Page Contents:
Overview
A Moving Rope System (MRS) describes a climbing system and method which involves a rope which is routed over a tree crotch and as folded (doubled) over a tree crotch and one end of the rope attached to the climber directly and the other side is attached via a friction hitch or device. Related pages:
DRT is an obsolete term
MRS (Moving Rope System) is the current and preferred term for this climbing method. The acronym DRT means different things to different audiences and has caused confusion for years, particularly the meaning of the letter D and whether it means Double vs Doubled. Background:
- “Double” means two. In Mountaineering and Rock Climbing, the use of two independently anchored ropes is a common practice, thus Double Rope Technique = DRT.
- “Doubled” rope methods were pioneered in the arborist industry, where the techniques use one rope (not two) which is “Doubled” or “folded over” a tree crotch – just like a blanket or tarp is doubled when it is folded.
- In order to reduce confusion, the arborist industry attempted to use the acronym DdRT (Doubled Rope Technique), however this was short sighted because a doubled rope can be climbed two ways: as a Moving Rope System (MRS) or as a Stationary Rope System (SRS). For example, using a single friction hitch around both strands and a footlocking technique to ascend is a SRS, not an MRS.
Conclusion: MRS is the preferred term, but don’t be surprised that some folks are resistant to change.
JRB’s Position
JRB used a Moving Rope System for 10 years before moving onto other methods, due to their advantages over MRS. In general, JRB does not recommend MRS as a rope climbing method for a a saddle hunter except in special situations, described below. Thus, there is (currently) no page for an MRS/DRT system on the website. If a user wants to build an MRS system, consider building or modifying a Universal System:
Pro’s and Cons
When comparing MRS/DRT to other rope based methods, consider:
Pro’s
- Minimal sag/setback. Because it is a 2:1 Mechanical Advantage system, while climbing, there is always tension on the main bridge carabiner. Thus, our saddle cannot sag. If our saddle is heavy or not firmly attached to our hips, this can be a problem for other methods like 1:1 SRT and DSRT.
- Simplest system: one friction hitch and a rope is all we need. (a 2nd carabiner and bridge are recommended). If necessary, we can even construct a DSRT system with just a rope (using Blakes Hitch).
Con’s
- Inefficiency due to Friction: Because the rope moves in the crotch, there is a significant amount of loss in the system. Overall, we use more energy to climb than in other methods. A “friction saver” device can be used to reduce friction, but the practicality of doing so for a saddle hunter introduces undesired complexity and time.
- Lack of progress capture. Most arborists climb an MRS without progress capture, requiring that they manually capture progress while holding tension. This can be mitigated in the systems described below.
- Inefficient ascent techniques: Most MRS climbers use inefficient ascent techniques. As per the video below (Self Tending Arborist System), this can be mitigated and remove the need for hip thrust or wrapping the rope around our hands (needing gloves) when executing MRS.
- Rope wear due to friction: Because the rope moves in the crotch, the rope takes on a significant amount of wear and will have a reduced life expectancy.
- Noise due to friction: It will not occur on a first time climb, climbing the same tree multiple times can cause the rope to burn into the cambium layer of the tree, which can cause a creaking noise during ascent and rappel.
- Pace of ascent: Because it is a 2:1 system, we ascend at approximately half the rate of a 1:1 system like DSRT.
Longhorn Agile System
Below, JRB demonstrates a self tending MRS system using the Longhorn Agile Hitch. Overall, JRB does not recommend MRS for able-bodied saddle hunters unless they have a physical limitation which prevents them from using DSRT or SRT, which are faster and more efficient.
Blake’s Hitch System
If all we have is a (flexible, bendable) rope, we can create a system with a Blake’s Hitch system. See video: