Descender question

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Descender question

Postby Smeg » Dec 27, 2011 2:59 pm

I have a question on descenders.

I have a standard figure 8 that I have always used to do rappelling with. In caves and out I have never rappelled further than 150' but that may change in the future.

Right now I have been looking at getting a new figure 8. In particular the Petzl Pirana

I am comfortable and familiar with figure 8's and I like how this one allows you to easily lock off and be hands free with it. What I want to know is why would a rack be so much better than the pirana if I would not be crossing any knots or doing anything over 150'?

To me this seems easier and a lot less complicated (hence less likely to mess up) than any type of rack I have seen.
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Re: Descender question

Postby Extremeophile » Dec 27, 2011 3:18 pm

As you may already be aware, the Pirana isn't a classical figure 8 in that the rope isn't passed around the base of the eight. This allows you to insert and remove the rope without detaching the device from its carabiner or detaching the carabiner from your harness. The path the rope takes means that there is significantly less twist added to the rope, and you have 3 different ways to thread the rope depending on your need for more or less friction (not counting the horns).

I think it's perfectly suitable as a rappel device for shorter drops in caves. I've used it on drops up to 300' in canyons on ropes from 8mm to 11mm without issue. The main concern for cave use is that it is made of aluminum and probably won't last very long when exposed to gritty ropes. A stainless Pirana would be a nice bit of gear. Others will probably comment on other devices being better suited for caving due to better durability, better heat dissipation, better friction control, etc. However, they also tend to be heavier, bulkier and more expensive. Bobbins and racks are standard equipment for caving for many reasons, but a Pirana will also work.
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Re: Descender question

Postby Cody JW » Dec 27, 2011 5:16 pm

I agree with Extremeophile. I prefer the 8 ( or similar) for short drops. Many cavers seem to prefer a steel 8 over anything alum. This debate on the 8 is well worn. Many will warn you of a twist in the rope and many cavers prefer not to have any aluminum rappel devices on their ropes. The owner of the rope is well within his right to say what rides his rope. My personal opinion is the benefits of the compactness of the 8 or similar outweigh the perceived drawbacks for short drops. For long drops you need to consider the ability of the device to dissipate heat and with that in mind a full size rack has the advantage. The choice of 8 vs rack has alot to do with the depth of the drops you plan to do. For caving you might want to consider the steel 8 if you like the 8 for its size benefits.
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