Underwater Combat Rules: what did I miss?

BASH MAN · Post by **BASH MAN** » Sun Oct 01, 2006 6:55 am

Hello, this is Chris Rutkowsky. As some of you may know, I work for Goodman Games, converting their fantastic Dungeon Crawl Classics products for use with C&C. Currently, I am working on a module that involves underwater combat, and because there is no CKG at present time, I am adding my own interpretation (based on AD&D rules) of how it should work. I would like your feedback on what I have so far. (PS, I cannot get on the CKG boards anymore, since we switched to the new boards, I would appreciate the "official rules" regarding underwater combat)
Underwater Combat

In summary, be aware of the following: Be sure to keep track of what light source the PCs are using to see (their torches wont work). Additionally, only thrusting weapons will do normal damage underwater, unless the character has some sort of freedom of movement ability.

Ranged and thrown weapons are useless underwater, except specially made crossbows, and those have half the range, and netswhich have a range of 1 per point of the throwers strength (assume 10 range for monsters, +1 per HD).

Spells also work differently underwater. Magical fire spells will not function at all (there is no oxygen to fuel the fire), and electrical spells will function differently. A lightning bolt will burst the same as a fireball at its point of origin, instead of striking in a line. Similarly, shocking grasp will affect an area as a burning hands spell. Note that heat metal will function normallyit does not use fire, but actually just heats the metal, which also begins turning the water in the targets area into steam, obscuring the targets vision (giving a -1 penalty to hit and AC), in addition to the damage.

Chill Metal does no damage underwater, however, it does make the target more buoyant as ice forms on the metal. On armor, this would give a penalty of -5 feet to swim in any direction other than straight up. On an item held in the hand the target must make a STR check or the item floats to the surface, and a weapon will become useless in this sheath of blunt and buoyant ice.
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Treebore · Post by **Treebore** » Sun Oct 01, 2006 4:15 pm

Looks like you got the basics covered. The only thng I can suggest is to look at the 3E SRD on underwater combat to make sure you have ALL the basics covered.

Plus I am sure Serleran will know a thing or two. Or five.

serleran · Post by **serleran** » Mon Oct 02, 2006 1:28 pm

Quote:
Ranged and thrown weapons are useless underwater, except specially made crossbows, and those have half the range, and netswhich have a range of 1 per point of the throwers strength (assume 10 range for monsters, +1 per HD).

I have to disagree here. Crossbows, if made properly, perhaps... however, many throwing weapons such as javelins, spears, tridents, forks, and other classic "underwater" weapons should work as normal. In addition, bludgeoning and slashing weapons, ie, anything that is not a pokey weapon like a rapier or dagger, should have a penalty to hit, and should inflict less damage as well, due to the great difficulty in swinging them with muscle power when fully submerged. I personally would recommend the "non-proficient" penalty, which is always -5, and for damage, drop the die by one type, so that, for example, a two-handed sword goes from 2d6 to 2d4, and a d8 drops to d6 (perhaps a chart would be most effective for those who don't understand what a lowered die is.) Also, one other thing that is crucial is amount of time a PC can remain underwater. I suggest Con / 6 + Con modifier in minutes before drowning begins. Those with the "hold breath" ability, a la lizardman would follow the rules for that, instead. Monsters with a swim speed cannot be drowned as they are assumed to be semi-aquatic. Other monsters, like a kobold, would be able to hold its breath a number of minutes equal to HD, so a kobold, for example, would be 1 minute (6 rounds).

Last thing: to my knowledge, as of this post, there are no official underwater combat rules... so, they need to be created, and what is here is a good foundation. If you want into the CKG forum, email Steve and ask for it, being sure to include your username.

BASH MAN · Post by **BASH MAN** » Tue Oct 03, 2006 12:55 am

Okay Serl, will do.

Regarding the thrown weapons underwater, I can kind of see your point, however, the underwater environment creates a lot of "drag" on any projectile. The reason that spears could be effective underwater is because they are propelled by a device that is stronger, and more efficient for that environment (a rubberband and a tube, or compressed air propulsion). However, medieval spears would be hard to throw with just your arm underwater. it takes a mechanical device to propel the spear (or crossbow bolt) with the necessary force. Try throwing a spear (or a broom handle, etc) in the deep end of the swimming pool and you can see what I mean.

However, I guess a piercing hurled projectile with a long shaft could be thrown at a reduced range. The range would be 1' per point of damage you do with it (which means you need to roll damage when you throw it. If you roll lower than the distance, your weapon never got there! Each foot the weapon travels reduces its damage on impact by 1 point. So you could fire a bow underwater, but the arrow is only going to move 1d8 feet (drag is too strong).

You cannot throw knives or axes effectively (too much drag). Slings are also impossible.

I guess having slashing and bashing weapons do automatic minimum damage underwater would be a fair fix for them. Remember that underwater, the best weapons are spears, tridents, and daggers. A character who relies soley on an axe, bow, or sword, will have problems. .
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serleran · Post by **serleran** » Tue Oct 03, 2006 1:45 am

Yeah, fighting underwater is akin to fighting inside an ooze... if one can pierce the outer shell, one can fight effectively, but if completely submerged... well, you're basically screwed.

Minimum damage for other weapon type (ie, not piercing) is a good idea, and better than what I suggested as it more directly implies the fact that swinging such a weapon should be very difficult, if not impossible.

Oh, and one other thing: the freedom of movement spell should cancel all associated downsides for underwater combat for whomever is affected. It does not, however, allow one to breathe underwater.

BASH MAN · Post by **BASH MAN** » Thu Oct 05, 2006 6:15 pm

This is for an underwater dungeon section, so I dont think breathholding will be an issue-- if they PCs cannot breath underwater, they cannot get to this place. however, that does bring a really devious idea to mind-- have an enemy cast dispell magic so their waterbreathing goes away!
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Treebore · Post by **Treebore** » Thu Oct 05, 2006 6:47 pm

I actually expected to be wrong, and I was right. Definitely more than 5. 8)

serleran · Post by **serleran** » Fri Oct 06, 2006 2:11 am

Is that a bad thing?

Sorry. I'll try to not come across as a "know-it-all." I don't mean to.

Treebore · Post by **Treebore** » Fri Oct 06, 2006 2:27 am

No, you impress me with everything you remember and how quickly you rationilze/logic ideas out into workable form. Plus that you have the motivation to write so much of it out.

BASH MAN · Post by **BASH MAN** » Wed Oct 11, 2006 8:33 am

So here are my thoughts on breath holding.

If you have CON prime, you can hold your breath 1 round per point of CON, when you are sitting still and not exerting yourself. Doing this is extremely strenuous in and of itself.

If CON is not prime, you can hold your breath 1 round per 2 points of CON when not exerting yourself.

If you are exerting yourself-- swimming, fighting, etc, underwater, the length of time you hold your breath rapidly diminishes. A character with CON prime can hold their breath 1 round per 2 points of CON while being active.

A character without CON prime can hold their breath 1 round per 4 points of CON while exerting himself.

This use of Primes is like the difference between Navy Seals and some guy on the street fighting underwater. The seal will win just by pulling the other guy under, because he can hold his breath longer!

For monsters, and special abilities that allow characters to hold their breath longer, just multiply this duration. So a lizardman could hold its breath 4 times these durations.

What happens when you cannot hold your breath anymore? You begin to drown. Drowning does not kill you slower because you are a high level character! Being high level meant you had a better chance not to get into this situation!

Every round you are drowning, Make a CON save, with the CL equal to your character level (thus, your level will not help you). If you succeed, you take 1d2 CON damage. If you fail, you take 1d4+1 CON damage and 1 point of permanent INT damage (brain damage). If either CON or INT drop to 0 in this manner, you are dead.
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johns · Post by **johns** » Wed Oct 11, 2006 2:32 pm

Are tridents actually good for fighting underwater? I know they're used for catching fish, but that just involves somebody above water sticking the fork into the water. The value of the trident is that three prongs hold onto a fish better than one prong (a spear).

BASH MAN · Post by **BASH MAN** » Wed Oct 11, 2006 11:49 pm

johns wrote:
Are tridents actually good for fighting underwater? I know they're used for catching fish, but that just involves somebody above water sticking the fork into the water. The value of the trident is that three prongs hold onto a fish better than one prong (a spear).

Because it is a piercing weapon, yes, a trident is a useful weapon underwater. It is no more effective than a spear by game mechanics of C&C. However, as it would be used by gladiators, etc, it was not just useful for stabbing, but you could catch and break an opponent's weapon with the prongs.
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Nelzie · Post by **Nelzie** » Thu Oct 12, 2006 1:32 am

BASH MAN wrote:
However, as it would be used by gladiators, etc, it was not just useful for stabbing, but you could catch and break an opponent's weapon with the prongs.

There should be some some bonus when using a Trident in conjunction with either a dex or str SIEGE check to break weapons. How about a +2 to break an enemies weapon with a weapon that is designed for weapon breaking?

Of course, should the weapon then receive a saving throw of some sort? Would magical weapons receive a much greater bonus to the save due to their relative rareness?
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johns · Post by **johns** » Thu Oct 12, 2006 3:05 pm

I only ask because it is a piercing weapon with a cross-bar, which I would think would add some drag, while a spear has no such problem.

Generally, I like to keep things simple, so I would agree to just make all piercing weapons work the same.

serleran · Post by **serleran** » Thu Oct 12, 2006 3:27 pm

If you want to use a trident as a weapon-breaker, I'd suggest making the rules for such slightly different, as per the mancatcher for example. The way I'd do it, as an initial thought, would be:

If you've attacked with the weapon, you suffer a -4 penalty to any defensive action with the weapon. Otherwise, it can be used to parry, by making an attack roll against the BtH of the opponent, with magical modifiers and weapon specialization applied (not Dexterity or Strength). If the attack is successful, the weapon is pinned, and may be broken if it fails a save (treat the weapon as having to roll a 12 or higher on d20.) A weapon made of durable material such as adamantine or mithril gains a +10 bonus to resist being destroyed. Parrying in this way can be done once / round.

BASH MAN · Post by **BASH MAN** » Fri Jun 15, 2007 7:10 am

johns wrote:
I only ask because it is a piercing weapon with a cross-bar, which I would think would add some drag, while a spear has no such problem.

Generally, I like to keep things simple, so I would agree to just make all piercing weapons work the same.

Ah, but Tridents are a good weapon because of the prongs. You see, underwater, (especially from the surface) it is hard to see what you are aiming at. Having those extra prongs was a way of counter-acting worsened visibility due to water refraction [from the surface at least. people did not go diving with tridents underwater]
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CharlieRock · Post by **CharlieRock** » Fri Oct 05, 2007 5:20 pm

BASH MAN wrote:
So here are my thoughts on breath holding.

If you have CON prime, you can hold your breath 1 round per point of CON, when you are sitting still and not exerting yourself. Doing this is extremely strenuous in and of itself.

If CON is not prime, you can hold your breath 1 round per 2 points of CON when not exerting yourself.

If you are exerting yourself-- swimming, fighting, etc, underwater, the length of time you hold your breath rapidly diminishes. A character with CON prime can hold their breath 1 round per 2 points of CON while being active.

A character without CON prime can hold their breath 1 round per 4 points of CON while exerting himself.

This use of Primes is like the difference between Navy Seals and some guy on the street fighting underwater. The seal will win just by pulling the other guy under, because he can hold his breath longer!

For monsters, and special abilities that allow characters to hold their breath longer, just multiply this duration. So a lizardman could hold its breath 4 times these durations.

What happens when you cannot hold your breath anymore? You begin to drown. Drowning does not kill you slower because you are a high level character! Being high level meant you had a better chance not to get into this situation!

Every round you are drowning, Make a CON save, with the CL equal to your character level (thus, your level will not help you). If you succeed, you take 1d2 CON damage. If you fail, you take 1d4+1 CON damage and 1 point of permanent INT damage (brain damage). If either CON or INT drop to 0 in this manner, you are dead.

This is exactly what I was looking for. Thanks BashMan and Serleran.

So, basically you have a 'breath pool'. The number of points in the breath pool equal your Con. If CON is your prime and you are doing nothing that round, you spend one point from the breath pool. If CON is not your prime, or you choose to do an action (swimming, fighting, struggling free from chains, etc.) you spend two points from the breath pool. If CON is not your prime, and you try an action, you spend four points from your breath pool.

After all your breath pool points are gone, you can start drowning.
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Steerpike · Post by **Steerpike** » Tue Aug 04, 2009 11:41 pm

CharlieRock wrote:
This is exactly what I was looking for. Thanks BashMan and Serleran.

So, basically you have a 'breath pool'. The number of points in the breath pool equal your Con. If CON is your prime and you are doing nothing that round, you spend one point from the breath pool. If CON is not your prime, or you choose to do an action (swimming, fighting, struggling free from chains, etc.) you spend two points from the breath pool. If CON is not your prime, and you try an action, you spend four points from your breath pool.

After all your breath pool points are gone, you can start drowning.

I like all of this except the drowning part at the end, because CON is already "used up" if you will, determining how long you can breathe, it doesn't seem right to apply drowning damage to CON as well. The CON difference among PCs has already been factored in previously.

I think I'd use what you have above, and then say when you can no longer hold your breath you have to make a CON save with CL equal to level, and the CL increases by one each subsequent round. The first miss renders the PC unconcious. The second miss and the PC starts dying, and on the third missed CON save the PC is dead.

I do like the permanent INT damage though. Have to think on that.
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Steerpike · Post by **Steerpike** » Wed Aug 05, 2009 12:23 am

So here's something else I'm thinking:

PCs wearing 15 lbs or less in terms of armor suffer a -2 to their AC due to reduced dexterity underwater.

PCs wearing between 15 and 30 lbs of armor suffer a -4 to AC.

PCs wearing more than 30 lbs of armor suffer a -6.

What do you think? Too harsh? I'm thinking of it in terms of reduced dexterity, not a reduced effectiveness of the armor. Just that a guy in plate mail trying to fight under water is going to have a tough time.
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Relaxo · Post by **Relaxo** » Wed Aug 05, 2009 1:48 am

havn't read the thread but wanted ot say hi!

For me, only crossbows would work underwater for missles, and probably only at short range.

csperkins1970 · Post by **csperkins1970** » Wed Aug 05, 2009 5:39 pm

I wouldn't have armor weight or encumbrance give any additional penalties underwater because all land-dwellers are gonna have a tough time swinging weapons and maneuvering underwater. Due to that I'd assign a flat, -2 penalty, to all non-piercing weapon attacks/damage and to AC. I'd also cut movement by 3/4, as moving underwater is extremely tough due to the fact that one's natural buoyancy works against their ability to move.
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