Aren't grates supposed to stop creature movement?

[TMNZB •☼Ž Å☼•]

The wiki makes it sound like wall grates are basically water-permeable walls, but somehow my dwarves are slipping through them. If grates are meant to be solid, which would make sense, then they don't seem to be implemented properly at the moment. I have water running towards a wall grate which empties into a cavern beneath my fort, but despite the grate blocking movement in theory, a dwarf slipped past and now I'm about to mount a rescue mission... The grate in question is sandstone, if that makes any difference.
http://dwarffortresswiki.org/index.php/Grate

[76561188078797539]

Originally posted by TMNZB •☼Ž Å☼•:

The wiki makes it sound like wall grates are basically water-permeable walls, but somehow my dwarves are slipping through them.

The answer is right there on the page you linked:

Bugs
Creatures and dwarves pushed by water flow can be pushed through wall grates. Bug:5458

By the way, I don't think this is happening when you use vertical bars[dwarffortresswiki.org] (at least never seen/heard of it), and those can also be linked to a lever (or any other mechanism) to open up as needed.

[TMNZB •☼Ž Å☼•]

Thanks!

[76561188078797539]

Originally posted by TMNZB •☼Ž Å☼•:

Thanks!

Bars linked to the same lever that will also open large enough water/magma cistern above make for excellent emergency flush system :)

[harlequin_corps]

Also dodging and being flung by debris.. any sort of autonomous movement. They skite right through fortifications the same way. The grate just stops pathing, Deliberate movement.

[76561188078797539]

Originally posted by harlequin_corps:

Also dodging and being flung by debris.. any sort of autonomous movement. They skite right through fortifications the same way. The grate just stops pathing, Deliberate movement.

Have you seen this happen with bars?

I generally tend to play in a boring way and avoid similar situations in the first place, so not many opportunities to check, and the !SCIENCE! involved to verity would require more time than I can commit.

[Helios]

Pressure is one of the reasons they can pass i think if you dig at the corners water can stil pass but it is slowed down.

[inthecorner]

Originally posted by Sheepify:

Originally posted by TMNZB •☼Ž Å☼•:

The wiki makes it sound like wall grates are basically water-permeable walls, but somehow my dwarves are slipping through them.

The answer is right there on the page you linked:

Bugs
Creatures and dwarves pushed by water flow can be pushed through wall grates. Bug:5458

By the way, I don't think this is happening when you use vertical bars[dwarffortresswiki.org] (at least never seen/heard of it), and those can also be linked to a lever (or any other mechanism) to open up as needed.

Definitely also happens with bars, my bathtub has a very high kill count as a result.

[dimm_ddr]

Originally posted by Sheepify:

Originally posted by harlequin_corps:

Also dodging and being flung by debris.. any sort of autonomous movement. They skite right through fortifications the same way. The grate just stops pathing, Deliberate movement.

Have you seen this happen with bars?

I generally tend to play in a boring way and avoid similar situations in the first place, so not many opportunities to check, and the !SCIENCE! involved to verity would require more time than I can commit.

I did not tried bars, but it definitely can happens with fortifications. Both carved and built.

[TMNZB •☼Ž Å☼•]

In conclusion, any moving water is hazardous to dwarves?

[dimm_ddr]

Originally posted by TMNZB •☼Ž Å☼•:

In conclusion, any moving water is hazardous to dwarves?

No, moving water itself is just a small inconvenience. Place where it can move a dwarf - that is where the danger is.

[captainamaziiing]

I have a standard j-bend water input feeding an internal reservoir, topped by a standard stone grate and the whole pitch to the j-bend was that baddies can't damage the grate one z level up so they can't get in.

All the fish in my reservoir have convinced me the j-bend is waste of time. It's easier to get in that way than the front door, because you have to walk through the door. The j-bend you just hold your breath and the water brings you in like flotsam in the tide.

[TMNZB •☼Ž Å☼•]

A couple more questions -
Can falling water (or the dwarf falling vertically) force dwarves through floor grates in a similar way to how flowing water can force them through wall grates?

Is the only guaranteed way to prevent dwarves migrating past a wall grate, to ensure that there is no flow of water in the direction of the grate?

[dimm_ddr]

Originally posted by TMNZB •☼Ž Å☼•:

A couple more questions -
Can falling water (or the dwarf falling vertically) force dwarves through floor grates in a similar way to how flowing water can force them through wall grates?

Is the only guaranteed way to prevent dwarves migrating past a wall grate, to ensure that there is no flow of water in the direction of the grate?

No, to my knowledge floor grates are perfectly safe.
Water flow is not the same as water movement in DF. There can be flow without movement, in the river for example. Such flow would not move anyone or anything. Case is that most important in practice is that if you have 7/7 water, it does not mater if there is a flow or not - it would not move anything. Movement only happens when there is a difference in the water depth in adjacent tiles. But yes, only guaranteed way to prevent dwarves from being pushed through is to not have a dwarf on a tile when water moving inside fortification/wall grate/bars.