Ablative DR

Ablative DR (aka ADRhttp://forums.sjgames.com/showthread.php?t=160232) is shorthand for Damage Resistance with the Ablative limitation.
http://forums.sjgames.com/showthread.php?t=45476 discusses confusion on how it works with Armor Divisors.
==3rd edition==
http://www.sjgames.com/gurps/faq/FAQ3-9.html#ss9.3 covers how it used to be different:
Here's a capsule review of the problem: Attacks that don't penetrate ablative DR cannot reduce it; therefore, by taking an extremely high ablative DR, one can almost completely eliminate the likelihood of ablation occurring - making it as good as regular DR. However, the "Ablative" limitation makes DR very cheap, so it is very easy to obtain a huge DR in the first place. Moreover, even when ablative DR is penetrated, it absorbs damage for the character, effectively doing double duty as Extra Hit Points. This makes ablative DR quite a bargain!
The solution is to scrap the existing rules and use the ablative DR rules from the latest revision of GURPS Robots instead. Under those rules, every 10 points of damage inflicted by an attack removes one point of DR, regardless of whether or not it penetrated DR. This DR has a -15% limitation - just as in Robots - and "heals" at the same rate as lost HT. Characters who want their DR to regenerate more quickly may take Regeneration.
==interaction with Armor Divisors==
:2018 https://www.reddit.com/r/gurps/comments/6nhtgi/how_do_armor_divisors_work_with_ablative_dr/ refers to 2011 http://forums.sjgames.com/showpost.php?p=1223196&postcount=38 edited in 2017 to refer to 2013 post http://forums.sjgames.com/showthread.php?p=1652915#post1652915 from Kromm:
You have DR 96, HP 80. Repeated huge piercing attacks (pi++) lower DR as if ablative (footnote, p. B559), to a minimum DR 3. Against a homogenous target like concrete, huge piercing has a wounding modifier of ×1/2 once it penetrates DR (p. B380).
With 2d+2 pi++, you'll average 9 points of damage per second. You'll need 10 seconds to ablate DR 90, leaving DR 6. On the 11th second, you'll put 3 points past DR 6, which will inflict 1 HP, and also ablate down to DR 3. Then you'll be putting 6 points per second past the minimum DR 3, inflicting 3 HP per second, for the next 26-27 seconds. Total time: 37-38 seconds.
With 2d+2(2) pi++, you'll average 9 points of damage per second. But now DR is halved! You'll need five seconds to ablate DR 45, leaving DR 3. Then you'll be putting 8 points per second past half the minimum DR 3, inflicting 4 HP per second, for the next 20 seconds. Total time: 25 seconds.
The main advantage is that if you're boring dozens of these a day on a worksite – say, to pass cable – you're taking 2/3 as long to do it. That's a huge savings in labor. When you're trying to be sneaky . . . well, a rotary hammer isn't the tool for the job! But 2/3 as long to be noticed should be good for reducing whatever bonus the GM gives your opponents for a sustained racket.
:http://forums.sjgames.com/showpost.php?p=1652931&postcount=7 continues
An attack with a divisor faces less DR in the first place. It's this DR that's reduced, not full DR. If I have a divisor (2), then I need to carve away DR 40 to get through a DR 80 ablative target. On the other hand, if another attack comes along, I've only carved away DR 40, so that attack still faces DR 40, because the DR just has a little hole in it.
The footnote on p. B559 is quite explicit on this point: "Repeated impaling, piercing, and large piercing . . . semi-ablative; repeated burning, corrosion, crushing, cutting, or huge piercing . . . ablative." And p. B47 is quite clear on how ablative DR works; namely, it's carved away on 1:1 basis by damage points. This is why just about all tools intended for slicing through bulk matter are either burning (burn) or huge piercing (pi++).
==See also==
*Semi-Ablative
==References==
Category:Rules