Page 116 - Bob Holtzman "The Field Guide to Knots How to Identify.."

Butterfly Coil

Also known as: Backpack Coil, Backpacker’s Coil

A climbing rope of 200 ft. (60 m) or more makes a bulky, heavy load to
carry, and a time-consuming mess if tangled during transportation. The
weight of the Butterfly Coil is carried on both shoulders like a backpack,
and the coil is secured around the waist, which prevents it from swinging
and catching while climbing. But unlike the Alpine Coil, it must be removed
and undone before it can be attached to a climbing harness.

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