figure 9, 10... and beyond... for knot blocks

Ill occasionally single strand rappel w/ a gri gri by blocking the rings with a fig 8 and clipping back to the descending line. Ive been using a skinny new 8.7 lead line lately and was wondering if there were any known issues from beefing up the knot a bit by using a figure 9, or figure (some higher number); i was messing around at home last night and  things start getting pretty weird around 11...Common wisdom indicates the potential for rolling is higher on the figure 8 vs the standard overnhand... Do knot rolling concerns amplify in some kind of linear manner the higher up the "figure scale" you go?

Not too sure about the rolling tendencies but I’m a big fan of using a Binet block for these applications. Just a clove around the spine of a locker. If you like you can also use the tail of the clove to figure eight or overhand another caribiner to clip it back to the line you’re rapping on. I’ve never had it come out but even if somehow it did clipping it back to itself would prevent it from failing completely

Thanks Max, that probably is a better option when there’s any concerns about the knot width to ring hole ratio. I’ve set it up that way before and it just spooked me out a bit looking at it, but that’s just a lack of familiarity issue on my end. 

If the rings or chain are large diameter, I'll use a figure 8 bunny ears to beef it up a bit. But with clipping the other strand, it's probably not necessary.

I did get a rope stuck when knot-block rapping Tatooine in Zion. I had clipped the other strand and the biner snagged on a flake, so I try to be selective with the practice now.

Overhand vs figure eight rolling concern should not be an issue here when you are doing a knot block. You are loading the eye of the knot via the carabiner in it clipped back to the strand you are rapping on. What would roll?

Desert Rock Sports wrote:

Overhand vs figure eight rolling concern should not be an issue here when you are doing a knot block. You are loading the eye of the knot via the carabiner in it clipped back to the strand you are rapping on. What would roll?

sorry there may be some error in communication between here and the OP. I'm assuming you mean that the eye of the knot would be loaded in the failure mode of the knot pulling through the rings?

the overhand>fig 8>fig 9 and beyond rolling concerns was more of an afterthought. Since you are only ideally loading one strand of the knot block, its basically a non issue, but in hypothetical land would a figure 9 roll easier than a figure 8 in a scenario where both stands were loaded with opposing forces, as in someone mistakenly joining ropes for a rappel in that manner.

(...not a real busy day at work)

Don't overthink it. I use a schmetterling. Just make sure the biner can't possibly fit through the ring (or link) and carry on.