Pot Shot & Sand Trap Techniques

[PG Rob]

They work best in a certain geometry (If ground is level... between 100 and 170 degrees), so in some cases it could take a board to facilitate it.

[ratagonia]

Hmmmmm.

At that first big drop, where they talk about using a board, we usually bring a 200' rope to tie off and leave there, picking it up on the way back through. I was a little surprised to see them trying to stack potshots there. (The bad lip is on a pothole further down.)

I would say that stacking potshots for anchors is pretty tricky, and has a narrow "sweet spot". That is a big reason Steve W. came up with the SandTrap, because the stacked potshots was a very marginal technique.

That TR shows the technique pretty well. Stack up pot shots. Rappel off the bottom one. Retrieve by pulling them off the top one at a time. Sounds simple, but in practice, can be difficult to execute.

Tom

[Scott Card]

Seeing the stacking (which are great) makes me appreciate the sand trap all the more. I finally got to see the sand trap in action at Freezefest and it is so much easier, it appears, than stacking potshots. I would however take both the potshots and sandtrap in a canyon of unknown conditions, ie. mud.

[sasteve49]

Thanks Penny ... I am planning on taking both a sandtrap and potshots. I regularly use both. It was partly because of that story (Goofball) that I originally started the thread: [Help] Potshots/Sandtrap with mud???

http://www.youtube.com/watch?v=RU32NUZRfRE

This is an idea I have been playing with since last year. The concept works, but the drybag needs to be larger. Also I have an idea to close the drybag but so that it opens easily on the retieval. Fill with water, roll the top closed, insert two tongues through loops(these are sewn on the drybag.) The retrieval rope is attached to these tongues, then continues around the Sandtrap in the normal manner. We used the drybag idea once in Colt 45, but the slope was too shallow....almost held when I went over the big drop. It does obviuosly work better on a vertical lip with lots of friction. I believe Tom and Jenny have been developing this "wanchor" concept as well, but I have been out of the loop in South America for the winter.

[penmartens]

Thanks for the input so far. It is indeed enlightening.

Potshots:
-More versatile, can be tossed or used as anchor on up canyon side
-Can be filled with a variety of materials, i.e rocks, sand, mud, water
-Can be stacked although intensive with greater margin of error
-Simple setup for short drops
-Inexpensive to purchase

Cons:
Can be hard to empty
Can split on impact

Traps:
-Easy to dump
-1 trap= 1-6 potshots
-Setup is more straight-forward
-Easy to inspect, evaluate

Cons:
-More expensive initially plus requires accessories, i.e. hose, links or biners
-Geometrically sensitive placement


Both:
-Can fail without warning
-Need larger group to test
-May fail to empty completely causing harder pull or getting stuck
-May stick at obstacle or constriction

Can tarps be stacked?

Would anyone like to expound on jugging on shots/traps?

What are people using to prevent rope grooves? Is the hose being used universally? Are some using nothing? Something else?

[ratagonia]

Thanks for the input so far. It is indeed enlightening.

...

Can tarps be stacked?

Would anyone like to expound on jugging on shots/traps?

What are people using to prevent rope grooves? Is the hose being used universally? Are some using nothing? Something else?

Tarps stacked? Hmmmm. Certainly possible to stack potshots on top of a SandTrap for greater weight. Pot Shots also useful when sand needs to be moved TO the SandTrap. They both have their uses, SYNERGY!

I think the stacked Pot Shots are kinda obscure. Only the real tech-weenies will want to explore that avenue. The sweet spot on stacked Pot Shots is pretty small, and you really otta bring along a board in case the lip is obnoxious (but it can be filled with sand, if needed). The SandTrap has a much bigger sweet spot, and people grasp the parameters for safe usage much more easily.

Tom

[canyondevil]

They work best in a certain geometry (If ground is level... between 100 and 170 degrees), so in some cases it could take a board to facilitate it.

What are geometry limitations of the Sandtrap?

[ratagonia]

What are geometry limitations of the SandTrap?

The SandTrap works best if it is set into a depression, perhaps a shallow pothole, so that when you pull on the rappel rope, the Trap and its Sand has to move upward. Also, friction of the rope against the rock as it goes up and over a round edge decreases the force on the Trap.

If the pothole is too steep and deep, it can be hard to retrieve the SandTrap. Using the hose on the retrieval side can make the pull a lot easier, especially in a steep/deep pothole.

As the pothole gets flatter, the trap needs more sand. It can be used on a flat surface, but it takes quite a large pile of sand to get that to be strong. The normal form of the SandTrap is as a Taco; on a flat surface it is used more like a Tostada. Unfortunately, grains of sand act as a lubricant so the coefficient of friction is lower than it might be if the environment was clean.

Tom

[ratagonia]

What are geometry limitations of the Sandtrap?

On the other hand...

There are some geometric problems to avoid.

1. Tight narrows: if the SandTrap is bounded on both sides by canyon walls, then sometimes the sand does not spill out the sides, and the Trap cannot be retrieved. If this is the geometry available, usually the Trap can be moved further back, where the Trap can have 5-10 feet to dump out the sand before it gets into the narrows.

2. Stuff in the way: when cleaned, there is a lot of crap sliding down the drop. Ropes, fabric, straps and some sand. If there are places for the Trap to get stuck, it will. That picture of Anna rapping shows a chockstone in the way, that the Trap got stuck on. So it mainly is used in CLEAN sandstone canyons where there is plenty of sand and not many obstacles.

Tom

[ghawk]

I think the last two posts were quite useful. thanks Tom

[canyondevil]

I think the last two posts were quite useful. thanks Tom

Agreed. Thanks Tom.

[PG Rob]

I just posted a Trip Report with how we used them today.

No Kidding w/Sandtrap and Potshots

[penmartens]

Thanks for sharing your reasons for why shots and not traps. I have a few questions.
Would you give some details about stacking the shots? Why 6? Is that a magic number in some way? Do you have any tips on their usage? I see you didn't use a board.

Then, for comparison sake, has someone used a trap on the drops that PG Rob used the shots? With what results?

[PG Rob]

In general, it is best to set up as close to the drop as possible to ensure a clean pull and minimal to no rope grooves. A sandtrap has been used at every drop in the canyon. There are places where it works best, and places where I think potshots work best. You will notice earlier in the thread that the sandtrap was stuck on 2 of the drops. This was because it was set up in a compromised position (my belief).

I use 6 potshots for flexibility... You can load them up, or only fill them a little. With more, you are more versatile. If you only had a couple, you would regularly have to fill them to the brim, you likely would not be able to set up in the prime location, you are risking a clean pull and may cause rope grooving.

When stacking them, only the bottom potshot is connected to the rappel rope. It is important to remember the forces that are in play on the bottom potshot when weighted. It essentially is a wedge behind the other 5 which are for weight and friction. The bottom shot wants to pull in the direction of the rappel. The tools that are available to you are angle, friction and weight. It is essentially a multiplication formula. The greater the one, the lesser the others can be. When there is a low angle, try to maximize friction with the other shots and the rope, and fill the potshots more. When you have a better (more inclined) angle, you do not need as much sand in the potshots. You need to ensure that the friction and weight are in line (same direction) with the force that is on the bottom shot.

Since we took both a sandtrap and potshots, I thought it was not necessary to have a board.

[Scott Card]

.

Then, for comparison sake, has someone used a trap on the drops that PG Rob used the shots? With what results?

Are we talking No Kidding? If so, we did the entire canyon during FreezeFest with a Sand Trap. Worked like a charm at every drop. No pot shots used.

[penmartens]

Scott,
What did your group do, if anything, to avoid the problems that have been cited for No Kidding?
I am assuming that Spidey did the little down climb that PG Rob talked about. Anything else?

[PG Rob]

Penny,

You definitely can use a sandtrap at every drop. It is an amazing tool. It has it's place, along with all other tools. There are spots where it is the best tool and spots where it is better to use potshots.

Following is an example of a drop where it is better to use potshots. We already talked about how it is ideal to get as close to the drop as possible to have an easier pull and avoid rope grooves. You can see that the potshots can be set up almost right on top of the ridge. Notice the rope grooves next to the potshots. It is not practical to set up a sandtrap on the ridge. You would typically set up a sandtrap lower in the pothole and have to pull it up and over, which is likely what caused the rope grooves. Now, Tom's idea of using the garden hose can decrease the rope grooves and make for an easier pull of the sandtrap, but you still have an easier pull and no rope grooves with the potshots on the ridge.

[penmartens]

It looks like we have pretty well covered this subject.
I am still wondering how often protection on the pull is being used for the trap. Are people using the hose? Are they using something else? Some have suggested using 1 inch webbing as a sleeve for the pull. I am wondering about a kevlar sleeve.
I see that Oldno is back. Do you have anything to add since your trip last week?

[ratagonia]

It looks like we have pretty well covered this subject.
I am still wondering how often protection on the pull is being used for the trap. Are people using the hose? Are they using something else? Some have suggested using 1 inch webbing as a sleeve for the pull. I am wondering about a kevlar sleeve.
I see that Oldno is back. Do you have anything to add since your trip last week?

Most of the canyons where SandTraps are used are in very soft rock - therefore, using groove prevention devices should be part of the process.

We have tried using hoses, and it works part of the time, but is a pain. 3' of hose seems a good length. Splitting the hose so it could be put on the rope (rather than the rope passed through it) proved ineffective. I'll be working on a new solution to this, for release soon, I hope.

Tom

[canyondevil]

I see that PG only connected the rappel line to the bottom potshot and just piled the others on top. Wouldnt it be better to run the rap line through a rapide on each of the potshots (blocked on the bottom potshot) and pull the blocked side of the rap line through all rapides before pulling the potshots?