by CaveStar » Oct 12, 2005 2:16 pm
I'm going to be very interested in this one. As anyone who followed the vertical chats on the old board knows, I'm a fan of the the double-brake concept and I use a big old SRT double-brake model which is pretty much bombproof, though on the heavy side.
I've seen the Anthron device, though I have not had much chance to practice with it. The Oregon guy who had it did indeed say that it was hard to move on dirty 11 mm rope but he liked it for clean new 11 or for 10 and 9. Well, wet dirty 11 is one of those realities that you do have from time to time. So I have not been inclined to go further with the Anthron.
I have not seen the Kong at all and have been curious about it.
This new SRT one has some slight resemblance to the Anthron in that it looks like it would have the rope exposed as it passes through the device -- any thoughts about the good/bad of that?
I've also wondered about heat dissipation. The bigger the device, the more metal, hence the better the device is at dissipating heat so it doesn't fry the rope -- as a general statement. So, presumably, my old SRT at 18 ounces can dissipate more heat and thus be used on a longer pitch than the Petzl stop at 12 ounces, in a way somewhat analogous to how a long rack will dissipate heat better than a minirack.
In the the Northwest we mostly have shorter (40-75 foot) pitches, sometimes in series. People routinely use miniracks and Petzl stops, which are fine for pitches of these lengths and can be used on pitches somewhat longer. I would tend to extrapolate out a bit from those limits to determine my own limits, since my device is heavier. But what are those limits? People disagree.
I've heard people say that they wouldn't cave on a Petzl stop more than a hundred feet at the very outside. I've heard others say that they'd go 200. I used my SRT on a 160-footer and it was pretty warm. I would have said my speed in descending was pretty moderate; nobody said, well, you were sure hotdogging it down that there rope. At the bottom I expressed some concern about it, since I don't usually do pitches long enough for heat to be an issue, and was told, yeah, the stops will get pretty warm and it's normal and it's okay as long as you keep moving.
Well, is it really normal?
I've wondered how much farther I could go with my device on a rope before I'd be in the zone where the device would get too hot.
And for that matter, how hot is too hot? Obviously there's no way to measure it objectively under caving conditions (here, stop on that rope and let me attach this thermometer to your descender -- yeah, right!). On the other hand I don't see waiting until I've already fried a rope before saying, well, now we know what is too hot.
Comments, anyone?