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Rules for Diving ?


rust

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It seems that I will need some Spot Rules for Diving for my Varun setting, but I am

still undecided how to handle this, and so I would be very interested in your opini-

ons. :)

For Scuba Diving I could use the Swim rules from the BRP core rulebook, perhaps

with the addition that a Fumble includes a risk to get "The Bends" because of a

too fast return to the surface. I am currently thinking of a chance equivalent to

a failed Stamina roll (CON x 5).

Looking at the diving rules from GURPS Transhuman Space - Under Pressure, such

rules could obviously be much more complex (they cover several pages there), but

I doubt that this would really improve the game in my case.

For Hardsuit Diving, I have currently two different types of hardsuits in my setting.

The Mk. I weighs 230 kg, costs 25,000 Credits, has 12 AP and is sufficient for a

depth of 300 meters, the Mk. II weighs 280 kg, costs 40,000 Credits, has 16 AP

and is sufficient for a depth of 600 meters. Both were designed with GURPS and

then converted.

Although both suits are powered, I think they should reduce the DEX based skills of

the diver wearing them, but I am not sure about the size of the penalty. Currently I

tend towards -10 % for the Mk. I and -20 % for the Mk. II.

The next problem would be the Fumble for Hardsuit Diving. In my view it should be

a very serious equipment failure, something that would kill the diver unless he is

saved by his "buddy" (divers in my setting never dive alone), with the "buddy" ha-

ving to succeed in either a Repair (Marine Systems) or Hardsuit Diving roll, what-

ever is his better skill.

Well, that are my thoughts so far. What do you think ?

Thank you. :)

"Mind like parachute, function only when open."

(Charlie Chan)

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It seems to me that underwater adventure will be something of a feature for this setting. In that case I would say that it deserves a little more punch than simply using the swim skill. There's a lot more to scuba diving than just swimming, so I would suggest a Deep Sea Diving skill that covered both at the very least, and you might divide it into SCUBA DIVING (covering both wet suit and dry suit) and POWERED HARD SUIT DIVING, depending on how you think the skills might be used.

I would allow any kind of Diving skill to be substituted for swim skill in situations where swim is called for, but not the other way around. If would limit people's underwater activities to their Dive skill in the same way the doing something while riding is limited to one's ride skill.

For fumbles, I would make a separate Diving Mishap Table with maybe 10 items on it - probably one for SCUBA and another for hardsuit.The Scuba list might include things like Nitrogen Narcosis, Cut or pinched air line, Octopus malfunction, Regulator malfunction, Mask gets knocked off, cut self on equipment or sea floor, disoriented/compass fails, depth guage fails (which can be really bad news if your down deep), dropped tool, and Major Mishap (which would depend on the situation, but could include surfacing too fast, or a rip in the buoyancy compensator), etc.. For harsuits I would use some of the same (dropped tool, disoriented, depth guage fails), but not others (mask knocked off, cut line, regulator fail), and I would add some new ones (loss of pressure control, loss of motor control, view panel obscured, and so on) .

Thalaba

"Tell me what you found, not what you lost" Mesopotamian proverb

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Thank you very much for your ideas.:)

It seems to me that underwater adventure will be something of a feature for this setting. In that case I would say that it deserves a little more punch than simply using the swim skill. There's a lot more to scuba diving than just swimming ...

I agree, but in my setting scuba diving will be somewhat rare, because the colony's facilities are about

200 meters below the ocean surface, which makes hardsuit diving the far more common form of diving.

Therefore I am uncertain whether very detailed rules for scuba diving really are a good idea.

For fumbles, I would make a separate Diving Mishap Table with maybe 10 items on it ...

A very good idea. ;D

"Mind like parachute, function only when open."

(Charlie Chan)

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Because of your equipment suggestions I have started working on diving rules for possible inclusion in MODERN EQUIPMENT CATALOG Volume 2. Won't see the book until the end of the year at best so that does not help now. I am not inclined to use skill rolls for environmental affects, as can be seen in the Altitude Sickness rules in MEC, so the chances of getting "the bends" will be based off CON rolls for exceeding safe ascent rates. Skill roll fumbles will typically be reserved for equipment failures, or more likely the failure of the character to correctly use equipment.

For a sci-fi hard suit you have to consider that the interior pressure would very likely be kept at surface pressure levels, which would negate the need for ascent rate restrictions or risk of the bends. Of course, if there is a breach for some reason then it is squishy time and no skill roll is going to help. As your suits are powered, maybe the base DEX penalty should be a little lower, say -5/-10, but greatly increased for tasks involving "fine manual dexterity", or increase the Difficulty of the roll.

Breathing medium and depth of dive are another factor. Wrong mix, or equipment, at the the wrong depth and serious problems result. Probably be easiest if this aspect has been dealt with in your setting. I am still a long ways from having rules for this yet.

hope that helps

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hope that helps

Thank you very much, it helps a lot. :)

Reading through the many good ideas on this thread:

- the risk for The Bends while scuba diving will be based on CON and not connected to the skill roll,

- a Fumble with scuba or hardsuit diving will lead to a result on a mishap table,

- the DEX penalty for the hardsuits will be reduced to -5 % / - 10 %.

Yep, thank you all, now I have an idea how to handle this. :thumb:

"Mind like parachute, function only when open."

(Charlie Chan)

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I am not inclined to use skill rolls for environmental affects, as can be seen in the Altitude Sickness rules in MEC, so the chances of getting "the bends" will be based off CON rolls for exceeding safe ascent rates. Skill roll fumbles will typically be reserved for equipment failures, or more likely the failure of the character to correctly use equipment.

I'm not so sure that's a good idea. First off getting the bends (decompression sickness) is due to staying too deep for too long, or ascending too quickly, and is a factor of skill rather than CON. Someone with a high skill, would not the proper procedures and be able to work out the right time at depth. Someone who is just healthy is any less likely to get the bends.He might be better able to survive the experience, but that is something else.

Chaos stalks my world, but she's a big girl and can take of herself.

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I have meanwhile decided to use most of the CoC rules for scuba diving

that Atgxtg mentioned (thank you again :)).

They include a skill roll for the safe return to the surface, and I think that

a Fumble with this roll could force the diver to make a Stamina roll or suffer

from The Bends.

This could consider both the fact that he needs some diving skill to know

how to handle desompression and the fact that someone with a higher

CON is less likely to suffer severe damage from The Bends.

"Mind like parachute, function only when open."

(Charlie Chan)

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I'm not so sure that's a good idea. First off getting the bends (decompression sickness) is due to staying too deep for too long, or ascending too quickly, and is a factor of skill rather than CON. Someone with a high skill, would not the proper procedures and be able to work out the right time at depth. Someone who is just healthy is any less likely to get the bends.He might be better able to survive the experience, but that is something else.

Yes, successful swim rolls will keep the character safe from DCS, but a character can fail dozens of swim rolls and never risk DCS if the situation is not correct. Fumble a swim roll and get DCS just does not cut it. Fail a Swim roll while ascending and there is trouble, move on to DCS roll. In situations like this I don't require a fumble roll for the brown stuff to hit the fan, but there again I am probably working outside the norm.

Use of a CON roll is a tough choice for DCS effects. Honestly, I would prefer a straight percentage roll, but roleplayers seem to prefer some variability and I find a stat better then a skill which really has no impact on phsiological outcome. With DCS there is a huge range of results and onset times and some sort of roll is needed. The steriotypical collapsing unconscious upon breaking the surface of the water is a very unlikely result of DCS. Being a good diver is of no use for this roll.

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My current idea of the consequences of a failed Stamina roll after a fumbled

Diving skill roll for the return to the surface would be a time limit to take the

diver to a medical facility with a decompression chamber, for example the 2 D6

hours used in the Call of Cthulhu rules.

"Mind like parachute, function only when open."

(Charlie Chan)

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Yes, successful swim rolls will keep the character safe from DCS, but a character can fail dozens of swim rolls and never risk DCS if the situation is not correct. Fumble a swim roll and get DCS just does not cut it. Fail a Swim roll while ascending and there is trouble, move on to DCS roll. In situations like this I don't require a fumble roll for the brown stuff to hit the fan, but there again I am probably working outside the norm.

Yeah. What CoC did was list the reasons for the roll. So going to differnert depths and back required SCUBA rolls, with the risk of DCS. Other reasons for a Swim/SCUBA roll didn't necessarily result in DCS.

Oh and CoC did use a SCUBA skill for this, not swim.

Use of a CON roll is a tough choice for DCS effects. Honestly, I would prefer a straight percentage roll, but roleplayers seem to prefer some variability and I find a stat better then a skill which really has no impact on phsiological outcome. With DCS there is a huge range of results and onset times and some sort of roll is needed. The steriotypical collapsing unconscious upon breaking the surface of the water is a very unlikely result of DCS. Being a good diver is of no use for this roll.

Fair enough. In CoC DSC was automatic if divers didn't spend the required time at depth on the way back (like say if they got spooked by a deep one or great white shark). They had to be sent to away for medical aid or die.

What you could do it treat DCS like a poison (nitrogen poisoning!), with a delayed effect. Perhaps every hour the character must roll against the poison. or lose 2HP. Success only losses 1. The POT could be the duration (in hours). Just brainstorming here.

I suspect rust's colonists have enough brains to have decompression chambers, and possibly a hi-tech medical method of removing the excess nitrogen from the bloodstream quickly and safely.

Hmm, to be honest, I'm surprised the colonists don't make their colony a little more buoyant. At 10-25m or so they could avoid all that nastiness. Lower a pressuring diving bell, elevator to work crews on the bottom (or send down robots). But then, if they were sane, they wouldn't be colonists.

Edited by Atgxtg

Chaos stalks my world, but she's a big girl and can take of herself.

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What about 2d6-2 just for the chance of that cinematic loosing consciousness just before breaking the surface? It does not happen often but it would make for a good "Oh crap" moment.

The 2D6 roll, as listed is just how long you have to transport the guy to a medical facility before he dies. It has nothing to do with what state he is in during that time. With all the lovely symptoms that goes with DCS, our lucky diver may have several "oh crap" moments and might indeed have to make a roll (CON?) to avoid losing consciousness.

Cosniding what's in store for him, he might very well wish to pass out and avoid some of the pain and suffering.

Chaos stalks my world, but she's a big girl and can take of herself.

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CoC seems to have a very lethal and unrealistic take on DCS.

Yeah. Somewhat. In a nutshell, if you get DCS, it's fatal unless they get you to a decompression tank. End of story. Where you've been down to 80 feet for 2 minutes or 130 feet for 2 hours makes no difference as far as the effects go. The 80 foot dive is safer, and has fewer penalties, but get DCS and it pretty much an autokill.

I suspect that in CoC, it doesn't matter mch, since characters are rarely lucky enough to die from something as ordinary as DCS.

In the real world symptoms might not even show up for several days.

Edited by Atgxtg

Chaos stalks my world, but she's a big girl and can take of herself.

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In a nutshell, if you get DCS, it's fatal unless they get you to a decompression tank. End of story.

Sorry, but that is completely false. Recompression is the recommended treatment for Type 1 DCS simply beacause of the risk that symptoms and pain are covering the symptoms of the more serious Type 2 or AGE. Even with Type 2 death is not certain without recompression. It is possible for nitrogen bubbles to migrate and DCS to worsen even hours after the dive (especially with physical activity or alcohol consumption), another reason for continued evaluation and recompression for even mild symptons. 100% oxygen is very good at lessening symptoms of Type 1 DCS.

DAN (Diver's Alert Network) only publishes studies involving recommended treatment, 100% oxygen followed by recompression, so there are no statistical studies on survival without treatment (that I am aware of), but if you read the reports on the early caison workers you will see the full range of DCS symptoms and generally surviving. Many are the reports of workers coming to the surface dizzy and with joint pain, suffering through the night and looking forward to going down the next day because the mysterious malody symptoms went away. Death rates only skyrocket as technology improved which resulted in deeper and longer working hours. the nitrogen bubbles that are the cause of DCS (and AGE) will disolve naturally given time.

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Hmm, to be honest, I'm surprised the colonists don't make their colony a little more buoyant. At 10-25m or so they could avoid all that nastiness. Lower a pressuring diving bell, elevator to work crews on the bottom (or send down robots). But then, if they were sane, they wouldn't be colonists.

The reason is the weather. On a planet without continents to slow down and weaken

hurricanes, storms can get both very common and quite powerful, and the surface

region of the ocean - down to several dozen meters - is not a good place to be du-

ring such a storm. Besides, with aquaculture, mining and most other activities happe-

ning on the seafloor, it seems logical to have the habitat nearby, especially since a

seafloor habitat also has the advantage to keep the most vital and dangerous parts,

like the fission reactor, safe underground.

As for decompression, I see the colonists' scuba gear as including sophisticated com-

puters, HUDs for their face masks and short range sonar communicators, so that the

diving computer can warn a diver with both acoustic and visual signals whenever he

returns to the surface too fast.

Therefore a mistake on the way back to the surface should be rare, the result of an

equipment malfunction or a really serious diver problem, for example panic. So in my

view a fumbled skill roll is a good way to simulate this, while a failure would mean a

comparatively minor problem only - for example the lost tool Thalaba mentioned.

I think that decompression sickness should be painful and disabling, but not lethal,

given the medical equipment of the setting. Oxygen will be available wherever divers

work, and a decompression chamber usually not very far away.

I like the 2D6-2 to give the diver a "chance" for a cinematic collapse. And I think I

will use the result of the failed stamina roll as the number of days the character has

to spend under medical supervision (e.g. at the hospital), with each point the roll

is missed by as one day in hospital, and if he is not delivered to the hospital in time

(during the 2D6-2 hours) the number of days at the hospital are doubled.

"Mind like parachute, function only when open."

(Charlie Chan)

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So my idea for a Diving Spot Rule for my setting now looks like this:

A diver has to make a skill roll at the beginning and at the end of each dive.

Additional skill rolls during the dive depend on the specific situation. Scuba

divers use the Swim skill, hardsuit divers use the Hardsuit Diving skill.

A Failure always leads to a result on the Diving Mishap Table.[and forces the

diver to end the dive and to return to the surface - deleted.] Other conse-

quences of a Failure depend on the specific situation.

A Fumble always leads to a dangerous and potentially lethal result from the

Diving Mishap Table. The problem can only be solved with the help of another

diver, who has to succeed with a skill roll, for example Hardsuit Diving or Re-

pair (Marine Systems). A Fumble makes additional dives on the same day im-

possible. Other consequences of a Fumble depend on the specific situation.

A Fumble at the end of a scuba dive results in the risk of decompression sick-

ness. The diver has to succeed with a Stamina roll or has to receive medical

care within 2D6-2 hours. If the diver arrives at the hospital in time, he will

have to stay there for a number of days equivalent to the number of points

by which he missed his Stamina roll. If the diver does not arrive at the hospi-

tal in time, the number of days he has to stay at the hospital is doubled.

Edited by rust

"Mind like parachute, function only when open."

(Charlie Chan)

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Sorry, but that is completely false.

Yes, I know. I was just quoting how it works in CoC: The Bermuda Triangle. Like I posted earlier, in the real world, a diver might not even being showing symptoms for several days. I also think the diving penalties might be a bit high, as well.

Chaos stalks my world, but she's a big girl and can take of herself.

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So my idea for a Diving Spot Rule for my setting now looks like this:

A Failure always leads to a result on the Diving Mishap Table and forces the

diver to end the dive and to return to the surface. Other consequences of a

Failure depend on the specific situation.

Considering how often even experts fail a roll in BRP, maybe a simple failure shouldn't be so bad as to end the dive. When I watch divers on TV, something always breaks, but the divers can access the situation and usually continue on with the dive. Most "failures" that I see are little annoyances that are more of a obstacle or hindrance than a mission ended.

Maybe you could put things on the table like "loose your knife", "ballast falls off -10% to skill", "a fish gets curious and starts following you", "flipper fell off, try grabbing it before it floats away", "do something stupid, dolphins laughing at you, again", or "mask fogged up, vision impaired until cleared."

Chaos stalks my world, but she's a big girl and can take of herself.

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Considering how often even experts fail a roll in BRP, maybe a simple failure shouldn't be so bad as to end the dive.

True, and I am not yet sure how to handle this.

The scuba divers in my setting all have rather high skill levels, because they get a 20 % cultural skill

bonus to their Swim skill, which makes 45 % the lowest possible Swim skill for a Varunian, and for the

professional hardsuit divers with their high tech equipment most routine tasks should be Easy, which

would also give them a very good skill value for normal operations. Both should make failures compa-

ratively rare.

I think I will have to playtest this and see how often failures really happen, and then modify the rule

if it seems appropriate.

"Mind like parachute, function only when open."

(Charlie Chan)

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True, and I am not yet sure how to handle this.

It just a question of mathematics. Even with 100%+ skill, a character in BRP will still fail 5% of the time (96-00). If all failures were serious ones, 5% of all take offs and landings would fail. driving to work would be sucicidal, and most arms manufactures would be sued out of existence.

Assuming that your players are going to be making a lot of swim/SCUBA/Hardsuit skill rolls while interacting with the environment, the mathematically effects of mutiple rolls will make it very difficult for any mission to succeed.

For example, lets' say a group of 4 PCs got to leave the colony, do some work, and return. They each have a a modfied skill over 100%, and the GM says that they need to make three "Dive rolls" each.

At a 95% success chance per roll (the best possible in BRP), each diver has only a 86% chance of being successful. With 4 PCs the odds drop down to 54%. So nearly half the mission will fail. And that's with the best possible divers. Drop down to mere "experts" with 75% skill, and the chances of success are down to about 3% .

Unless the colony's profit margin is obscenely high, it would quickly fail and the settlement abandoned.

So I think you are either going to have to cut down on the rolling, or on the consequences for failure. Personally, I'd probably limit "scrub the mission" type failures to fumbles, and assume failures just mean some sort of minor problem. Like a guy wastes a few minutes adjusting his suit, the hatch gets stuck, he gets disoriented, the stupid light doesn't work right and so forth.

Chaos stalks my world, but she's a big girl and can take of herself.

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It just a question of mathematics.

Ah, you know, mathematics and me was never a love affair ... :o

But you are obviously right, so the sentence about having to end the dive

after a failed skill roll will be deleted. :)

"Mind like parachute, function only when open."

(Charlie Chan)

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Perhaps a failed roll means the task takes longer. The more failures the higher the chance that the diver runs out of oxygen/power/whatever or might encounter some nasty critter.

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Perhaps a failed roll means the task takes longer. The more failures the higher the chance that the diver runs out of oxygen/power/whatever or might encounter some nasty critter.

Thank you, a good idea - it could become the main entry of the Diving Mishap Table.

If I use a bell curve like 2 D6 for the table and make it entry number 7, it would be

the "standard problem" caused by a failure, with other and more serious problems

somewhat less likely. :)

"Mind like parachute, function only when open."

(Charlie Chan)

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