SRT, DRT, DdRT, DmRT, SRS, MRS, WTF?
Technical tree climbing revolves around two primary principles, using either a stationary or moving rope system, depending on the type of tie in.
(SRT) Single Rope Technique, also known as Stationary Rope Technique is associated with a stationary climbing line secured with a canopy or a basal (ground based) tie-in-point. The rope always remains fixed at the anchor point when the climber ascends or descends. When a climber is using two separate SRT systems which is very popular for many climbers, it technically becomes (DRT) Double Rope Technique.
(DRT) Double and (DdRT) Doubled Rope Technique are often confused, but most of the time refer to a climbing line that goes up over a limb, and back down to a climber. If one is splitting hairs, the difference between double and doubled is how DRT refers to climbing on two ropes with separate anchor points, whereas DdRT refers to a single moving rope, doubled over a limb with the climber advancing on one side of the two legs.
(DdRT) Doubled Rope Technique is similar to tightening a lasso, as one of the rope’s two legs feeds through a progress capture device, the other leg’s termination end attaches onto the climber. Both legs of the rope move, but only one leg feeds through the climbers progress capture device. Since the climber controls both ends of the line at all times, easy retrieval is possible.
DRT is described as two separately anchored lines or two immobilized legs of one line. A climber can use a friction hitch and a foot-locking method to ascend using two ropes together, or by advancing on two ropes independently. Another variation of DRT is described as using SRT on one of two separately anchored ropes, while connecting to another progress capture device installed on a second stationary rope, as a fall-arrest backup measure.
DdRT and DRT describe two distinctly different climbing methods, even though lots of educational material still incorrectly uses the DRT acronym to describe DdRT.
(DmRT) Doubled moving Rope Technique is yet another entirely different climbing method, using two legs of a single climbing line doubled, or looped, around a limb or fed through an anchored pulley. The rope moves back and forth in a sawing like manner. A climber using a dual-ascender device, combined with two foot ascenders is able to ascend up a climbing rope and gain a 2:1 (MA) mechanical advantage. Conversely, on DRT the climber can use a dual hand-ascender and a footlocking technique to ascend on two separately anchored lines. On DdRT the climber only advances on one, not both legs, of the doubled line. This requires using only one of the dual hand ascender’s two progress capturing rope grabs.
The following video uses a Dualcender with a traditional DdRT-like moving rope canopy tie in. Notice how when either leg below the device is pulled down, the device ascends up the rope.
In this example, a climber uses two Petzl ZigZags on DmRT. The climbing line is passed through a canopy anchored pulley to minimize the rope’s friction when moving back and forth. The climber advances up the two ropes simultaneously by using two foot ascenders in an alternating way, while the dual-ZigZags capture the upward progress. On DmRT the climber can easily transition between a 2:1 MA and a 1:1 MA, when managing the two legs.
Thanks, Richard & Karolina for this beautiful demonstration video!
DdRT gives the climber a 2:1 MA, but only advances one foot for every two feet feeding through a progress capture or multicending device, while the termination end of the other leg is anchored onto the climber. On DmRT, while neither leg is anchored, the climber also gains a 2:1 MA, but advances on both legs with two progress capture devices, one for each of side the rope’s two legs. This notable difference warrants giving DmRT a different acronym than DdRT.
In this video, NASA demonstrates another variation of DmRT. The concept also works in zero gravity, as well as here on earth. In fact, this sort of climbing/hauling system can be useful in certain situations.
This illustration shows a DmRT hauling system, adapted into an assisted climbing rig. In the illustration the 2:1 MA is lost when the climber’s weight is transferred from the rope’s two legs, onto the respective sides of the seesaw, or through some other ground based augmentation to facilitate the rope’s up and down motion.
DmRT may not be very efficient for unassisted climbing, but it could be used more practically in an assisted tree climbing or hauling system scenario. This then gives rise to potentially new climbing gear designed specifically for this purpose. Such gear may eventually include a dAkimbo, or some sort of a double rope multicender.
Now that we’ve identified at least four distinct types of climbing methods, one idea may be to simply change DdRT to MRT and leave DRT and SRT unchanged. Because DRT & DdRT are inherently conflicted acronyms. NiceGuyDave @ Wesspur clarified the differences and proposed SRS and MRS, thereby eliminating or bypassing the use of the DRT and DdRT acronyms, in the traditional sense. This makes a lot of sense to many, but it may limit innovation when other variations in viable climbing methods are possible, as well.
As more attention is given to this issue, a clear path becomes more evident. There needs to be a consortium and agreement in order to achieve consensus, at least among the primary players, including major equipment dealers, the ISA and similar organizations.
When we combine the two concepts concerning the use of rope legs, further identified with the act of remaining stationary or not, it alleviates a lot of confusion and improves clarity in a uniform manner, as follows:
SSR = Single Stationary Rope Technique, versus: SRS & SRT
SMR = Single Moving Rope Technique, versus: MRS & DdRT
DSR = Double Stationary Rope Technique, versus: DRT
DMR = Doubled Moving Rope Technique, versus: DmRT
Replacing vaguely descriptive acronyms can address the methods more descriptively and provide a broader, more universally accepted definition. The fact remains, it all comes down to whether there are one, or more, stationary or moving ropes involved.
In conclusion, most tree climbers will probably continue to refer to SRT and DdRT and/or adapt to using SRS and MRS in general terms. At some point the tree climbing community will hopefully agree upon more descriptive and less confusing acronyms to describe a wider array of climbing methods.
Happy climbing. Be Safe!