A really good sword

[Jinumon]

Originally Posted by Rolando

a leaf don't have enough mass to make "slam" attack that do even 1d6-5, not at "flowing in the river" speed.

Well obviously. A single leaf only weighs about one-twentieth-of-an-ounce. Doing such calculations would required the numbers in the equations to be scaled up several orders of magnitude. Still, it's possible.

Jinumon

[Stormcrow]

There are two possibilities. Some people can have supernaturally or cinematically sharp swords in the setting, or the setting simply considers Very Fine swords to be so sharp that they can cut in this way.

The latter is just a switch you enable on the setting. If you make a Very Fine sword using mundane means, you too can do this.

The former is a new category you just have to invent, or else you have to decide what kind of magic substitutes for pure sharpness. I might consider such a weapon to have a Penetrating Weapon enchantment on it, giving it an armor divisor. The actual test of cotton in the water or whatever is just a bit of fluff that GURPS won't mechanically replicate. In settings like these, surely every knight worth his salt has a Penetrating Weapon, and the stories show the knights showing off how their sword has a bigger armor divisor than everyone else's.

[Varyon]

Originally Posted by Jinumon

Well obviously. A single leaf only weighs about one-twentieth-of-an-ounce. Doing such calculations would required the numbers in the equations to be scaled up several orders of magnitude. Still, it's possible.

Jinumon

I eyeballed this, and it really doesn't work out. Given a leaf has n HP (it really doesn't matter the number here, given the next bit), that the GURPS Slam equation is Speed*HP/100 dice, that a collision with a cutting surface does half damage, and that cutting does x1.5 Injury, to have a chance at destroying the leaf (maximum damage reduces to -1xHP; leaf still needs to fail an HT roll to "break") you need the stream flowing at a rate of around 22 yards per second. That's slower than the maximum recorded velocity of Niagara Falls (68 mph, or 33.24 yards/second), down at the bottom of the drop, but markedly faster than the rapids leading up to the falls, which are only around 12 yards/second (dealing a bit over 50% HP in Injury with maximum damage). Were it not for that "collision with a cutting surface does half damage" bit, the rapids would work, but not the relatively calm streams one thinks of relating to the legend.

[Anthony]

Honestly, that level of sharpness doesn't have much to do with quality, because the sharper the edge the faster it gets dulled on contact with hard materials.

The story about Richard and Saladin isn't actually apocryphal, it's fictional (it apparently dates to a book by Sir Walter Scott, "The Talisman"). In the same scene King Richard chops through an inch and a half steel bar (extrapolation from B558 suggests DR 33/HP 66, meaning King Richard was doing 22d with a swing, though there's inconsistency, if the rod was merely iron with DR 18/HP 35 he only needed to be doing 12d).

[Jinumon]

Originally Posted by Varyon

I eyeballed this, and it really doesn't work out. Given a leaf has n HP (it really doesn't matter the number here, given the next bit), that the GURPS Slam equation is Speed*HP/100 dice, that a collision with a cutting surface does half damage, and that cutting does x1.5 Injury, to have a chance at destroying the leaf (maximum damage reduces to -1xHP; leaf still needs to fail an HT roll to "break") you need the stream flowing at a rate of around 22 yards per second. That's slower than the maximum recorded velocity of Niagara Falls (68 mph, or 33.24 yards/second), down at the bottom of the drop, but markedly faster than the rapids leading up to the falls, which are only around 12 yards/second (dealing a bit over 50% HP in Injury with maximum damage). Were it not for that "collision with a cutting surface does half damage" bit, the rapids would work, but not the relatively calm streams one thinks of relating to the legend.

You're almost certainly right. That said, how much is a "+2 damage" when compared to the microscopic HP of a leaf? I realize I'm sort of splitting hairs (leaves?) here.

Jinumon

[zoncxs]

Originally Posted by Varyon

I eyeballed this, and it really doesn't work out. Given a leaf has n HP (it really doesn't matter the number here, given the next bit), that the GURPS Slam equation is Speed*HP/100 dice, that a collision with a cutting surface does half damage, and that cutting does x1.5 Injury, to have a chance at destroying the leaf (maximum damage reduces to -1xHP; leaf still needs to fail an HT roll to "break") you need the stream flowing at a rate of around 22 yards per second. That's slower than the maximum recorded velocity of Niagara Falls (68 mph, or 33.24 yards/second), down at the bottom of the drop, but markedly faster than the rapids leading up to the falls, which are only around 12 yards/second (dealing a bit over 50% HP in Injury with maximum damage). Were it not for that "collision with a cutting surface does half damage" bit, the rapids would work, but not the relatively calm streams one thinks of relating to the legend.

The reason this does not work is because of 2 things.

1 - ST damage table does not reflect how much damage something should do.

2 - Slams don't reflect damage correctly when compared to slams.


Using your logic, Someone a shortsword, which has HP 10 getting hit by a sword should take:

((10xV/100)/2)

assuming no bonus to weapon damage from quality and V of 1-50 yards a second:

.05 - 2.5 = 1d-3 to 3d of cutting damage <- that is how much damage the sword will do to any object it collides with. Double this if the SM is is big enough that the sword acts as an immovable object. Which in the case of sword vs leaf, it counts. so damage is really = 1d-3 to 5d of cutting damage.

The sword can't do more dice of damage to the leaf than the leaf can do to the sword, but the leaf would obviously have a HP score less than 1 but not 0, so the damage is calculated as (assuming 1 HP):

((2xV/100)/2)x2

that gives us a range of: 1d-3 to 1d

so a shortsword, using slam calculations, will have a hard time cutting a leaf floating into it at slow speeds of water, normally. But a very fine sword should be able to do it with ease since it has +2 damage.

[Tomsdad]

Given the set up I can see how it would work. The strand is floating in the continuous current and once it hits the blade assuming it's not carried past it it will be subject to the sustained pressure of the current pushing it against the blade. I.e. it could eventually part itself against the blade under such sustained pressure.

So I think this is less extreme anecdote than dropping leaves onto an upturned blade in the air etc.

(on the chopping silk to pieces in the air, it going to depend on how big the silk scarf is, the larger and thus heavier the more resistance it will offer which in turn will allow the blade to engage with it more and cut better).

[Rupert]

The amusing thing is, a really good sword shouldn't be that sharp. An edge that sharp and fine would dull very quickly, especially if you hit metal armour or a metal shield boss or rim with it (or bone, for that matter). Better to have a slightly less sharp edge on a less fine blade and have it stay sharp for longer, and not risk the blade getting folded over or plain mangled.

Also, just about any knife can be sharpened to an extreme degree. The trick is getting steel that will hold the edge. Then, having found that, finding one that isn't too brittle. High, but not extreme hardness and very good wear resistance is often the best combination. Oh, and the better it holds and edge, the more effort it takes to get the edge on there to start with.

[malloyd]

Originally Posted by Rupert

Also, just about any knife can be sharpened to an extreme degree. The trick is getting steel that will hold the edge. Then, having found that, finding one that isn't too brittle.

Yeah, these sorts of things are not really a test of the quality of blade, but of how much work has been put into sharpening it just before the test. And a lot of sharpness tests don't really even do that - the cut a dropped tomato one that some kitchen knife advertisers use for example is one that even badly dull knives will pass.

It's entirely possible to put a razor edge on a piece of junk - I've actually seen somebody put a hair shaving edge on a plastic knife just to prove he could. The quality difference is it only worked for a couple strokes.

[Rupert]

Originally Posted by malloyd

It's entirely possible to put a razor edge on a piece of junk - I've actually seen somebody put a hair shaving edge on a plastic knife just to prove he could. The quality difference is it only worked for a couple strokes.

One of my father's things was to put incredible edges on old butter knives (which, tending to have thin blades, are often quite easy to sharpen) at knife shows. They'd lose their edge pretty fast though, being cheap mild steel at best.

On the other hand he's got a knife he made of O1 tool steel that was hardened but never tempered and it's never needed re-sharpening. It's also got no spring in the blade at all, and we assume that if dropped onto a hard floor it'll snap, if not shatter.