Cattle Hitch vs Eye Splice

[bluefightingcat]

My dinghy metal shrouds have worn out and I plan to replace them with Dyneema DM20. To connect the dyneema to the mast I plan to use a t-eye:



Now I am wondering what is the best way to connect the dyneema to the t-eye. There are two options. Using a cow-hitch like this:



or splicing the t-eye directly into the dyneema eye.

I am wondering which one is more secure. The first option is easier in practice but I am wondering whether the strength of the dyneema will suffer alot because of the bends. Also the second option is permanent but I don't see this as an issue in my case.

[thinwater]

According to Samson (the only reference I have found--Rope User Manual) a cow hitch is about 15% less efficient when joining two rope eyes. They did not test and eye specifically like that, but the geometry is very close.

[Breaking Waves]

Originally Posted by bluefightingcat

I am wondering which one is more secure.

I answered you over on SA.

But I will add here:
(1) you might note that the manufacturer (Blue Wave) shows pictures of this product and they are direct spliced.


(2) I have tested various cow hitch vs direct splice, and while results differ depending on relative diameters, and the cow hitch is generally a bit weaker, but if you are oversizing the stays for creep/stretch, then small strength differences here are really not a critical issue.

As I said on SA, when I did this for my own boat I did a direct splice.

[BillKny]

There is NO WAY on a dinghy that you will be loading up properly sized Dyneema shrouds to anywhere near their breaking strength.

"Properly sized" in this case, means matching the STRETCH of the stainless shrouds, not the breaking strength. Typically, this results in a Dyneema shroud with 3 to 4 times HIGHER breaking strength compared to the stainless wire it is replacing.

Use whichever connection is easier and find something else to worry about!

[bluefightingcat]

Originally Posted by BillKny

There is NO WAY on a dinghy that you will be loading up properly sized Dyneema shrouds to anywhere near their breaking strength.

"Properly sized" in this case, means matching the STRETCH of the stainless shrouds, not the breaking strength. Typically, this results in a Dyneema shroud with 3 to 4 times HIGHER breaking strength compared to the stainless wire it is replacing.

Use whichever connection is easier and find something else to worry about!

When you say "stretch" what do you mean exactly? I have opted for a DM20 dyneema which, if I have understood, correctly has virtually no creep. Is that what you mean?

[Breaking Waves]

another photo - from DM20 data sheet:



Again, direct splices.

[bluefightingcat]

Thanks everyone for the help. Especially Breaking Wave.

[keyway]

Personally I would use the hitch. I could make up the eyes and whip the ends-sitting in a shady spot. I typically over size the braid just for “handiness” and any loss of SWL probably would not be a concern. Plus they would be removable for what ever reason.

[DEAN2140]

Following up on Bilkny, have you considered a buntline hitch? Basically permanent but you said that is not a problem.

[Breaking Waves]

Originally Posted by DEAN2140

hitch?

DM20 retains only about 30% of its original strength in a knot. That's a pretty hefty loss, which can be avoided with a quite simple splice. It might not matter, but personally, I would not take it when the splice is so easy.

[Benz]

Originally Posted by Breaking Waves

another photo - from DM20 data sheet:

Attachment 239035

Again, direct splices.

I don't know where you got this, but those are terrible examples of splices. Those aren't even brummels! It's just the tail woven loosely in and out of the standing part.
Please tell me you know better than whomever did that.

[Breaking Waves]

Originally Posted by Benz

I don't know where you got this, but those are terrible examples of splices. Those aren't even brummels! It's just the tail woven loosely in and out of the standing part.
Please tell me you know better than whomever did that.

Benz, Stay calm, deep breaths

I don't personally consider that 'weave' to be best practice. But it is 'a technique' I have seen used commercially by people who proof test their stuff. They are not intended to be Brummel locks - it is just a form of tucking before the bury. And the photo comes right from a DM20 spec sheet, so people who are reasonably knowledgeable.

[Benz]

Originally Posted by Breaking Waves

Benz, Stay calm, deep breaths

I don't personally consider that 'weave' to be best practice. But it is 'a technique' I have seen used commercially by people who proof test their stuff. They are not intended to be Brummel locks - it is just a form of tucking before the bury. And the photo comes right from a DM20 spec sheet, so people who are reasonably knowledgeable.

Who can stay calm when faced with such atrocity! At least I am taking deep breaths, the better to yell at the computer screen
But seriously, anyone can publish a DM20 spec sheet: it's a fiber a lot of rope companies use. And while that initial tucking might not reduce strength any, it adds nothing but useless length to the splice. It does not add strength, security, not elegance: it just displays an ignorance of how splicing is done.

[psk125]

Would chafe be a concern? Since the load, compared to the strength of the line, is minimal, using the hitch might avoid the point-loading that would happen if the line was spliced to the T. The hitch, spreading the dyneema out over the surface of the eye, might show less wear. If there is wear, either way, the hitches might be easier to replace. How are you going to get the lengths exactly right? What are the fittings at the other end?

[Jolly Roger]

I have just replaced my wire lifelines with 1/4” Dyneema, with spliced ends using CS Johnson Splice Line fittings. Before I finally decided, I had my splices professionally tested on a 40’ foot long commercial test rig. The rope snapped at 7593Lbs., but the splices at both ends held.
As Bllkny states, whichever way the splice is attached will be far stronger than whatever load can be imposed on a dinghy rig. Just watch out for chafe.
JR