Rode to Anchor Chain Splice. Help Requested.

[Avayak]

I have installed a rope/chain vertical windlass. Purchased the appropriate 8 mm short link chain and can't splice my existing 18 mm 3 strand nylon rode to the chain.
The problem:
Back splice, only two strands will fit through the end link.
Elongated splice: two strands fit through the end link and only one stand fits through the subsequent links.
My boat is an 8,5 ton 35 ft wooden trawler.
I thought I had it figured.
The winch is supposedly suitable as is the chain likewise the 18 mm 3 strand rode. But it don't work!
How do I resolve this? (preferably with existing equipment)
Cheers.





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[Hudson Force]

My quick guess would be that the solution would come with a length of Dynema spliced to the chain and spanning a distance to where the Dynema is then spliced to the three-strand nylon.

[estarzinger]

Originally Posted by Avayak

8 mm short link chain and can't splice my existing 18 mm 3 strand nylon rode to the chain.

yea, 18mm 3 strand is a tight fit thru 10mm chain. I am not surprised you can't get it thru 8mm.

if you want to use that line/chain, there are three solutions

#1 If you make a back or eye splice, you really only need to splice two of the strands thru the chain. This is because you form a spliced loop, which has two 'legs' carrying/sharing the load, and thus has the strength of 4 strands (stronger than the main 3 strand part of the line - you may loose some strength with the chain bend radius but it is still ok). So the technique is to take one of the strands and peel it back a ways, make a nice back/eye splice with the two strands, and then weave the loose third strand into the splice tapering (perhaps by 25% 3 times) it as you go so that it merges smoothly into the splice.

#2 There is a splice that does not seem to have an official name - I have seen it called 'up the chain' or 'shovel'. You take the strands and weave them thru the chain links for a couple feet and then whip them together. In your case you can take strands A & B in opposite directions thru link one, A & C thru link two, B & C thru link 3, and then repeat. The windless guys hate this splice because it has a history of jamming in the gypsies or in the chain pipe. It also brings up a lot of mud. So they all recommend a back or eye splice, but if you decide to go this way, the key is to make sure the strands are all equally tensioned and the chain is straight thru the splice with no links turned sideways.

edit . . . . re splicing in a length of dyneema between the chain and line . . . the trick is to get it to run smoothly thru the gypsy. That's a bit tricky, but it can be done. There is no good 'clever' 3 strand nylon to dyneema splice because the dyneema is so slippery. So there are two alternatives (a) make an eye in the end of the nylon and then a dyneema loop between the last chain link and the nylon eye. It is helpful (for running thru the gypsy) to then sew the eye closed and sew the two legs of the dyneema loop together or (b) an eye in the nylon and a dyneema lashing between the chain and eye. Finish the lashing with a row of at least 5 half hitches and then sew the tail down - to prevent it from slipping/unworking. Both of these may require a bit of fiddling to get to run thru the gypsy. The big question in this case is whether the nylon eye will be too big for the gypsy . . . in which case you are back to solution #1 above.

[svHyLyte]

Take a look at: BlueMoment - Articles No more that two strands per link.

[Hudson Force]

Originally Posted by svHyLyte

Take a look at: BlueMoment - Articles No more that two strands per link.

I like this. It's less complex and more suitable than my first thought.

[Seaworthy Lass]

Originally Posted by svHyLyte

Take a look at: BlueMoment - Articles No more that two strands per link.

This would be my solution too. I do remember I sat up for most of the night the first time my first splice was deployed one blow many years ago . We now carry all chain.

[estarzinger]

Originally Posted by svHyLyte

Take a look at: BlueMoment - Articles No more that two strands per link.

Yea, that's option #2 in my post just above yours. I will say as an aside I am not a big fan of this splice, for three reasons.
(a) the windless manufacturers all recommend against it because it has a history/tendency to jam in rope to chain windlesses.
(b) it brings up quite a bit of mud (why some people call it the 'shovel' splice. (c) in theory both it and the back/eye splice are full strength if perfectly done, but in practice it is rather harder to get all the strands at equal tension in this shovel splice (than in a back/eye splice) and it does not have an 'eye' to split the load between two legs (as the eye and back splices do); so in practice usually quite a bit weaker.

[Hudson Force]

Originally Posted by Seaworthy Lass

This would be my solution too. I do remember I sat up for most of the night the first time my first splice was deployed one blow many years ago . We now carry all chain.

the gypsy

I once had a nylon splice to rode years ago , but like Seaworthy Lass I'm on all chain now. I do have a secondary anchor on 20 ft of chain with an eyesplice and thimble to the nylon rode, but what do I care if it jumps through the gypsy or jams? I don't use it often so I'm right there on the bow to tend to it.

[Weyalan]

If your winch has a single gypsy for both rope and chain, then the gypsy will be sized for the specific chain link size most likely have a recommended size (or range of sizes) for the rope. If the gypsy is sized for 8mm (5/16") chain, it is unlikely that it will be suitable for 18mm rope.

If, on the other hand, there is a gypsy for the chain and a separate part of the winch for the rope, ignore all of the above.

[Avayak]

[QUOTE=Weyalan;1606167]If your winch has a single gypsy for both rope and chain, then the gypsy will be sized for the specific chain link size most likely have a recommended size (or range of sizes) for the rope. If the gypsy is sized for 8mm (5/16") chain, it is unlikely that it will be suitable for 18mm rope.

Good thoughts and therein lies the answer!

I checked the winch makers specifications and found the rope size is 14mm.
The 18 mm had been a web based recommendation by a notable author and was was fine with my old anchor and chain that I hauled by hand. However, there was something wrong with that arrangement because it got heavier every time I hauled it. 😄

Thanks all for your inputs and the trouble you guys went to in responding.

I will head down to local store and buy a meter of 14 mm and check it all works out.

I will first up try the elongated/shovel/ugly splice despite the comments that winch makers don't like it as my reading suggests it is the stronger splice.

I don't think I have wrapped my head around the two strand, two legs giving 4 strands and therefore more strength approach. So I'd appreciate a bit mor clarification.

As I am currently envisaging the suggestion I'm seeing only two strands bending in opposite directions through the end link and doubling back into a back splice.

I've read that a hard bend reduces strength by 50%. So with two strands bent hard, I'm thinking, the strength would actually be reduced to a 1/3 of the rope strength.

I do appreciate the sense of safety to be had in full chain.

The provided link is a good one, thank you.



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[barnakiel]

It is 2 then 1 then one of the 2 remains 1 while the other forms the consecutive 2. That's long.

Can be done.

But 18 mil is pretty plenty vs. 8 mm chain, hence your challenge.

b.

[estarzinger]

Originally Posted by Avayak

I will first up try the elongated/shovel/ugly splice despite the comments that winch makers don't like it as my reading suggests it is the stronger splice.

Certainly your choice, but I will point out that essentially all the windless and rope mfg's recommend or prefer the back splice. Just for instance-
Lewmar (see section 7, pages 10 & 11): http://www.sailkerkyra.com/media/Pro...Manual2005.pdf
Samson: http://www.samsonrope.com/Documents/...UG2012_WEB.pdf



I don't think I have wrapped my head around the two strand, two legs giving 4 strands and therefore more strength approach. So I'd appreciate a bit more clarification. As I am currently envisaging the suggestion I'm seeing only two strands bending in opposite directions through the end link and doubling back into a back splice. I've read that a hard bend reduces strength by 50%. So with two strands bent hard, I'm thinking, the strength would actually be reduced to a 1/3 of the rope strength.

First, the 'standard' back splice takes all three strands thru the chain link (see for instance the two instructions I posted just above). And if you are going with a bit smaller rope you should be able to and should do that.

Second, regarding the strength of eye/back splices, there are two factors to understand. (a) They split the load over two 'legs' of the rope so that each side of the eye carries half the load. (b) The strength is then decreased by the bend radius, but in a three strand splice the bend radius turns out to not be that small. That is because you unlay the three strands, and they (each strand) then spreads out over the chain link, so the bend radius is not chain diameter to rope diameter, and it is not even chain diameter to strand diameter, it is more like chain diameter to fiber diameter and that is a reasonably big radius which does not weaken the rope much at all (10% reduction). I have actually pull tested this with a load cell, and it can a bit worse than fiber diameter to chain diameter (it depends on the specific chain and rope and splice), practically speaking lets say around a 20% reduction.

So if we take those two factors together a full three strand back splice will essentially NEVER break at the chain bend (unless it is allowed to chafe there, which it should/will not if the splice is properly made), because it is 2x strength * 80% = about 160% of the rope. A partial back splice using only two strands will be 4/3 * 80% = 107% of the main rope.

Now the ugly splice will at the very best be 100% of the rope strength, and if you do not get all three strands exactly evenly tensioned up, then perhaps only two strands may carry all the load and it will only be 66% of rope strength.

I have actually done pull/load testing which confirms all this.


That all said . . . . if you are careful and do a neat splice any of the various options we have discussed will probably be ok. Your anchor is likely to let go well before any of these splices come apart.

........

[Jammer Six]

The book you need is available as an e-book.

It's called "The Complete Rigger's Apprentice" by Brion Toss.

It describes exactly the splice you're looking for, and explains why only two strands through the first link isn't a problem. It describes in detail how to make the splice you want.

In a previous life, I rigged for cranes, and the Toss book is easily the best book I've ever read about rigging.

[Avayak]

Thanks Jammer Six. A good book is a good book even if it takes a peculiar reader to appreciate how interesting knots and such things are. I will certainly get a copy on your recommendation.


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[Avayak]

Originally Posted by estarzinger

........

Thanks for such a fascinating and informative reply.

I followed up your included links. Thank you.

It's a woman's and thinking mans right to change their mind .... I'm going with the back splice!!! ;-)

I bought my 1 mtr of cheap 14 mm rope and did a trial test. I'm more than happy with the result. See photo.

I laid a length of the 18 mm along side. Pretty clear why 18 into 8 don't go. However, the 18mm has been running perfectly well in the gypsy so when I look at the back splice, which is still fresh and unstretched I feel confident that it too will go around the gypsy like the manufacturer intended :-) Strange that!



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