Page 605 - Bob Holtzman "The Field Guide to Knots How to Identify, Tie, and Untie Over 80 Essential Knots for Outdoor Pursuits"

83. Sheepshank

Also known as: Dog Shank

The Sheepshank is useful to shorten a line. For example, when lashing a
tarp over a load on a trailer, a Sheepshank can be used to take up any
excess length of rope, so that only a sufficient length of working end has to
be pulled through the purchase of a Trucker’s Hitch. It’s also a good way to
bypass a weak or worn section of rope if you don’t want to cut it out.

Instructions

1. Make three underhand counterclockwise crossing turns.

601