Single Rope Technique (SRT)

Purpose and Description:

This document is intended to provide a basic curriculum and guidelines for a Single Rope Technique Basic Course. These guidelines are not intended to prescribe correct or incorrect methods of climbing by independent climbers - rather they are intended to describe the minimum understanding of an SRT Basic Course graduate. This is a living document subject to periodic revision as determined by the GOTC community.

Glossary of terms

SRT - Single Rope Technique where a climber ascends or descents via a single fixed rope.

TIP - Tie-in-Point

PPE - Personal protective equipment, such as carabiners, harnesses and helmets.

Safety Check - the process a climber uses to ensure the climbing system is set-up and connected correctly. (e.g. BACK check)

Two knot* Texas system -  Two friction hitches (e.g. prusiks) are used to secure the  climber to the rope. The climber stands using a foot lock or foot loop attached to the lower hitch (or a separate foot loop using a third friction hitch) and slides the topmost hitch upwards - capturing the climber’s progress.  The climber weights the upper hitch, and slides the other hitch(es) upwards, before repeating the cycle. * Sometimes called a Three Knot Texas System, the additional friction hitch is used for a foot loop.

Texas system using mechanical ascenders - Similar to the two knot Texas, except the hitches are replaced with mechanical ascenders. In this case the foot loops are attached to the lower ascender. As with the two knot version, both ascenders are attached to the climber. * GOTC recognizes that some experienced climber prefer to forgo the life support attachment between the lower ascender and the climber’s harness, which might provide the climber with some benefit during particular climbs, although it increases the risk. GOTC firmly believes that climbers in a Basic SRT course should be taught to use tethers on both ascenders.

Yo-yo (also known as RADS for "Rope Ascending Descending System") - A mechanical ascender with a foot loop is attached to the climbing rope. An autolocking belay/rappel device is attached to the climber’s harness at the waist, below this ascender. The brake strand (as it exits the belay/rappel device) is routed up to the ascender and redirected back downward (usually through a carabiner or pulley). * GOTC recognizes that some experienced climber prefer to forgo the life support attachment between the ascender and the climber’s harness, which might provide the climber with some benefit during particular climbs, although it may increase risk. GOTC firmly believes that climbers in a Basic SRT course should be taught to use a tethered ascender.

Eccentric Cam Ascender (aka frame loaded ascenders) - the most common type of mechanical ascender used in tree climbing, utilizing a toothed eccentric cam. The climber or load is attached to the frame. The teeth of the cam catch on the sheath of the rope, engaging the cam, which pin the rope against the frame of the ascender.  *CMI Ultracenders, and Jumars are well known examples of this ascender design.

Cam loaded ascender (aka Type1 Lever Ascender) - A type of mechanical ascender less common in tree climbing than an eccentric cam ascender, although small ascenders of this type are often used on fliplines or positioning lanyards. The climber or load is attached directly to a Type 1 Lever cam (effort - pivot - load) and pins the rope against a channel in the frame of the ascender.  *The Gibbs Ascender and Petzl Rescuecender are well known examples of this ascender design.

Risk management

All courses shall require the participant to pass a final written exam reviewing key course material, as well demonstrate practical competency in the course material.

The instructor or school shall:

  • Register students and maintain a record of the student’s performance in the course.
  • Carry liability insurance specific to Tree Climbing.
  • Require signed document(s) from each student for:
  • Release from liability
  • Assumption of risk

Record of student's participation may be as basic as:

    Date     Course     Name     Passed?

e.g. 1/1/2010 Basic SRT Alice Lou Passed

Assumption of risk and release from liability are legally distinct concepts, but may be (and are often) incorporated into one document.

Course participants shall be competent in DRT climbing, including basic knot tying, use of PPE, tree assessment, tree entry, shout calls, safety checks, etc. Instructor shall discuss how SRT tree climbing differs from DRT tree climbing.

It is the responsibility of the instructor to assess a student’s competence in DRT climbing. Competency in DRT will give climbers many more options in the case of an emergency and more ways to get themselves and their climbing partners out of any trouble.

The student(s) must be briefed on safety guidelines:

  • When ascending, climbers must be attached to the rope with at least two different life-support attachments.
  • Climbers must not climb above the anchor point or limb.
  • Climber must descend in a controlled manner without excessive speed.
  • Alcohol, prescription and recreational drugs are not appropriate in SRT or DRT tree climbing.
  • Remove or secure any items that can become tangled in climbing systems.
  • Tie back long hair
  • Wear appropriate clothing and footwear for the weather and activity - plan ahead!
  • Respect fatigue
  • Ask questions when in doubt.

 Additional ethical guidelines:

  • Respect other climbers, the instructor, the tree and the surrounding environment at all times.
  • Practice good wilderness ethics - pack it in / pack it out.
  • Intentional damage to any tree is never appropriate.

All equipment used in "life-support" applications shall be equipment manufactured specifically for use in accepted rope-assisted climbing activities by reputable, well-known manufacturers, and shall be used in accordance with manufacturer's recommendations and industry practice.


Instructors will display and explain the functions and limitation of SRT specific equipment. This includes, but is not limited to:

Mechanical Ascenders

Screw links

"Autolocking" rappel device suitable for use in a Yo-yo system.

Additional rappel devices

At lease one assisted line placement device (e.g. pole-mounted sling shot, crossbow, hand-held sling shot, compound bow, etc.)

Examples of "autolocking" rappel devices: Petzl Grigri, Petzl I’D, Edelrid Eddy.

Should include instruction on how to lock off the device. Examples of additional rappel devices:: Figure-8 descender, tube style belay device, bobbin, mini-rack, Pirana.

Additional curriculum topics:

  • How to choose and assemble a set of personal SRT gear;
  • Appropriate sources for obtaining SRT climbing gear;
  • Inspection, maintenance and storage of SRT climbing gear.
  • Some rope is suitable for SRT, but unsuitable for use in a traditional DRT system. SRT ropes are of smaller diameter, "static" or low-stretch in construction, often not designed to hold DRT knots/hitches properly, although some ropes are appropriate for both DRT and SRT.


Climbers shall be instructed on installation of Aerial / Limb Cinch and Ground / trunk-tie anchors.

Limb cinch curriculum includes:

  • forming the cinch using only a loop knot
  • forming the cinch using a loop knot in conjunction with a screw link.
  • pull downs using rope or throwline

 Example of an appropriate loop knot: figure 8 on a bight.

Curriculum for ground-tied anchors includes:

  • Appropriate life-support termination.
  • Discussion on load mulitplication at the TIP

Examples of appropriate ground anchor termination: 

  1. wrap 3-pull-2 webbing anchor attached to a figure 8 on a bight using a screw link, 
  2. wrapping the rope twice around the trunk and cinched using a figure 8 follow through, 
  3. two half-hitches secured with a timber hitch and overhand backup (the tail of the timber hitch should have at least three wraps in direct contact with the tree).

Curriculum for anchors includes discussion on potential drawbacks of using carabiner(s) in conjunction with a loop knot.

Downsides of carabiners includes potential cross loading, potential unlocking and opening of gate while unmonitored.

Ascending systems

Students are taught how to:

  • attach to rope
  • ascend
  • down climb
  • changover to rappel
  • use safety checks before ascent or descent

Using following ascending systems:

Two Knot Texas System

Texas System using mechanical ascenders

Yo-yo with a tethered ascender

Should include a discussion of how safety checks differ between SRT and DRT.


In addition to use of specific rappel devices, students are taught general rappelling technique:

  • basic rappelling guidelines (never take the brake hand off the rope, watch for loose hair and clothing, avoid overheating the device, check that the device functions prior to removing backup connection)
  • methods for backing up a rappel
  • to check that the rope reaches the ground or to tie a stopper knot in the end of the rope.
  • how to provide a bottom belay (fireman’s belay) to another climber.
  • how to lock off a rappel device
  • techniques for adding additional friction.

E.g. prusik attached to the leg loop below the device or leaving the ascender attached and moving it down periodically during descent on a yo-yo system.

Examples of techniques for additional friction - rerouting the rope through a carabiner attached to a leg loop, bringing the brake strand against the hip, or device dependent recommendations such as double-wrapping a figure-8 descender. 

Transfers and multipitch climbing

Course shall cover how to perform transfers from:




without direct support from the tree (mid-air transfer), or use of an additional rope or lanyard.

Additionally, instructors are encouraged to teach how the transfer process may be different while standing or sitting on a limb.


Student shall perform a rescue in the following circumstances:

Student uses an SRT system to rescue a victim on a DRT system.

Student on SRT rescues a victim on SRT, using the one rope. 

The intent of the rescue guideline is to expose the student to SRT rescue methods and requirements, through two hands-on rescues. Students are encouraged to take a rescue-specific course for more in-depth study of rescue skills, equipment and techniques.


Contributing Instructors

Out On A Limb Tree Climbing

Tree Trek Exploration

Tree Climbing Colorado

Dancing with Trees

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