On the other hand this little trick has tested at greater than 85% breaking strength and 100% of minimum rate strength in my first few trials, and seems basically idiot-proof. It is based on stuff a sailor has on hand and is as strong as professionally sewn ends. I found 3rd party testing that confirmed these numbers.
Step 1. Double the end of the webbing and thread it through the eye of a chain link twice. The link will need to be 5/16" minimum to have room for both strands. This is grade 30, and any higher grade should do. The shackle must have width for the webbing. I used a 5/16" shackle and 15mm webbing; a 3/8" shackle is required for 1" webbing.
Step 2. Put the shackle pin through the hole.
Step 3. Dress it up. The top strand should be loaded (longer radius) as it is about 10% stronger.
Detail. If the webbing is wrapped around the other end of the shackle (tempting, since a 5/16" bow shackle will fit 1" webbing) there is no space between the chain link and the shackle, causing a shear point. The webbing will shear at about 50-60%; still better than most knots and much easier to untie. On the other hand, if the webbing is wrapped around the pin, as shown, the metal surrounding the pin creates the required gap between the link and the pin, preventing shearing.
There remain 2 potential weaknesses:
- Working loose under cyclic load, just as a bury splice can work loose. A back-up knot or a few stitches solve that.
- Scratching the deck. A chafe guard would solve that.
- Attaching webbing shore anchor rode to anchor points; strong and can be untied after loading.
- Endpoint attachment when testing webbing splices. Yeah, probably just me.