Damaging objects and structures

[Shimmin Beg]

I've recently started venturing into GURPS and am trying to get my head around things, so apologies if I've missed something obvious.

I'm fond of dwarves, so I've been looking at things like tunnelling (thanks, Underground Adventures!) and damaging objects. I've got stuck trying to understand some of these rules.

The point where I really got stuck is the rope arrow (Toys and Tech IV). To embed this in a surface, you need to overcome DR and inflict damage. It has an armor divisor of 3 against stone, and you can target chinks for another 2. You use the DR for 2" of materials.

(rephrased as I'm not sure how much quoting is allowed and erring on the side of caution)

From B558, the DR for 2" of stone should be 312. As I understand it, the armor divisors would stack by multiplying to 6. That leaves us needing to deal 53 damage to overcome the stone wall's DR.

A bow deals thrust+2 impaling, so to deal 53 damage it looks like we'd need to be rolling 9d before that was possible. That seems unlikely.

I can see that the rules for repeated damage would let you eventually chip through stone with your trusty ancestral pick, but that doesn't make sense for something like the arrow. Similarly, your pick can get stuck in an enemy, but I can't see how you would do something like deliberately embed it in a wall.

I'm obviously missing something. Could someone help out?

[Plane]

Originally Posted by Shimmin Beg

The point where I really got stuck is the rope arrow (Toys and Tech IV). To embed this in a surface, you need to overcome DR and inflict damage

..

your pick can get stuck in an enemy, but I can't see how you would do something like deliberately embed it in a wall.

I took a look and would take issue with the vague phrase "If it penetrates and inflcts at least one point of damage" because it doesn't seem to capitalize on GURPS nomenclature.

Even stuff that doesn't penetrate DR can "inflict damage" (Basic Damage) while the difference after subtracting DR from Basic Damage is "Penetrating Damage".

Penetrating Damage is then acted upon by wounding multipliers/divisors to determine if there is "Injury".

In the case of Fatigue Attack the injury is to the FP, but other kinds of attacks cause injury to HP or possibly to Vitality Reserve (one of the pyramids adapted that from editor notes somewhere I think)

I think in terms of Ablative DR (or Corrosive Attack vs normal DR) we should acknowledge a 3rd type though: "injury to DR".

B47 talks about ablative DR being "destroyed" and how it "heals", as does P70.

It doesn't seem unreasonable to treat the depletion of DR via your attack as "inflicting damage" since to me that seems to roughly express the idea that the result of your damage is the depletion of some kind of quantity. You "damage" FP with Fatigue Attack or "damage" DR with Corrosive Attack, even if neither are technically an "injury" to the DR's owner.

Another interesting bit is the idea of objects which provide a DR less than which they possess. Low-Tech has that: armor is protected by 1 less DR than what it provides to a wearer. No idea how to stat that as a character ("Affects Others Only: Not Self" on 1st point?) but it gives an edge case where you can damage armor HP without damaging wearer HP (inflicting EXACTLY the DR it provides to a wearer: causes 1 HP of damage to the armor but none to wearer) so if you wanted to rope-dart somebody, you might catch on their arrow even if you didn't catch on their flesh underneath it.

Of course one other weird part is how armor's HP doesn't help w/ cover DR, but that's prob ignored since it's Homogenous which only gives 1/4 the cover and most pieces of armor have less than 4 HP so it rounds down to zero? Except homogenous objects tend to get huge HP to compensate for this...

It's too bad we can't make armor Unliving AND homogenous (I don't think you can stack them) since then it'd be 1/8 HP as cover DR.

Breaking armor int osmaller and smaller pieces would hopefully lower HP to the point where you could ignore it's regular role in cover. Like for example yeah the entire guantlet might weigh 2 pounds but you're really only penetrating one side of it which would be 1lb, so you could consider the HP of the separate halves of a gauntlet when calculating cover DR from HP small enough to round down to 0 so that only the DR itself matters.

Or maybe "cover DR from HP of 1" is why the objects provide 1 DR more than what they are protected from... stuff that provides DR 1 is actually DR 0 and has HP of 4-7 in that specific section?

[Rupert]

Originally Posted by Shimmin Beg

The point where I really got stuck is the rope arrow (Toys and Tech IV). To embed this in a surface, you need to overcome DR and inflict damage. It has an armor divisor of 3 against stone, and you can target chinks for another 2. You use the DR for 2" of materials.

(rephrased as I'm not sure how much quoting is allowed and erring on the side of caution)

From B558, the DR for 2" of stone should be 312. As I understand it, the armor divisors would stack by multiplying to 6. That leaves us needing to deal 53 damage to overcome the stone wall's DR.

A bow deals thrust+2 impaling, so to deal 53 damage it looks like we'd need to be rolling 9d before that was possible. That seems unlikely.

That's the DR for two feet of stone. The DR for a 1-foot stone wall is DR156, and it seem to be linear, so for two inches it would be 156/12 x 2 = DR26. Halve that for chinks for DR13, and with divide by three (rounding down) for the (3) penetration modifier and it gives DR4 vs the arrow, and five or points of damage means you've got your rope arrow stuck into the wall.

[Shimmin Beg]

Originally Posted by Rupert

That's the DR for two feet of stone.

Thank you. I knew there had to be something simple I'd missed. Much appreciated.

On a related note, from B380, it looks like the damage from a pick would be halved for attacking a solid homogenous object like a wall or rock. It seems blunt hammers are better at breaking brick and stone than picks and chisels. Is that correct, mechanically, or have I missed something else?

[Rupert]

Originally Posted by Shimmin Beg

Thank you. I knew there had to be something simple I'd missed. Much appreciated.

On a related note, from B380, it looks like the damage from a pick would be halved for attacking a solid homogenous object like a wall or rock. It seems blunt hammers are better at breaking brick and stone than picks and chisels. Is that correct, mechanically, or have I missed something else?

It is, in terms of raw damage. I would give a miner's pick (2) penetration when used on stone, as many tools used for cutting and drilling are given that in High-Tech and Low-Tech.

[Anaraxes]

Originally Posted by Shimmin Beg

From B558, the DR for 2" of stone should be 312.

The double tick (", quotation mark, whatever else you want to call it) is an abbreviation for inches. The single tick (', apostrophe, single quote) is an abbreviation for feet.

(Obligatory Spinal Tap Stonehenge link.)