Introduction

While researching this article I asked Google who invented the soft shackle. The answer included "someone named Edwards." Surprise - that someone is me.

Of course, the truth is more complicated. The soft shackle did not spring fully formed from one person's imagination. It has roots going back centuries, was commercialized in modern form by companies like Kohlhoff and Colligo, and then refined by a handful of sailors, riggers, and DIY experimenters - myself included.

Line-based shackles have deep roots

Line-based shackles have been around for hundreds of years. The basic idea is simple: form a loop in one end of a line, tie a stopper knot in the other, and pass the knot through the loop. When the line is put under load, the loop tightens around the knot and holds fast. The earliest published example I can point to is in The Ashley Book of Knots. Entry #3180 shows exactly this: a fixed eye and a button knot. Under tension, the button jams in the eye and cannot slip out.

Modern beginnings: Kohlhoff and Colligo

The oldest Dyneema version I have found is the Kohlhoff soft shackle. It differed from the older versions in that the eye was an expandable noose that would tighten to hold the button knot, in this case a diamond knot. While strong and secure, the fact that the line from the noose to the diamond were open gave some people the feeling that the shackle was not secure. The thought was that one of these strands could get snagged and the noose would open and release the shackle. I share those fears even though I think the fear is irrational.

That impression of insecurity was solved by Colligo Marine with their version, often called the "Softie." In this design, the eye strand is buried back into the body of the shackle, creating a cleaner look and reassuring users that the loop could not slip free. Colligo's soft shackles were widely commercialized and remain the style you are most likely to find in marine stores today.

Opening it up to DIY and the Better Soft Shackle

Colligo published a video showing how their soft shackle was made, but it left out key details. With some experimenting I filled in the missing steps and then published full instructions so that anyone could make one. That write-up spread quickly. Sailors who had never considered making their own started building them, and soft shackles went from being a specialized commercial product to a do-it-yourself project.

Colligo was not pleased. At one point they told me I had "spoiled the market" because once the details were out there, people realized they could make soft shackles at home for a fraction of the retail cost. I understood their frustration, but I also felt it was important for the sailing community to be able to make and use these tools. Publishing those details opened up soft shackles to a wide audience of DIY sailors who otherwise might never have tried them.

As more sailors began making their own, a practical issue showed up. The Colligo version worked, but once it had been used under load it could be very difficult to open. Colligo solved this by adding a small pull line to help spread the eye apart. I took a different approach.

My solution was a hybrid I called the Better Soft Shackle. It blended the best features of the two main styles: it was as easy to use as the Kohlhoff version, where the noose could be slipped on and off without fuss, but it also had the security of the Colligo version, where the eye strand is buried and locked inside the shackle body. By combining those elements, the Better Soft Shackle avoided the frustrations of either design on its own.

When Grog, the author of Animated Knots, asked if he could make an animation of my version, I agreed on the condition that he gave me credit. He did, and on that site it became known as the Edwards Soft Shackle. Outside of Animated Knots - and more recently in some Google search results - the name has not really stuck. Even so, this hybrid design, and the refinements that followed, are now widely used today.

Sailing Anarchy and the push for a stronger design

On the Sailing Anarchy forums, a long thread on knots and splices became the proving ground for the next big step in soft shackles. A contributor who went by Estar built a dedicated test bench with a hydraulic ram and began publishing systematic break tests of knots, splices, and shackles. I joined in under my username allene222, sharing comparative tests of my own. My method was simpler: I would put a soft shackle against a length of spliced line and pull until one broke. If the line broke first, I knew the shackle was stronger than the line. If I put two shackles of different designs in series, whichever survived was the stronger of the two.

Those tests confirmed what I had been seeing on my own: soft shackles almost always failed where the line entered the stopper knot. That weak point became the focus. If it could be fixed, the shackle could be made much stronger. My solution was to feed the tails back down through the knot and bury them inside the standing part of the line. It worked - the resulting shackle tested stronger than anything we had before. But it introduced a new problem: the modified diamond knot I used could collapse under heavy load.

That is when the rigger Brion Toss suggested replacing my collapsing knot with a different stopper: Ashley's #880 from The Ashley Book of Knots pages 162-163. The #880, sometimes called a button knot, solved the collapse problem and gave us what came to be called the Stronger Soft Shackle. It combined my idea of feeding the tails back into the line with Brion's substitution of a non-collapsing knot. The result was indeed stronger, though at a price - the button knot is notoriously hard to tie. Even with instructions, it took me multiple attempts to make one correctly.

The Stronger Soft Shackle proved itself in testing, but its difficulty to tie limited how widely it spread among sailors. Even with good instructions, most people found it too finicky to make reliably, and the simpler Better Soft Shackle was usually the more practical choice. Brion remained an advocate, and the design did find a home in other fields. Off-road drivers and recovery crews adopted it enthusiastically, since they often use Dyneema lines so large that simply going up a size is impractical. I bought one of these commercial recovery shackles made from 1/2 inch Dyneema. The knot is two inches across, the shackle weighs a quarter of a pound, and it could easily lift my entire boat while still maintaining about a five-to-one safety margin.

It is worth noting that most Stronger Soft Shackles are usually built using the Better Soft Shackle loop construction - the key difference is the substitution of the ABOK 880 button knot with the tails fed back and buried. That detail eliminates the traditional weak point at the line entry to the stopper knot. By doubling the line at that entry, the strength at that spot is no longer the limiting factor. The result can be roughly twice the strength of the line itself, and the failure tends to move elsewhere, typically to the eye. The image to the left is of one I purchased from Temu (before the tariffs).

Recommendation and wrap-up

After all of this, my preference remains the Better Soft Shackle. It is easier to tie, easier to use, and for me the slightly larger diamond knot simply feels more secure than the button knot. For most sailors and DIY riggers, that combination of simplicity and reliability is the right choice.

There is another reason I lean toward the Better Soft Shackle. Many sailors use soft shackles to attach sheets to the clew of a sail. If the shackle is tied too small, the thin line of the shackle can cut into the eye of the yacht braid, moving the weak point to the sheet itself. A properly sized Better Soft Shackle avoids that problem.

That said, there are times when the Stronger Soft Shackle earns its place. When a shackle must secure metal to metal - for example, through the link of an anchor chain - the extra strength of the ABOK 880 button knot is valuable. If you have the patience to master the knot, it is the strongest option available.

On my own boat, I do not use standalone soft shackles much anymore. Instead, I rely on line shackles and variations of them. They are faster, easier to handle in practice, and suit the way I sail. That will be the subject of a separate article next month.