Sunguramy :nb_lily:<p><a href="https://flipping.rocks/tags/Karstmas" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Karstmas</span></a> day 2!</p><p>There were questions about techniques used on my last share, so I thought I'd make the next few days a bit more educational. (Read alt text too for more info!)</p><p>Firstup, what is SRT? Single Rope Technique (SRT) is the technique used in caving, which the descent and ascent is solely on the rope. This is distinct from rock climbing; ideally we don't want to have the rope touch the rock since that is an abrasion nightmare. There are a lot of ways to deal with this which I won't get into, but the basics are: rock climbers climb rock, SRT folk climb rope.</p><p>Since caves are holes in the ground, let's start with descent. There are lots of descenders invented over the years, especially in the early days. Rappelling hammers, WhaleTail, various methods of rope wrapped through carabiners, and we must not forget the ever popular body rappel which the 'gear' was sewing in leather onto your jeans so you can wrap the rope around your body (ouch!). None of this really worked that well. </p><p>Enter: the Rappel Rack. Originally "Brake Bar Rack" (guess what it was made with!) it was invented by John Cole, a NASA engineer, in 1966. It was simple in design and build, and inexpensive. He never patented the device so anyone could easily make one. There were a few original variations, but it soon settled into the standard 6-bar 14" rappel rack generally seen today (although brake bars are no longer used, ha!). </p><p>Variations of the Rappel Rack have come around, but many ignore what made this an engineering marvel. The length allows for bars to spread and squish up along it's length, varying the friction on the rope weaved through it. Bars can be added and dropped while on rope, further increasing adjustability. 60% of the friction is held by the upper few bars, and a minimum of 4 bars needs to be used for safety limits. </p><p>Why does friction, and ability to adjust it on the fly, matter so much? If you are doing a deep pit, like Golondrinas at 1200ft, think about the weight of the rope. The more weight, the more friction, and the slower you go. As you descend, rope weight decreases and your speed picks up, which can quickly become dangerous. By designing a device that you can pinch (increase) or spread (decrease) friction without changing your rappel device layout, you can continually accurately adjust to descend at a safe speed, from 1200 feet down to 0 feet. They are smooth as butter to use, and do not put a spin on the rope - which is also important to note as many devices will introduce spin...do you want to spiral for 1200 feet and pass out? NOPE!</p><p>Rappel Racks have been designed and redesigned many times over the decades. The Microrack is a 4-bar U frame version which is nice for things under 100-200 feet. There is a rescue rack, rated for rescue loads - you wouldn't cave with this one normally. There is also the Petzl rack (no patent afterall) which is the absolute worst version. Five bars on a short frame means there is zero ability to vary the friction, and on 4 bars it is much to fast for many people. So, it is essentially the rack enshittified, with all the adjustability that makes it great, removed. It would be my last choice of a modern descender. (Petzl made & popularized the bobbin-style descenders, which have their place, but not in this story!)</p><p>Enjoy seeing original Cole racks here: <a href="http://www.verticalmuseum.com/VerticalDevicesPage/Rappel/RackOpenFramePages/JRack0516.php" rel="nofollow noopener noreferrer" translate="no" target="_blank"><span class="invisible">http://www.</span><span class="ellipsis">verticalmuseum.com/VerticalDev</span><span class="invisible">icesPage/Rappel/RackOpenFramePages/JRack0516.php</span></a></p><p>WhaleTails: <a href="http://www.verticalmuseum.com/VerticalDevicesPage/Rappel/FixMultiPages/FixMulti0409.php" rel="nofollow noopener noreferrer" translate="no" target="_blank"><span class="invisible">http://www.</span><span class="ellipsis">verticalmuseum.com/VerticalDev</span><span class="invisible">icesPage/Rappel/FixMultiPages/FixMulti0409.php</span></a></p><p><a href="https://flipping.rocks/tags/rappel" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>rappel</span></a> <a href="https://flipping.rocks/tags/climb" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>climb</span></a> <a href="https://flipping.rocks/tags/geology" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>geology</span></a> <a href="https://flipping.rocks/tags/cave" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>cave</span></a> <a href="https://flipping.rocks/tags/caves" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>caves</span></a> <a href="https://flipping.rocks/tags/caving" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>caving</span></a> <a href="https://flipping.rocks/tags/speleology" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>speleology</span></a> <a href="https://flipping.rocks/tags/karstmas" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>karstmas</span></a> <a href="https://flipping.rocks/tags/adventure" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>adventure</span></a> <a href="https://flipping.rocks/tags/nature" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>nature</span></a></p>