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Topic: Dyneema Shrouds and Splicing (Read 4553 times)
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Claus Riepe
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Tony,
yes, the wrong one is wrong and the one with the question mark is the correct one.
A bit tight when you have to get the hard eye of the shroud end you have done first through the strands, but it does work. The needles are so smooth they help widening the gap in the strands.
The hollow needle splicing tool is also great for burying the loose end inside the standing part, you just tuck it in and slide it on inside the standing part, loose end in tow.
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Michael Rogers
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Hi Guys. What is the problem with clapping on a seizing, either using a thimble or to form a small \\\'naked\\\' loop? I\\\'m not scoring points here, but asking because I\\\'d like to know! It\\\'s my preferred method with braided rope anyway, and if you take a bit of care, use fine whipping twine and put on the extra frapping etc turns (my copy of \\\"Marline Spike Sailor\\\" hasn\\\'t surfaced yet after our move, and I can\\\'t remember all the jargon), the result is v neat and v strong. Isn\\\'t it?
I got some grey plaited 100% Dyneema from Mailspeed Marine yesterday (LOVELY stuff in the slippery stakes!), and I\\\'ve tried a seizing. It works fine, and round a thimble there would be no kinks or v small radii to weaken the rope. As a hitch a constricter knot also seems to hold, especially if one uses two riding turns.
On the subject of breaking strains, isn\\\'t it true that for most uses in our kinds of sailing, ropes parting because of overload is almost never a practical issue? (Shrouds are an obvious exception with special considerations, and I know this is where Claus came in in the first place, until I caused a diversion!) Halyards and sheets are the thickness they are for ease of handling, not because they need to be anything like that strong. The Newlands were entirely logical in this respect with their practical attitude to the jib sheet once the loading had been greatly reduced by using club booms on the Storms etc.
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Tony
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Hi, Michael.
Nothing wrong with a good, tightly whipped seizing, so long as the whipping twine bites deep enough into the material in use to make sufficient friction, thus keeping it all together. (As you point out, the frapping turns are important in this respect).
The only problem with Dyneema is that it is both hard and slippery, making this difficult.
If it holds, great, but the amount of grip the whipping has on the Dyneema can only change for the worse.
The beauty of the splice that Clause uses is that as the tension increases the splice grips ever harder! With enough bury there is also a much larger area of frictional surfaces in contact – which is why splices of all kinds are generally preferred to the equivalent knot or seizing.
Why do I still use a scaffold knot when making a hard eye?
Three reasons. No tools required; it takes only seconds to tie; I trust it to work.
However, where it REALLY matters (eg anchor chain to warp) I take my time and use a splice!
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Michael Rogers
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Tony, all points taken with thanks. I must add a scaffold knot to my repetoire.
Emphasising that shrouds are a special case (I must look up the etymology, if it is known, of the use of the word shroud in this particular nautical context), in other rigging situations I still think a sense of proportion is needed - horses for courses, to mix a metaphor or two. If Dyneema is ten times stronger than polyester, and putting a bowline in it halves its strength, it is still five times stronger than polyester! In any case, as I indicated before, my personal use of Dyneema will be limited and specific, and I doubt if sudden failure of a luff-hauling parrel would ever be catastrophic in its consequences
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Julian Swindell
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Question for Claus. How do you finish off the other end of the shroud, down at the bottom? I think they generally use a modern deadeye system. How do you fix to that, as you cannot form another eye in the other end the same way can you?
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Claus Riepe
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Question for Claus. How do you finish off the other end of the shroud, down at the bottom? I think they generally use a modern deadeye system. How do you fix to that, as you cannot form another eye in the other end the same way can you?
Julian, you can have hard eyes on either side, surprisingly you can widen up between the strands enough to squeeze the hard eye done first through. Though, I think the hard eye is not even necessary. The next shrouds I\\\'ll do I will leave the hard eyes out. Good luck, C. |
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Julian Swindell
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I have just got some dyneema shrouds for my BayCruiser and I am intrigued by the whole idea of non-metallic rigging. Regarding the splicing kit at the start of this thread, the special splicing tools are just locking forceps, which you can get from most toolshops eg http://www.axminster.co.uk/product-Electro-Locking-Forceps-20071.htmHas anyone used the modern deadeye system rather than hard eyes and lanyards or rigging screws? http://www.precourt.ca/Or the dyneema soft shackles, which seem a good idea but amazingly expensive. £24 each on ebay! BTW I did a google search on dyneema shrouds and it came up with this threaad as the first hit! |
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Julian Swindell
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Following on from the last, have a look at this mind boggling way of doing an eye splice in dyneem when you can only get at one end of the rope. I think I can just about figure it out, but I don\\\'t have the nerve to try. They call it the Moebius splice with good reason http://www.precourt.ca/brummel_splice.pdf |
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Claus Riepe
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Following on from the last, have a look at this mind boggling way of doing an eye splice in dyneem when you can only get at one end of the rope. I think I can just about figure it out, but I don\\\\\\\\\\\\\\\'t have the nerve to try. They call it the Moebius splice with good reason http://www.precourt.ca/brummel_splice.pdfJulian, there is a trick.: You do not put in the hard eyes before you have prepared BOTH ends of the shroud. That way it is much easier to pull the second end through the strands of the first end. |
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