but a small bubble of compressed air up inside the top of the bell's interior. Of course, you could just skip the diving bell idea and let them find a friendly NPC who can cast Water Breathing spells on them, in exchange for a cut of the treasure...
Vorel-Aurixsveargith 02-07-05, 01:54 AM	I believe it is actually 1 Atm per 13 feet or so. I'm pretty sure it's that because you can feel it if you hold your breath and dive under water. That's partially what that crushing feeling is. (I might just notice it more because I have massive lung capacity and not much between my lungs and the world.)
Finley DaDum 02-07-05, 03:25 AM	33ft or 10m = an increase of 1 atmosphere Diving below about 150ft without special equipment or in this case magical assisstance (i.e. freedom of movement or the like) is very dangerous. Someone else pointed out that the volume of air inside the bell would be reduced. 1/2 volume @ 33ft 1/3 volume @ 66ft 1/4 volume @ 99ft and so on. Depending on how realistic you want to get breathing Air @ considerable depth can result in Nitrogen Narcosis (which feels and looks to some extent like being drunk). Ascension from depths below 100ft also takes quite a bit of time to avoid "the bends" (basically dissolved nitrogen in the blood expanding to quickly). All in all unless the bell is huge or the wreck is very shallow this plan is fairly unworkable but it really depends on how much realism you want.
ShadowDragon8685 02-07-05, 04:24 AM	How shallow is the wreck? If we're talking the kind of shallow that you can still see the masts poking out of the water, no problem. If we're thinking anything much deeper than that, fuggedaboutit and go for water breathing potions. If someone asks why, tell them you're doing salvage, and give them a DIFFERENT shipwreck.
pilight 02-07-05, 07:04 AM	The wreck isn't very deep, about 150'. It's in an estuary, fairly calm. Thanks for the info on depth limitations. None of the characters has any skills re: diving so they won't know that. As for the existence of the technology, my general theory is that if it existed IRL at the same time as other D&D tech then it exists in my world unless there's a particular reason why it shouldn't. I had never considered the existence of bell diving (who does?) until they made it plain where they were headed. As for permanent magic items, it's a fairly low-magic campaign. The players had an opportunity to get some, they foolishly chose to get magic weapons instead of things to let them breathe underwater. ;)
Art_Tillary 02-07-05, 08:34 AM	While diving bells existed in ancient times (per previous poster), it might not exist later on. It could be a "lost" technology. Similar examples were concrete which was invented by the Romans, but lost during the middle ages until the 18th century (I think that was the re-invent time). I was thinking that with magic availiable, nobody would have thought of a diving bell. As another poster mentioned, they will need a barge to use the bell. They'll also have to get a bell, find a way to communicate with the surface (rope probably), etc. None of this will be easy to hide I'd think. AT
fdnickerson 02-07-05, 12:15 PM	According to the DMG, at 150ft the char takes 1d6 damage per minute unless he makes a fort save (DC 15+1 for each previous check).(DMG p.304) Also, what is the temp? If it's cold the char may take exposure damage. How big is the bell (in cubic ft) and how many people are diving? This will affect the amount of air available.
Art_Tillary 02-07-05, 01:20 PM	According to the DMG, at 150ft the char takes 1d6 damage per minute unless he makes a fort save (DC 15+1 for each previous check).(DMG p.304) Also, what is the temp? If it's cold the char may take exposure damage. How big is the bell (in cubic ft) and how many people are diving? This will affect the amount of air available. For those of us still doing 3.0, it's on page 85 & 86 of the DMG. Now aside from that, the rule makes absolutely no sense. Yeah, I know it's just a game, but game mechanics should at least make some sense. Water pressure while diving doesn't do damage at all. It is the rapid ascent if you breathe air while down there that will kill you. Like a previous poster mentioned, the air in the bell will compress as you go deeper. If you take a breathe of air from the bell you have to ensure you expell it while ascending or your lungs will burst. I suspect the bell won't have enough air to worry about decompression requirements. On the gripping hand, it is below the level of nitrogen narcosis . As such, the characters will act drunk if they take any air from the bell at 100 feet. AT
fdnickerson 02-07-05, 01:49 PM	For those of us still doing 3.0, it's on page 85 & 86 of the DMG. Now aside from that, the rule makes absolutely no sense. Yeah, I know it's just a game, but game mechanics should at least make some sense. Water pressure while diving doesn't do damage at all. It is the rapid ascent if you breathe air while down there that will kill you. Like a previous poster mentioned, the air in the bell will compress as you go deeper. If you take a breathe of air from the bell you have to ensure you expell it while ascending or your lungs will burst. I suspect the bell won't have enough air to worry about decompression requirements. On the gripping hand, it is below the level of nitrogen narcosis . As such, the characters will act drunk if they take any air from the bell at 100 feet. AT Agreed. It doesn't make sense. However, the formula does have one thing going for it. It's simple to implement. The DMG designers are trying to provide a simple formula to describe something very complex. The actual mechanics of it are, in my opinion, too complex to be modelled realistically. Now to work. To model the drunkenness effects of NN compare it to the effects of 1 glass of alcohol for every 50ft below hundred. I don't have the 3.0 guide so I can't tell you where to look for that. Have them make fort saves as mentioned above when rising.
The Shaman 02-07-05, 02:36 PM	The wreck isn't very deep, about 150'. That's actually quite deep - nitrogen nacosis and cold become serious hazards, as others have noted. I've chamber-dived to 160' - it's a heck of a buzz, like a couple of double martinis back-to-back (though it affects everyone a little differently). The DMG damage is way off - I don't recommend using it. Instead apply non-lethal damage from the cold, 1d6 per minute of exposure, unless some sort of magical environmental immunity is available. Water pressure can do damage if the body is suddenly transported to that depth (e.g., teleport), but usually not if the descent is gradual, giving the body time to adjust. You could also use a Fort save (DC 15) to avoid the bends on a normal ascent, DC 25 on a rapid ascent (anything faster than a foot per round as a rule of thumb), with the aforementioned CON damage.
Mister Mayhem 02-07-05, 04:36 PM	Indeed, 150 feet, thats near enough 50 meters (I'm used to dealing with meters when diving.) That's plenty deep enough to suffer nitrogen narcosis. The bends will be a real problem on ascent - but I really can't be bothered to go get my diving charts for this. It will also be cold and dark due to lack of sunlight. And seem even colder, since water conducts heat away from the body an awful lot more efficiently than heat. Volume of air will be 1/5th the volume of the bell at the surface. That's never going to be enough for this stunt to succeed. ***** Now, if they are smart enough to pump air down into the bell to replace that "lost" by compression (or magically generate it), it might just work. And I'm sure they have a way to avoid the cold, and generate light. And you can get acclimatised to the narcotic effects of nitrogen at pressure. With fresh air being supplied to the bell, they will be able to ascend slow enough to avoid the bends. Of course, there is very little chance of the characters actually knowing enough to do this, and the bends is a very, very painful way to die...
Vharuck 02-07-05, 04:58 PM	My question is how are they going to get the bell back up to the surface? I mean, getting it to sink is no problem; gravity does that. But even if they have a team on the surface to hoist it back up, that's not only the bell's weight but also the weight of the water over it they have to pull. Basically this reeks of danger and my guess is one, if not all, of them will end up dead on the bottom of the sea.
Art_Tillary 02-07-05, 05:49 PM	My question is how are they going to get the bell back up to the surface? I mean, getting it to sink is no problem; gravity does that. But even if they have a team on the surface to hoist it back up, that's not only the bell's weight but also the weight of the water over it they have to pull. Basically this reeks of danger and my guess is one, if not all, of them will end up dead on the bottom of the sea. ???? The water that is above the bell is irrelevent. It adds nothing to the weight that has to be lifted. Where did you get the idea that the depth of water above an object has anything to do with how much it takes to lift the object? If the crane on the barge can lift the bell from the pier, it will be able to lift it from the bottom. The only "extra" weight would be the weight of the line used to lower and lift the bell the 150'. AT
Bloodhawk 02-07-05, 10:14 PM	I didn't know so many of us are divers !! Forgive me for speaking out of turn if I am, but I had to respond to this post. All of you are right, either about the pressure, atmospheres, temp all of it could or will derail this operation from happening. We could list hundreds of ways why this will not happen. From reading the original postings I have to say "great job" from the players for creatively thinking around a potential problem and coming up with a plausible solution to this. I am not saying to reward the PCs for thinking up "diving bell", but give them credit, allow them (PCs) to learn. Give them clues and or hints to learn about the dangers of this type of underwater adventuring. If they came up with this solution allow them to develop more based on either in character research or old fashioned trial and error. They came up with this idea and presented it to you in good faith, now work with them to either complete or not complete this undertaking. This is an excellent opportunity to have a fantastic night with heavy duty RPing and your chance to introduce a really unique NPC. Good luck
The Shaman 02-08-05, 03:52 AM	Volume of air will be 1/5th the volume of the bell at the surface. That's never going to be enough for this stunt to succeed. When the OP said bell I was picturing something like "The Mother of Voices" from the movie The Long Ships (one of the coolest Viking movies ever) - there could be a sizeable air pocket in something like that, even at 150', but it would also get saturated with see-oh-two pretty fast (Fort save DC 15 to avoid unconsciousness, -1 cumulative penalty for each round the diver returns to the bell to take a breath), and it would be a :censored: to raise and lower without a substantial winch or a couple of ogres.
The Colonel 02-08-05, 04:52 PM	The usual technique for bell diving was to lower a lead barrel of air parrallel to the bell and release the contents of this into the bell from below to keep the air volume in it under control. Fouling was a problem of course - there is a chemical adsorbent of CO2 which is fairly low tech, but would probably still contstitute metagaming without some serious divinations and a chunky alchemy check to prepare.
Vharuck 02-08-05, 05:52 PM	???? The water that is above the bell is irrelevent. It adds nothing to the weight that has to be lifted. Where did you get the idea that the depth of water above an object has anything to do with how much it takes to lift the object? If the crane on the barge can lift the bell from the pier, it will be able to lift it from the bottom. The only "extra" weight would be the weight of the line used to lower and lift the bell the 150'. AT A little experiment for you: Get a flat sheet of metal that weighs, oh let's say 5 lbs. Punch a hole through the middle and put a rope through it, knotting it so that it stays on the end. Set the metal sheet on the ground. Now lift it. Easy, huh? Barely any work. Set it in a large barrel or something similar. Now, using a couple bags of pet-store gravel for terrariums, cover the plate and fill the inside with all the little pebbles. They'll be our "water." Now, with a good amount of pebbles on it, lift the plate. Harder, huh? That's because the pebbles' weight is the force which gravity pulls them downwards. Since the weight of the pebbles above the plate travels straight down, it's safe to assume that it travels through the plate. Now, by moving the plate in the opposite direction, you have to either pull with a force greater than the weight of the plate and pebbles combined, or engineer a plate so aerodynamic that it can deflect all the pebbles with no effort. Since that's impossible using three dimensions (the width would have to be zero), you engineer something to deflect easier, like say, a bell. However, this does not deflect everything perfectly, as it still feels the resistance of the pebbles. Thanks everybody, once again I'm Bill Nye the Science Guy! (Not really)
Art_Tillary 02-08-05, 09:48 PM	A little experiment for you: Get a flat sheet of metal that weighs, oh let's say 5 lbs. Punch a hole through the middle and put a rope through it, knotting it so that it stays on the end. Set the metal sheet on the ground. Now lift it. Easy, huh? Barely any work. Set it in a large barrel or something similar. Now, using a couple bags of pet-store gravel for terrariums, cover the plate and fill the inside with all the little pebbles. They'll be our "water." Now, with a good amount of pebbles on it, lift the plate. Harder, huh? That's because the pebbles' weight is the force which gravity pulls them downwards. Since the weight of the pebbles above the plate travels straight down, it's safe to assume that it travels through the plate. Now, by moving the plate in the opposite direction, you have to either pull with a force greater than the weight of the plate and pebbles combined, or engineer a plate so aerodynamic that it can deflect all the pebbles with no effort. Since that's impossible using three dimensions (the width would have to be zero), you engineer something to deflect easier, like say, a bell. However, this does not deflect everything perfectly, as it still feels the resistance of the pebbles. Thanks everybody, once again I'm Bill Nye the Science Guy! (Not really) Again, you don't know what you are talking about. I'll try and put this in simple words without violating the CoC. Take your 5 pound plate (no pebbles). Note that has no upright edges, so it is flat. Even it had upright edges, of say an inch like would be needed to hold your pebbles it wouldn't matter. It is what, maybe 10 square feet since sheet metal is fairly thin. Put it in a pool. Lower it to a depth of 2 feet. Weigh it now (by attaching the line to an appropiate scale.) Since water weighs about 64 pounds per cubic foot we have 10 square feet under two feet of water. That is 20 cubic feet of water above the plate. That would be 20 times 64 = 1280 pounds, almost half a ton. Try it, you will find that your plate still pulls the scale to 5 pounds, not to 1280 pounds. AT licensed marine engineer.
Mandarbgrim 02-08-05, 10:13 PM	The water above would require more force to move it aside I am pretty sure..but that it would be hardly significant unless you are moving the bell quickly. Kind of like moving an oar through water isn't it? Hard if you try to do if fast and easy if you do it slowly..and a crane/winch/block type of lifting situation would likely be slow anyways. I could be wrong.
Art_Tillary 02-08-05, 10:36 PM	The water above would require more force to move it aside I am pretty sure..but that it would be hardly significant unless you are moving the bell quickly. Kind of like moving an oar through water isn't it? Hard if you try to do if fast and easy if you do it slowly..and a crane/winch/block type of lifting situation would likely be slow anyways. I could be wrong. Correct. Because it's a liquid it would move aside, plus the height of water is irrelevent. Now, to make the character's live really interesting, can anybody tell me what happens to the ship's center of gravity when they lift the diving bell off the deck? Recommended reference is LaDage's Stability & Trim. AT
aaron3579 02-09-05, 01:56 AM	A little experiment for you: Get a flat sheet of metal that weighs, oh let's say 5 lbs. Punch a hole through the middle and put a rope through it, knotting it so that it stays on the end. Set the metal sheet on the ground. Now lift it. Easy, huh? Barely any work. Set it in a large barrel or something similar. Now, using a couple bags of pet-store gravel for terrariums, cover the plate and fill the inside with all the little pebbles. They'll be our "water." Now, with a good amount of pebbles on it, lift the plate. Harder, huh? That's because the pebbles' weight is the force which gravity pulls them downwards. Since the weight of the pebbles above the plate travels straight down, it's safe to assume that it travels through the plate. Now, by moving the plate in the opposite direction, you have to either pull with a force greater than the weight of the plate and pebbles combined, or engineer a plate so aerodynamic that it can deflect all the pebbles with no effort. Since that's impossible using three dimensions (the width would have to be zero), you engineer something to deflect easier, like say, a bell. However, this does not deflect everything perfectly, as it still feels the resistance of the pebbles. Thanks everybody, once again I'm Bill Nye the Science Guy! (Not really) :rofl: I know I'm being a jerk, but fake intelligence is one of my peeves. Arg. Anyway, I second the notion that this can be a great RPing opportunity.