800' Rap in the watercourse, BMS microrack vs. Scarab

Discuss vertical caving, equipment, & techniques. Also visit the NSS Vertical Section.

Moderator: Tim White

800' Rap in the watercourse, BMS microrack vs. Scarab

Postby stupidjak » May 3, 2018 9:11 pm

I have a question about micro racks for long rappels in the watercourse.
My friends and I use ATS devices for everything. I just ran a canyon with a 650’ waterfall in the watercourse on a Sterling 9mm CIV rope. It was a complete pain, I had to feed the heavy rope up through the device for the first half of the rappel. I’m planning on doing some 800’ waterfalls soon and am considering getting a rack so that I don’t have to feed the rope. I’ll likely be using an 8mm rope (Bluewater, Canyon Extreme).
Considerations and questions:

I’m considering a BMS microrack, short frame, duel hyperbar vs. titanium Scarab. Cost isn’t an issue. I really don’t want to have to feed heavy rope and I hear that it’s dangerous with racks to feed cuz the bars pop off (this is terrifying to someone like me who hasn’t used one BTW). Does the Scarab have enough friction with its single bar to start out without any wraps and then allow to start adding wraps half-way down? Is the one wrap+1bar on the scarab have little enough friction to allow starting a no-feeding 800’ rappel?

We like to zip down fast and almost always have water cooling the device.

I like only having to have my right hand needed to brake with the ATS, because I might have to use my left hand for something else, especially if I’m getting blasted by a lot of water. The rack seems to need a left hand to position the bars, so maybe dangerous? Are racks OK in major watercourses (like where you are holding your breath and can’t even pop your head out)?

Can you use an autoblock on a rack? They seem like bars can pop off and reduce friction (or I might need to use my left hand and therefore accidentally lose friction) and an autoblock might be a nice backup.

In my experience, every rappel device that has ever claimed to be able to “easily add friction” during rappel (adding a horn to a Squrl, ATS etc.) is complete BS. When I add a horn the amount of friction added is way too extreme. This ends up making the rappel either too fast or too slow. Adding a second horn means stop. The Scarab adds horns and I’m worried the same phenomena may happen. I hear that the hyperbar on the microrack has the same issue, so I’m imagining using them only when locking off. The rack seems superior because there is never a need to wrap a horn.

When you near to the bottom of an 800’ rappel on a wet, stretched-out, 8mm rope, will a microrack offer enough friction without engaging a show-stopping hyperbar?

Thanks in advance guys! I tried researching this stuff but couldn’t find these answers.
stupidjak
New Poster
 
Posts: 1
Joined: May 3, 2018 9:04 pm
  

Re: 800' Rap in the watercourse, BMS microrack vs. Scarab

Postby GroundquestMSA » May 5, 2018 7:28 pm

Unless you're a great big fatso, avoid the short-frame micro. It will be too slow. Long frame BMS is much better, the hyper-bar is easy to use and doesn't add full-stop friction. The left hand does not really control bars on a micro rack. They are where they are. Right hand friction and angle control will do most of the work, though, as you've noted, the left hand should be engaged if you need to feed rope, the danger is that a bit of slack can form when feeding, allowing the bottom bar to swing open and reducing your friction from 4 bars to effectively zero. I've never used a scarab but it will probably have less friction in the most basic configuration, and will certainly twist rope more than a micro w.hyperbar as friction is added.

Yes you can use safeties of many sorts, though I never do so won't offer an opinion.

800' is a long way. Feeding may be inevitable with any standard device. A traditional rack with ss bars or more likely a long-frame may be exceptions.
User avatar
GroundquestMSA
NSS Hall Of Fame Poster
 
Posts: 1349
Joined: May 5, 2011 1:32 pm
  


Return to On Rope!

Who is online

Users browsing this forum: No registered users