ISC Rope Wrench

The ISC Rope Wrench is a friction device that sits above your hitch and turns a standard friction hitch into a practical single-rope (SRS) climbing system. The rope wrench adds the extra friction a hitch needs on a single line and keeps it tending smoothly as you move.

Why a rope wrench

On a doubled rope, a friction hitch has the help of a 2:1 system. On a single stationary rope, a hitch alone usually grabs too hard to release smoothly or runs too fast to control. The ISC Rope Wrench solves that by bending the rope through a short channel above the hitch, adding friction there so the hitch only does part of the work.

The result is the hitch feel climbers know, on a stationary rope that can be anchored at the base or to a big canopy limb. It made SRS practical for many arborists before fully mechanical SRS devices were common.

The ISC Rope Wrench is one of the most widely used SRS friction devices in tree work, and many climbers learned SRS on it. ISC is a UK-based maker of climbing and rescue hardware.

Tethers and setup

The wrench connects to your hitch carabiner with a tether. A flexible tether lets the wrench move with the rope, while a rigid tether keeps it aligned and makes tending easier when you are not weighting the system. ISC sells the wrench with or without a tether; choose based on how you climb.

Use the hitch cord and hitch ISC recommends for your rope diameter, and tie the hitch below the wrench as shown in the instructions. A micro pulley below the hitch helps tend slack. Test the full system low before climbing.

Hitch choice matters. Many climbers use a Distel or VT hitch with the wrench. Too few wraps and the system slips; too many and it will not release. Adjust a little at a time and test.

On the job

SRS with a rope wrench shines on tall trees and big removals: you ascend quickly with a separate ascent system, then switch to the wrench for work positioning and descents. Pair it with a Petzl Ascension or other ascender for fast climbing.

Compared with fully mechanical SRS devices, a rope wrench system is lighter and familiar, but hitch cords wear and need regular replacement.

The rope wrench can also be used for work positioning on a base-tied line, which makes it easy to retrieve the rope from the ground after the job. Plan your anchor carefully, since forces on the anchor are different from MRS.

Inspection and wear

The rope rubs the wrench's wear surfaces, so check them for grooves, and replace wear parts according to ISC guidance. Inspect the tether, hitch cord, and carabiners every climb. Life-support gear must meet the applicable standard (ANSI Z133 and the manufacturer's instructions), be inspected before every climb, and be used only by trained climbers.

Clean sap and grit from the wrench regularly, and check the tether for wear, especially at connection points.

If you are new to SRS, have a qualified trainer check your setup and watch your first climbs.