Monday, 22 August 2011

Should encumbrance reduce armor class?

The June / July talk about dexterity, AC and shields had me wondering about the role of encumbrance.

From my understanding of D&D's early history AC was just that, the armor class, that was determined purely by the type of armor worn.

Then things like dexterity started to modify AC, until it really should have been called Defence, since it was gradually being divorced from the armor type. This is even more apparent if we wish to consider the proposal that dexterity = armor class.

The appealing motivation of such a change is NOT to become more simulationist, D&D combat is at it's best when abstract, but it is increasing incentives to player choice that is most attractive.

In one of my most popular posts ever I wrote of my frustration that starting at Level 1, characters could afford the best non-magical armor in the world, plate mail. Why then should they care for chain, ever?

I still stand by that proposal and in my recent campaign the cost of armor is drastically increased.

Armor            AC   Cost     Enc
Leather           7       5        150
Chain Mail     5    150       300
Plate Mail       3    400      450
Shield            -1      10      150

When I played Keep on the Borderlands my players even contemplated casting a sleep spell on the town guard just to get their hands on some chain mail! The first two gaming sessions, if they had a theme, would have been the "Search for better armor'
So the new costing was a great success.

But eventually characters that are allowed armor find plate mail and that's the last they contemplate any other armor source. And certainly wearing no armor by choice, is just nonsensical.

It is no wonder then that D&D combat rules struggle to model for unarmored duelists, firearms and a myriad of other additions to a campaign setting you might wish to add.

It was thinking about firearms that led me to some new considerations on this topic.
It was the ability of firearms to penetrate armor that led to the fall in armor use in the late middle ages. I say fall, because armor certainly didn't die out as a concept.

The famous Australian bush ranger Ned Kelly in the 1800's put some armor to some short but iconic use.

In the end the lumbering knight gave way to the mobile cavalry, pikemen and red coats.
Protection was replaced by mobility, because in the world that was emerging, mobility was the new protection.

Some have modelled the power of firearms against armor by giving firearms armor penetration. I think this is an ok model if it is not based on a false conclusion. If I'm being shot by a bullet I don't suffer more damage because I am wearing armor, I suffer less. The reason wearing heavy armor against firearms on the battlefields may not be such a good idea, is because I am less mobile and more likely to have the bullet (or shot) hit me in the first place.

Now this could be modelled as weapon (firearm) vs AC.
Chain Mail +1 to hit
Breast Plate and helmet alone +1
Plate Mail +2
Plate +3

But what we are really saying is not that the bullet is better at penetrating plate armor then chain mail, it clearly isn't; no we are concluding that someone in plate is less mobile then someone in chain mail, and thus easier to hit. But, any visit to a historical reenactment, or the UK Royal Armoury in Leeds, will quickly dispel the myth that armor decreased in mobility in nice step wise increases in armor strength. So it isn't really that easy to say plate mail is much worse than chain. It might be, but it depends.

In D&D however, we already have a rule system in place to deal with issues of mobility, it is called encumbrance.

Now to a question? How often in your campaign does the character's mobility effect game play? Honestly, how often do your players get chased so that their movement rate is the difference between life and death?

I would think that most players, if they think of encumbrance at all, it is not in terms of their character's movement rate but in terms of how much they can carry.

Many of us are lackadaisical when it comes to keeping tabs on movement rate and it's enforcer, encumbrance. But with Raggi's rules or my own adaption of Delta's 150cn = 1 dungeon stone rules (outlined again below), encumbrance is fairly easily accounted for.

So how could penalties to AC based on encumbrance incentivise player choice?

1. It makes chain mail +1, or elven chain, a worthy, even superior, competitor to plate mail.

2. It makes a high dexterity character consider their armor choices carefully

3. It allows heavily encumbered characters to be missile targeted more easily (opening up firearms as a deterrent to heavy armor)

If we adapt from B/X

ENC             Mv          AC penalty       
<400             120'               0                     
401-600          90'              -1                      
601-800          60'              -2                      
801-1600        30'              -3                     

B/X armor rules
Leather         AC 7       200cn
Chain mail   AC 5       400cn
Plate mail     AC 3       500cn
Shield          -1 to AC  100cn

Or from my last post an alternative chart that emphasises the roll of initiative:

Movement (Encumbrance)
as determined by feet/turn
-1 personal initiative 
-1 personal initiative and - 1 AC vs missile weapons
-2 personal initiative and - 1 AC vs missile weapons
-2 personal initiative and - 2 AC vs missile weapons and - 1 AC vs melee

Perhaps, just perhaps, player consideration regarding what type of armor to wear, just for a moment, there was umm... maybe I won't wear this plate mail.

My encumbrance rules for strength

Notes regarding movement, strength and encumbrance.

Max Enc in Stone Weight
150cn = 15 pounds = 1 stone weight

Encounter Speed / round
1/5 Strength =

2/5 Strength =

3/5 Strength =

4/5 Strength =

5/5 Strength =

>5/5 Strength =
Run speedx3; explore speed x3 /turn

Encumbrance effects on Movement
120’ up to Str*1/5 in dungeon stone (1 dungeon stone = 150 coin encumbrance)
90’ up to Str*2/5
60’ up to Str*3/5
30’ up to Str*4/5
15’ up to Str*5/5
Can carry an additional 50% if not dead weight (eg piggy back) or dragging along the ground

150 coins = 15 pounds = 1 'dungeon stone' (as opposed to the normal 14 pounds = 1 imperial stone)
Strength score is multiplied by a fraction to determine max encumbrance for that given movement.
eg Strength 3, max encumbrance 3*5/5 = 3 dungeon stone = 45 pounds = 20kg or 30 kgs dragged along the ground. I think this might be reasonable for the AVERAGE 9 year old, who using grip strength as a real life comparator has strength of 3.
eg strength 10 average, max encumbrance 10*5/5 = 10 dungeon stone = 150 pounds = 68kg (I think this is pretty acceptable, I'm average, I could barely move with 68 kg unless I was piggy back someone, and I think my 50% increase rule, allows something almost realistic but simple to apply.
eg strength 18, max encumbrance 18*5/5 = 18 dungeon stone = 270 pounds = 122 kg.
Personally I think olympic weight lifters can be said to have strength exceeding normal human range.


  1. 1st level fighters can afford plate because 1st level fighters are CHAINMAIL leaders (normal men with +1 hit points, dmg, thac0). Chainmail describes leaders as having the best weapons ad armor for their time and society.

    A 1st level fighter is a veteren who has already seen war, why wouldn't he have a suit of plate?

  2. Good point UWS guy - and certainly the 1st level fighter is called a veteran reflecting the Chainmail table top wargaming origin of D&D (veteran compared to a normal man).

    But for me - I like my 1st level players soft and crunchy - it keeps them more acquisitive that way, and gives me reason not to start having to hand out magic items so quickly and so powerfully.