Dyneema Double Eye
- Thread starter FlimFlamII
- Start date
Much as I like Dyneema eye splices that's a tricky spot. The standard guidance is to bury about 50x the rope diameter, and you won't have the length for that with only about 6" between the eyes. If you use 1/8" dyneema and a 3" bury off each eye you'd only have about a 24x bury. You could maybe have the tapers overlap and get 4" bury on each, which gets you to 32x bury, but still not very good with slippery dyneema.
Maybe instead of the double eye you make one continuous loop? That could be spliced like
That is, I think, a ingenious solution. Make the loop, slip it into the sleeve, and if the OP wants eyes, just hold them in place with wraps of splicing twine. One splice, and no need to do it with the rope inside the sleeve.
Or couldn’t you just use a dyneema lashing and call it a day? Maybe not elegant but it should work.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,214
The loop spliced dyneema line is certainly a consideration. For the specific application I would have the loop tested to establish the strength of the splice. I have used buried dyneema line on my gates safety gates. They are going on 6 years of exposure. No whipping was used, just the Chinese finger torture grip of a line inside another line. Line shows no deterioration. I'll take a photo next week when I am on the boat. For the application one could use a soft shackle. I have tested these. 1/4" SK62 Amsteel line when tied into a soft shackle has a breaking strength of 10K pounds. This would exceed the force requirement for a sail attachment. I suspect the force for the application on FlimFlam might be about 300-500lbs. In such a case you could use a 1/8" or 3/16" line and have 300% plus safety factor.
From my soft shackle test reports.
From my soft shackle test reports.
| Description | Min Strength | Avg Strength | TESTED Break Strength | SS Wgt |
| 7/64" (2.5 mm) Amsteel Blue | 1,400 lb | 1,600 lb | 2,800 lb | 0.0105 lb |
| 1/8" (3.0 mm) Amsteel Blue | 2,300 lb | 2,500 lb | 4,600 lb | 0.0175 lb |
Loop. Double eye (some call them rabbit ears or dog bones) are weaker and harder to make. Then slide it inside 1" tubular webbing. Easy peasy.
You could slide 15mm webbing or a Dyneema chafe sleeve (two short lengths) on to the rope before splicing, to provide wear protection. Or thimbles and siezings. The need for protection depends on what it is mated to; smooth and big, or small and rough.
You could slide 15mm webbing or a Dyneema chafe sleeve (two short lengths) on to the rope before splicing, to provide wear protection. Or thimbles and siezings. The need for protection depends on what it is mated to; smooth and big, or small and rough.
My boat has a dyneema continuous loop with a metal ring at one end and an eye with thimble on lower end. Works well. The picture also shows a soft shackle used to attach the ring to the sail.
This is similar to what I made with dyneema, a continuous loop is very easily done.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,214
This is a soft shackle made using 1/4” Samson Amsteel. They can be made and length desired. For the task on the boat in the picture I think the 1/8” dyneema would be more than adequate with a 300%safety factor. There is no risk that the buried line will slip when using the soft shackle knot system when compared to the buried loop design.
A 12” loop soft shackle cost approximately $3 usd in materials.