Crevasse rescue foot prussik prerigged with munter-mule-overhand

Hi, Im new to glacier travel and mountaineering. I was wondering if this is a good idea. Normally for my crevasse rescue practice, I will simply set an anchor and then clip my foot prussik loops into the rope. I have noticed in glacier mountaineering books that a lot of people only use one foot loop, and the other side is tied to their harness. I assume this is as a backup for the waist prussik. This got me thinking, as the problem with clipping your footloops is that you then arent using an open system, and replacing the anchor point is very difficult. My solution is to prerig the harness attachment loop with a MMO, so that can be clipped into the anchor immediately but still be an open system. Here is a picture of what I am talking about:

my concerns would be that the MMO wouldn't take a fall well, and that clipping the overhands loop through the carabiner is somehow dangerous for the knot. Please let me know if you think this is an idiotic system, but I really can't see it being worse than just clipping your leg loops, other than a little harness bulk

I've read this several times and don't understand.

What do you mean by an open system? What is a closed system? Does it have to do with extending the Prussik of you haul the climber into an unprepared edge?

This seems over complicated.

I'm confused also.
Foot Prusik should be pre-rigged and kept in a pocket.
-Only should get used during self-rescue to ascend the rope.

Chest prusik should be attached to the rope (further from your body that the foot prusik, if you're on an end, or on the other side of the butterfly/figure8 if in the middle) and attached to your belay loop with a locking biner.
-Can be used to self rescue in conjunction with the foot prusik to ascend the rope.
-can be used to belay yourself or a partner in and out from an anchor.
-Can be used during Z/C pulley rescue to move along the rope, allowing rescue of another climber.

I hate those dam foot aiders attached to the Prussiks, they never cary easy and neat:(

I just rock a simple tandem Prussik belay and have a separate piece of cord tied like a dog bone runner that can store coiled up on a biner or I can use it as a foot sturup or the most common use is for using it as a probe leash.

My other favorite is a radium release draw to get you out of those welded pruusiks being loaded by weight.

Clay, I've seen and discussed with others the sort of thing you're talking about. The problem with a pre-rigged progress capture prusik is that there's a good chance there will be too much space between the pulley and the prusik, or not enough space for it to reach from the anchor to just below the pulley.

If the progress capture prusik is too far below the pulley, you'll loose a lot of progress when you stop to reset the tractors--in other words, you'll have to do a lot more hauling to make the same gain. If you have 5 inches of "slop" between the pulley and prusik, that's 15 inches of hauling distance you wasted for each tractor reset in a 3:1, and 45 inches in a 9:1. It adds up.

In the opposite case (progress capture prusik too short), you're system will just not work, the prusik will get jammed in the side of the pulley, or be otherwise somehow messed up because the prusik will put a weird pull on the load line.

I prefer to tie the prusik munter mule overhand (PMMO) at the time I'm building the hauling system, to get the lengths dialed just right.

As for keeping the foot loop from dangling down and tripping you, you could just tie up the middle slack section in a loose overhand knot.

For those who don't understand "open system", it means that the progress capture mechanism, etc, can be released while under load. Imagine a prusik loop attached to the load strand and simply clipped to a locking carabiner on the anchor. If the progress capture prusik was engaged and you wanted to back it off, you'd have a hard time because you can't loosen it. If the prusik loop is tied to the locker on the anchor with a munter mule, you can pop the munter mule and release (in control) the load. "Open system" may not be a good way to describe it, but it's a term that is used sometimes.

If you were able to haul just a few inches, couldn't you just pull the tractor side, loosen the progress capture prussik, and slowly lower the climber by letting slack out?

For sure Dave!