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Old 08-07-2020, 03:09 AM   #1
Anders
 
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Default Question about bone armor

Low-Tech Armour has rules for bone armour (not very effective, but possible). It is semi-ablative. If it was damaged, could it be repaired with suitable materials and Armoury (Body Armour)?

Also, how does it interact with armour divisor?

Example: Nick has bone armour with DR 3, giving it 30 HP. He is hit by a metal weapon that does 10 points of damage. The bone armour stops 3 of them, reducing it's hit points to 27. Now he is hit by a stone weapon that does 10 points of damage. The bone armour stops 6 points of them, because it has an Armor Divisor of 0.5. Is the bone armour's hit points reduced by 3 or 6?

Edit: Semi-ablative armor has its DR reduced by 1 per 10 points it has stopped. I'm using HP to keep track of how many points it has stopped. It may not be strictly accurate but it works.
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Last edited by Anders; 08-07-2020 at 05:52 PM.
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Old 08-07-2020, 07:13 AM   #2
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Default Re: Question about bone armor

I'd allow repair using the usual Armoury skills.

The AD-ablative interaction is covered in the uFAQ. Kromm's example has basic damage applied to the "effective" DR (my term, not Kromm's), post AD. It does use AD > 1 in the example, halving DR from AD 2 and applying basic damage to the halved value to figure out how long it takes to ablate it away.

Even that doesn't specifically address fractional DR, though. So the conclusion that you get an increased effective DR for ablation purposes with fractional AD is still an inference from what's not said to be different.

(If you apply that principle to the rules in Basic, Kromm's example is wrong, because ablation on 47 doesn't say anything about AD, and AD rules on B378 say nothing about ablation. "Doesn't say otherwise" leads to the conclusion that AD is irrelevant to ablation.)

I'd do the calculation with "effective damage" used for ablation purposes for fractional AD as well. The bone armor suffers 6 HP loss from stopping 3 points of basic damage, because it seems that the point of calling armor "ablative" is to reflect the fact that it's relatively brittle and fragile to different forms of damage., which property materials have to different degrees. And AD is the only way to reflect that.

You could halve the HP of the armor instead. That makes sense until you think about multiple attacks with different ADs hitting the same armor. One of them sees "half HP" and the other sees "full HP", so there's not a good way to combine that damage. You'll have to do the same math on one end or the other. If you take "effective DR" of damage, then at least you don't have to fiddle with the HP stat or track fractional HP on armor.
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Old 08-07-2020, 08:35 AM   #3
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Default Re: Question about bone armor

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Originally Posted by Anders View Post
Low-Tech Armour has rules for bone armour (not very effective, but possible). It is semi-ablative.
Interesting, could that be grounds to treat living bone (skull/spine DR) the same way, or only dead bone?
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Old 08-07-2020, 09:55 AM   #4
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Originally Posted by Plane View Post
Interesting, could that be grounds to treat living bone (skull/spine DR) the same way, or only dead bone?
Dead and dry bone is very brittle compared to living bone. It's basically very porous stone at that point.
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Old 08-07-2020, 11:21 AM   #5
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Default Re: Question about bone armor

The equivalent for living bone would probably just be to allow cumulative damage to cripple limbs rather than requiring a single injury above the "break" point to do so.
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Old 08-07-2020, 11:31 AM   #6
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Default Re: Question about bone armor

Quote:
Originally Posted by Anders View Post
Low-Tech Armour has rules for bone armour (not very effective, but possible). It is semi-ablative. If it was damaged, could it be repaired with suitable materials and Armoury (Body Armour)?

Also, how does it interact with armour divisor?

Example: Nick has bone armour with DR 3, giving it 30 HP. He is hit by a metal weapon that does 10 points of damage. The bone armour stops 3 of them, reducing it's hit points to 27. Now he is hit by a stone weapon that does 10 points of damage. The bone armour stops 6 points of them, because it has an Armor Divisor of 0.5. Is the bone armour's hit points reduced by 3 or 6?
Unless I've missed something, that's not the way semi-ablative works. Semi-ablative means the armor suffers a -1 to DR for every 10 points of damage it prevents (or maybe every 10 points dealt, I've never been entirely clear on that), and HP doesn't factor in. If instead using the optional Damage to Armor rules from LTC2, rigid armor (like bone armor) is homogenous and has DR equal to the DR it provides, minus 1 (for DR 3 bone armor, it has intrinsic DR 2). So, a 10-point hit with no armor divisor deals 8 damage past DR to the armor (7 past DR to the wearer), while a 10-point hit with a (0.5) armor divisor deals 6 damage past DR to the armor (4 past DR to the wearer); the Injury suffered by the armor depends on what wounding type the weapon has. There doesn't appear to be any guidelines for interactions between that rule and the rules for ablation; personally, I'd be inclined to have semi-ablative function differently when using the Damage to Armor rules, probably treating any semi-ablative flexible armor are homogenous rather than diffuse and having DR decrease proportional to HP, reaching DR 0 at HP 0.
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Old 08-07-2020, 11:44 AM   #7
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Default Re: Question about bone armor

I would think that repairing damaged bone armor would necessarily be done by replacing damaged elements of it. You can't really repair bones. Unless maybe you've got a glue that's stronger than the bones are?
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Old 08-07-2020, 11:58 AM   #8
Flyndaran
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Default Re: Question about bone armor

I can really only see scale bone armor as making any sense at all. With that, you just replace the broken bits.
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Old 08-07-2020, 12:26 PM   #9
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Default Re: Question about bone armor

Quote:
Originally Posted by Tyneras View Post
Dead and dry bone is very brittle compared to living bone. It's basically very porous stone at that point.
In terms of GURPS Low-Tech "damage to armor" rules, that might be the difference between Rigid armor using IT:Homogenous and Flexible armor using IT:Diffuse?

That's another way (other than Semi-Ablative) to represent "1 damage doesn't drop 1 DR, but lots of damage graudally lowers DR" since LT's DTA does something like halving DR at at 1/3 HP.

Living bone (with flexible-diffuse HP) would take a lot more punishment before breaking than dead bone (with rigid-homogenous HP) basically, using this proposal.

Instead of "half at third" treatment for DR/HP (reminds me of 1/2 ST at 1/3 FP under traditional Fatigue rules) a more gradual system (like Cole's -5% ST per 10% FP loss: giving -50% at 0 FP instead, and -100% at -1xFP) leading to pointy-by-point DR loss would be cooler for high-DR armor.

That isn't relevant to skulls with 2 DR though (1 point is 50%) unless using tenths of damage/DR, which is fun-crunch to some (just one column after a decimal point can be palatable) but yucky to others.

What I would like about calculating HP (based on mass) for the skull and spine (to determine when to reduce their DR, using the DTA rules in Low-Tech) is you might potentially do that for other bones too, and have other bones perhaps assign some levels of DR as well, mostly for purposes of absorbing 'hurting yourself' being applied at lower thresholds, and for having another mechanic besides wound multipliers to distinguish between LT's new sublocations of limbs (upper arm v forearm, shin v thigh)
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Old 08-07-2020, 12:53 PM   #10
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Default Re: Question about bone armor

Bone armor would look like this. It should be easy to repair. Protects as horn armor (DR 3).
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