Combat (and other activity) Underwater

[Trachmyr]

GURPS AQUATICS, Part 4c (Rules)

Swimming and Fatigue
	Swimming at top speed, requires a swimming roll every 15 seconds to avoid the loss of 1 FP. Paced swimming requires a roll every minute, and speed is exactly ½ of water move. Increase the fatigue cost to 2 FP for a failed HT roll if swimming completely underwater. For long distance swimming, roll HT every 30 minutes, losing 2 fatigue per encumbrance level on a success. If simply treading water, lose only 1 fatigue per encumbrance level on a success. If swimming fully underwater, increase base fatigue loss by +1 fatigue per encumbrance level. A failed HT roll indicates a loss of twice the given fatigue! 
	Distance traveled under ideal conditions for long distance swimming is Water Move x 0.4 miles (or Move x 0.5 miles on a successful Long-Distance Swimming skill roll). Apply normal modifiers for build and apply encumbrance level as a penalty. Those with the Very Fit Advantage take one-half of the normal fatigue loss (round up), or roll versus HT for fatigue loss at twice the normal interval if possible. 
	When calculating long distance travel, treat calm waters as Average Terrain (x 1.0), moderate waters as Bad terrain (x 0.5), and rough waters as Very Bad Terrain (x 0.2). Swimming underwater can avoid weather effects but requires either Breath Holding at level 5+ or the Doesn’t Breath Advantage (including Oxygen Storage), and is considered to be Bad terrain. In moderate waters, strong currents (like the Gulf Stream) can cause a change in the terrain modifier to Average if swimming with the current, or to Very Bad if swimming against the current. 
	Aquatic and Amphibious creatures may substitute a basic HT roll for any swimming roll. If normally allowed to ignore underwater penalties, they do not suffer increased fatigue loss for swimming underwater (sprinting, paced or long-distance), nor do they suffer any fatigue loss for simply treading water, instead they may count that time as resting. They may add their sprinting bonus to both top speed and paced swimming. Lastly, they may make a roll against Long Distance Swimming to increase their long distance movement by 25%, and may enjoy bonuses to their HT (or swimming) rolls to versus fatigue from Long-Distance swimming. A skill of HT level gives a +1 bonus, a skill level of HT+1 gives a +2 bonus.

[Trachmyr]

GURPS AQUATICS, Part 5 (Weapons)

Melee Weapons Underwater
	Weapon use underwater is hampered by the increased drag of the environment, and receive penalties to attack rolls and damage based upon the weapon’s Drag Level. These penalties are in addition to any other penalties for fighting underwater (i.e., Underwater Penalties, Vision Penalties, etc.). Always calculate Drag penalties using a weapons longest reach for that attack mode, not simply the reach at which it’s being wielded. Many weapons will have different Drag Levels and penalties depending on how it is used, some swords, most polearms and even knives fall into this category. Remember to use the correct Drag penalties for the mode of attack being used.
	A weapon is by default considered to have “Medium Drag”, this gives a -2 penalty to hit if reach 1, plus an additional -4 to hit for each extra yard of reach. There is no additional penalty to hit in close combat, other than normal close combat penalties. Damage from a Medium Drag weapon is only half the damage rolled. If you are fighting in the water, but not completely underwater (at the surface), the penalties are halved and damage is 2/3 the rolled amount.
	“High Drag” weapons are swung weapons that have a U in the parry column, or any weapon with an unusually wide shape (e.g., Shields, and many improvised weapons). These weapons are at a -2 penalty to hit in close combat (in addition to normal close combat penalties), -4 penalty to hit if reach 1, plus an additional -4 to hit for each extra yard of reach. Damage from a High Drag weapon is only 1/3 of the damage rolled. If you are fighting in the water, but not completely underwater (at the surface), the penalties are halved and damage is half of the rolled amount.
	“Low Drag” weapons are thrusting weapons that are either Impaling or have a narrow crushing surface (e.g., Spears, Knives, Staffs, Swords - sharpened or blunt). These weapons are at a -2 penalty to hit if reach 1, plus an additional -2 to hit for each extra yard of reach. There is no additional penalty to hit in close combat, other than normal close combat penalties. Damage from a Low Drag weapon is 2/3 of the damage rolled. If you are fighting in the water, but not completely underwater (at the surface), the penalties are halved and damage is only a -1 penalty to the rolled amount.
	Amphibious and Aquatic creatures that are allowed to ignore normal underwater penalties, also use weapons more efficiently underwater. They use penalties to hit as if they were not completely underwater, that is to say half normal penalties. When using a weapon in Close Combat, the damage is reduced as if they were not completely underwater. If an Amphibious or Aquatic creature happens to actually be not completely underwater while fighting, the benefits listed here are not cumulative.

Unarmed Combat Underwater
	Unarmed combat follows the same rules as for Melee Weapon with the exceptions that Grappling and Bites never have additional penalties beyond normal underwater penalties, and always do full damage. All thrust-based unarmed attacks with a reach of “C” (e.g., Punches, Knee Strikes, Short Strikers) are considered “Low Drag”. All other thrust-based unarmed attacks (including kicks) and all swing-based attacks (I.e., Roundhouse Punch) are “Medium Drag”. There are no “High Drag” unarmed attacks.

Thrown Weapons Underwater
	Thrown weapons use the same rules as for Melee weapon, including attack penalty and damage reduction, but treat their reach as “C” if bulk is -2 or less, adding 1 reach for each additional -2 Bulk (or fraction thereof). Weapons that are thrown ‘end over end’ (like knives and axes), can be Medium Drag at best. Certain weapons: Bolas, Cloaks, Lassos, Slings and Spear Throwers are always “Heavy Drag”.
	Low Drag weapons have only 1/5th normal ½D and Maximum ranges, Medium Drag weapons have 1/10th normal ½D and Maximum ranges, while High Drag weapons have 1/20th normal ½D and Maximum ranges. If a thrown weapon is used above the water, regardless of the weapon’s actual Drag Level, reduce range to 2/3 normal, attack penalties to -1 per “reach” and weapon damage to just a -1 to the rolled amount. Always round ½D ranges down (to a minimum of 2), but Max ranges up (also to a minimum of 2).
	When Throwing something underwater, the GM will have to decide on the “Drag Level” of the object, although most items are “Medium Drag”, or “Heavy Drag” if wide or requires a swing motion. Apply range, attack and damage penalties as normal for thrown weapons used underwater.

Other Ranged Weapons Underwater
	Low-Velocity Projectile Weapons have half normal ½D and Max ranges, and do half normal damage. However it is important to note that bowstrings don’t work underwater making Bows and Crossbows completely ineffective. High-tech or fantasy bows, or crossbows using flexed metal would work, but should have double their normal cost.
	Guns requiring black-powder simply do not work, other guns and gyrocs have 1/20th normal ½D and Max ranges, but become Very Unreliable (malfunctions on a 14+). Modifications to normal weapons can raise this to Unreliable (malfunctions on a 16+) at +50% cost of the weapon. Specially designed weapons that have no increased chance of malfunction cost at least double the cost of a comparable firearm.
	Beam Weapons that rely on sound (e.g., Stunners & Screamers), Cosmic or Super-Science (e.g., Gravguns & Disintegrators), or Lasers that use the Blue-Green/Rainbow/Xaser options have normal range. Other Lasers have 1/10th normal ½D and Max ranges, while other beam weapons have 1/100th ranges.
	Liquid Projectors are generally useless, while Water-Cannons have 1/100th 
	Other weapons will require rulings by the GM, while weapons specifically designed to work underwater (e.g., Torpedoes) function unhindered. Round ½D ranges and Max ranges down (no minimum).

Refraction
	When attacking through the surface of water, but not at the surface, refraction of light makes it difficult to hit your target. Apply a -2 to hit penalty to any melee attack, or a -4 to hit penalty for any ranged attack that must pass from under the water to above the water or vice versa. If unfamiliar with adjusting for refraction (Gm‘s Decision), double the penalties and any roll over a 9 automatically misses.

(End of GURPS AQUATICS),
-Trachmyr

[davidtmoore]

Originally Posted by topper

*Dodge underwater is actually described in the rules. P.B.354: "Move equal to basic move/5 (round down)." But can be improved [/I]Move in other environments[/I] (P.B. 18): "You can improve water move directly for 5 pts per yard/second". This means that the avg. character underwater will have a dodge of 4 or 7 with the "step" back manouvre (that sucks yeh).
A good swimmer however would have 6/9 and one wearing flippers or webbed feet would probably get another +2 or so to move.
And with the bonuses to dodge from underwater attack, dodges seem pretty okay underwater actually.

Challenging one. I kind of agree, and did start out with those mechanics, but there was a bit of a debate on the thread about it.

Bruno's distinction between BS and BM is relevant. BM reflects your physical movement through space (displacement, in physics terms), while Dodge partly reflects that and partly maneuvering-on-the-spot ie. twisting, bending etc. Sheer movement is massively affected by drag, while maneuevering less so; if you can actually bring yourself to watch synchronised swimming, you'll see those girls can really fling themselves around.

Also, there's the need to reflect high levels of ability. Dodge/5 can really eat up the difference between characters with widely variant BS, which kind of makes for a bummer for Sam the Underwater Superninja with Speed 9 when fighting Bob the Underwater Office Joe with Speed 5. This is a slightly cinematic concern, but then characters with this kind of variation are slightly cinematic.

Originally Posted by topper

*Why would aquatic creatures [I]not[I] be affected by the water when attacking?

They're specifically unaffected by the -1 to attacks and parries, the -3 to defend, and the Swimming skill limit, as these basically relate to your comfort operating in water. Aquatic creatures don't have Swimming skill and move at full speed, so I figured the limits don't apply. They're still affected by the limits in the second and third paragraphs, as these are physical limitations.

Originally Posted by topper

*½ blowback should only be against weapons - actually the water confers momentum way better than air.

Knockback is the way you are physically knocked away by a hard blow? Hydrodynamic drag slows the movement, so you don't go as far. Not sure I understand you completely.

Originally Posted by topper

*The Bad sight (Far sighted) disadvantage. Why? If anything you´d be nearsighted. Though I personally would say that would only imply at murky water.

There's some kind of lensing effect when opening your eyes unprotected in water, that makes things in the first couple of feet blurry, but doesn't affect you further away. As Erik pointed out, there have been studies showing that nearsighted people see normally in clear water. I'm not 100% convinced myself, but it's consistent with some of the evidence.

Originally Posted by topper

*Actually takedowns and pins underwater makes sense to me. Only difference is that usually a takedown takes the opponent down, here you get into a position where a pin is possible. Since none of the combatants can swim during a takedown or pin action the combatants will slowly descend into the deep... Until someone gets a pin on the opponent, then he is in such a position he can use his feet to paddle with for 2/3 normal swim speed.

Yeah, I thought about ways of making more detailed rules, but I really only wanted a couple of paragraphs for my purposes. Pin in GURPS is specifically holding a prone victim flat on the floor with main strength and weight; holding someone helpless otherwise is kind of reflected by the various Grappling/Arm Lock options.

Trachmyr, that's a load of gumph all at once. I'll copy/paste it to a doc and give it a read-through before offering my feedback, but thanks for sharing it.

[Bruno]

Originally Posted by davidtmoore

There's some kind of lensing effect when opening your eyes unprotected in water, that makes things in the first couple of feet blurry, but doesn't affect you further away. As Erik pointed out, there have been studies showing that nearsighted people see normally in clear water. I'm not 100% convinced myself, but it's consistent with some of the evidence.

Anecdotally, I'm severely near sighted in air (effectively blind without glasses beyond about twelve inches, can't read books beyond about an inch and a half from my eyeball). I'm shockingly clear-sighted in fresh lakewater - I couldn't tell you how much correction it is, as I've never taken an eye chart swimming with me, but it's pretty amazing.

Goggles ruin the effect entirely.

[topper]

.

Originally Posted by Bruno

Dodge isn't based on Move, or Basic Move - it's based on Basic Speed. It's important not to confuse the two, despite the annoyingly similar names, because of issues exactly like this one.

My fault - true.
But I would still say that it should work based on Basic Speed. Where water applies to your basic speed as above and thus your dodge is defined by that. If that is the case it makes sense to say that one can buy basic speed (water) for +/- 5 per 0.25. Just like basic speed on ground.

Originally Posted by Bruno

"*½ blowback should only be against weapons - actually the water confers momentum way better than air."
Knockback is the way you are physically knocked away by a hard blow? Hydrodynamic drag slows the movement, so you don't go as far. Not sure I understand you completely."

Okay what I ment was that fx a water jet or similar knockback jet shouldn´t be divided. That´s why I said "only weapons.

Originally Posted by Bruno

Yeah, I thought about ways of making more detailed rules, but I really only wanted a couple of paragraphs for my purposes. Pin in GURPS is specifically holding a prone victim flat on the floor with main strength and weight; holding someone helpless otherwise is kind of reflected by the various Grappling/Arm Lock options.

So yes, weight in water wouldn´t apply - but one could still easily get into a position where the opponent is pinned - and unable to do anything. Just as if he was on land.

Originally Posted by Bruno

There's some kind of lensing effect when opening your eyes unprotected in water, that makes things in the first couple of feet blurry, but doesn't affect you further away. As Erik pointed out, there have been studies showing that nearsighted people see normally in clear water. I'm not 100% convinced myself, but it's consistent with some of the evidence.
Anecdotally, I'm severely near sighted in air (effectively blind without glasses beyond about twelve inches, can't read books beyond about an inch and a half from my eyeball). I'm shockingly clear-sighted in fresh lakewater - I couldn't tell you how much correction it is, as I've never taken an eye chart swimming with me, but it's pretty amazing.

Goggles ruin the effect entirely.

Well I´m nearsighted as well but usually uses contact lenses. I have done quite alot of swimming/diving usually without any goggles. And I see fine. I don´t believe the effect would be enough to have any real influence (game technical that is). Since a slight sight disadvantage isn´t enough to become a "game technical" disadvantage.

[davidtmoore]

Originally Posted by topper

My fault - true.
But I would still say that it should work based on Basic Speed. Where water applies to your basic speed as above and thus your dodge is defined by that. If that is the case it makes sense to say that one can buy basic speed (water) for +/- 5 per 0.25. Just like basic speed on ground.

Possible, but you end up creating a divide between heavily water-invested characters who have bought lots of Water BS and Water Move, and surface characters who haven't. You won't get many of the former except in a predominantly underwater game. Also it gets to too many new advantages and values, and I wanted a fairly simple set of rules.

Originally Posted by topper

Okay what I ment was that fx a water jet or similar knockback jet shouldn´t be divided. That´s why I said "only weapons.

Maybe water-based knockback attacks could be exempted. They're fairly rare, but it's a valid exception.

Originally Posted by topper

So yes, weight in water wouldn´t apply - but one could still easily get into a position where the opponent is pinned - and unable to do anything. Just as if he was on land.

Absolutely, but in GURPS terms that's not a Pin. It's modelled on grapples and locks.

Originally Posted by topper

Well I´m nearsighted as well but usually uses contact lenses. I have done quite alot of swimming/diving usually without any goggles. And I see fine. I don´t believe the effect would be enough to have any real influence (game technical that is). Since a slight sight disadvantage isn´t enough to become a "game technical" disadvantage.

Which is why I haven't included Erik Nielsen's suggested "compensated by near-sighted" rule; some people enjoy a significant effect underwater, some don't. But it seems enough to justify using farsighted as a way to model the usual blurring effect of being underwater.

[topper]

Originally Posted by davidtmoore

Possible, but you end up creating a divide between heavily water-invested characters who have bought lots of Water BS and Water Move, and surface characters who haven't. You won't get many of the former except in a predominantly underwater game. Also it gets to too many new advantages and values, and I wanted a fairly simple set of rules.

Hmm I would say that this is a easy set of rules, but your call really :)
You might be right about the dividing of water-invested characters and non water invested characters. But I find that both realistic and interesting. Since the average PC wouldn´t use it anyway it wouldn´t affect them.
In reality it´s effect is that a player with a Basic Speed of 6.00 who has dodge 9 on land would have dodge 4 in the water - then step back makes this 7 and aquabatics could raise it to 9 while combat reflexes (should he have that) makes it 10 - a good dodge, if it wasn´t because he was unprotected (most likely).

Which is why I haven't included Erik Nielsen's suggested "compensated by near-sighted" rule; some people enjoy a significant effect underwater, some don't. But it seems enough to justify using farsighted as a way to model the usual blurring effect of being underwater.

Absolutely, but in GURPS terms that's not a Pin. It's modelled on grapples and locks.

Hmm yeh actually your right.

[davidtmoore]

Originally Posted by topper

You might be right about the dividing of water-invested characters and non water invested characters. But I find that both realistic and interesting. Since the average PC wouldn´t use it anyway it wouldn´t affect them.

In reality it´s effect is that a player with a Basic Speed of 6.00 who has dodge 9 on land would have dodge 4 in the water - then step back makes this 7 and aquabatics could raise it to 9 while combat reflexes (should he have that) makes it 10 - a good dodge, if it wasn´t because he was unprotected (most likely).

True, but consider a dude with BS 5.00, aquabatics skill and combat reflexes, using an aquabatic retreating dodge underwater, with a final water dodge of 10. Now consider his mate with BS 9.00 and all the same skills and advantages, also with a final water dodge of 10. Thats 4.0 points - 80 CP's worth - of Basic Speed doing basically sod-all.

Or worse, imagine their other mate with BS 14.00 - at 180 CP more than the slowest guy - who has a whole magnificent one more point of Dodge than his friends.

I actually agree with you to some extent, and modelled my initial proposals on Water Move, but Erik convinced me that it's a lot easier - and fairer on high-powered, cinematic characters - to just assess a flat penalty.

[topper]

Well okay. I never have played a cinematic game and think of the rules as realistic as possible. I just believe that someone with a massive basic speed wouldn´t neccessary move or dodge fast underwater.