Dux Diamonds

Discussion in 'Multihulls' started by catsketcher, Aug 4, 2015.

  1. tspeer
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    tspeer Senior Member

    It had to have been the Dux. The splices aren't long enough for the amount of stretch I experienced.

    I think what's happening is the weave of the entire shroud is tightening. It's probably not the material itself that is creeping. Once that initial process is over, they might be OK for diamonds. The trouble is, you won't know until you're in a high-wind situation, and then it'll be hard to back off on the loads if the mast is bending too much.
     
  2. groper
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    groper Senior Member

    We rigged our 40ft cat entirely with dux save the forestay due to the furler we had.
    So for our rig that was seagull striker brace, Inners, outers, and the caps. The rig design called for 8mm outer diamonds and we used 10mm dux so the windage is slightly higher but the weight much less. The caps were done in 13mm IIRC.

    I was also involved with changing the rigging on a 54ft mono sloop - triple spreader type, 23m mast. All the rigging was changed to dux including forestay, D1, D2, and D3s etc.

    On both rigs, on some of the splices you seem to get slippage, especially if you dont pre-tension them using a car towball or some big boat winches etc. I dont beleive it is creep, but thats how it behaves as you must keep retentioning them on the first few sails until you eventually run out of adjustment and have to shorten the rope by re splicing it. This was a big problem on the 54ft sloop, all of the diamonds had to be re spliced after the first weekend of sailing and going up the mast 3 times to retension all the diamonds. Only 2 of the splices on my cat had to be redone however -1 outer diamond and 1 cap shroud. The cat had alot more time to sit in the weather before loading it up with sailing forces however - a few weeks went by, whereas the mono we took out directly after re rigging it. So the splices need time to tighten up or they are prone to initial slippage - again i dont think the rope itself is stretching, i think its in the splice. If it was the rope itself, all of them would have needed doing not just some of them. None of them have had to be re-spliced a 3rd time. I think this is due to the very low friction fibers being very slippery and its difficult to get them to hold when the rope is new.

    Anti chafe braided sleeves are used on the spreader ends and wrapped around the lower caps for sheet ropes etc...

    The rig can be seen well in this video;

     
  3. HydroNick
    Joined: Apr 2010
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    Location: British Columbia

    HydroNick Nick S

    You might also want to talk to John Franta at Colligo Marine. As my first foray into dux I had cap shrouds built by him for my Farrier F-25c and they have been great. Since then I've done it myself with: a forestay; a bobstay with internal (in the bowsprit) cascading tensioner to allow me to telescope the bowsprit and "easily" (that's a relative term) tension the bobstay; and a load of other bits, including soft hanks; where required, fittings were from Colligo. I agree with the comment about softhanks (except I enjoyed sitting in the garden making them). I built the newer version called a Better Soft Shackle which indeed it is...but is still not as easy as a conventional hank to open and close, and this is particularly true if there is any tension, or flogging, when you want to open or close them; furthermore, if your eyesight or the light were failing they would be difficult to operate. They might be an "even better" soft shackle if they had a dayglo coloured tape tag sown onto the hanks at the location where they are pulled open (note to self I should do that on mine).

    Notwithstanding Tom's (far more informed than mine) comments on stretching of the overall piece, I believe that I am correct in saying that Colligo pre-stretches the splice, and there are heat shrink covers on the splice which appear to result in a splice that is probably not going to go too far on first use; of course, half the fun of dux is that you can make a lot of the rigging yourself, but for the diamonds application getting a pro to build them might solve some of the problems.

    One other point I will add a link to this discussion on the soft rigging thread that I started...so you will see a "new" posting...that won't be.
     
  4. HydroNick
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    HydroNick Nick S

  5. catsketcher
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    catsketcher Senior Member

    Thanks for the gear into everyone.

    I am intrigued with the issue of having to resplice the line. Could I not just terminate the ends further up the line and use a longer lashing instead of resplicing after use.

    I am pretty sure I can get enough tension in the diamonds with lashing. I did a test with some wire and got 50mm of prebend with a few grunts and a some 4mm lashed through the swaged ends. So can I just overspec the Dux, make the lashings 300mm long and pull them as needed?

    The wire did pretty well today in the test. Not a bad option if I can't work it out.

    This is a trailer boat and the rig will be up and down a lot. The diamonds will stay tight but the lowers,caps and forestay will spend most of their time looped up and stored below. Is Dux any good at this?

    cheers

    Phil
     
  6. groper
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    groper Senior Member

    Yep that's the go if using lashings. We used turnbuckles to the splice eyelet, so we had a maximum adjustment of around 100mm before running out of travel. Sounds like your good to go mate, it's very DIY friendly :)
     
  7. waynemarlow
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    waynemarlow Senior Member

    Try to use D12 or such like as your lashings as ordinary dyneema with a cover won't pull around a curve if you gave more than 3 turns through the eye as it seems to grip the other turns and prevents you pulling the line through with any sort of loading. D12 and the likes is quite naturally slippery and doesn't seem to mind being side loaded against other lines.

    The best method I found was to use standard wire eyes ( think really cheap ) of the type that are a constant loop and to create a mini cascade system, you can get 8:1 really easily without the line being passed a multiple of times through one eye.
     
  8. catsketcher
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    catsketcher Senior Member

    Gday Nick

    Do you mean the Antal ring type eyes or normal thimbles. The thimbles worked well on my test.

    I had a very interesting moment when doing the test. I placed the composite diamonds on the mast and held them in position with a G clamp whilst I sorted the rest of the rig out. I was gratified to see that a single clamp at the back was holding them on well so I undid the clamp with the diamonds wires tight and nothing happened. I could not move the things at all - a composite spreader band wrapped around the mast with wooden spreaders and nothing holding it on.

    Of course they were held on by the force of the wires. The wires however were not acting as beams pushing the diamonds back but as simple struts acting only in compression. Got half a diameter of pre bend with not too much tension.

    cheers

    Phil
     
  9. groper
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    groper Senior Member

    We just used normal stainless steel closed teardrop thimbles, not the type with a split at one end as they need to be as dimensionally stable as possible. The turnbuckle toggle just fits around the spliced thimble and the rigging screw went through the eyelet, pretty simple. This is the designed setup recommended by the local pro rigger and he was happy to sign off on it for insurance purposes, this is the way he professionally does all of his dux rigging when it's asked for.

    The colligo stuff looks neat as they have a dead eye type thimble which is all 1 peice and has 4 smaller holes machined through it at the right angles specifically for lashing. It's a little expensive tho. You might even be able to justify a small block set for the caps and or setup a canting rig ?! :D

    We didn't see any issues with the new rigging creeping until we had it out in some decent wind and loading it up with full sail forces, ie full unreefed sail plan in 20plus knots. Just holding the prebend in the mast etc is no problem and nothing moves... Same goes for light wind sailing...
     
  10. brian eiland
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    brian eiland Senior Member

    More Photos

    If you fellows wouldn't mind it would really help visualize some of this 'new rigging' if we could view some photos of what you are describing??
     
  11. groper
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    groper Senior Member

    Mine were done exactly like this - including the diamonds etc
    [​IMG]
     
  12. brian eiland
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    brian eiland Senior Member

    This posting in particular caught my attention as I have suggested wrapping some of the composite rigging 'around my mast tube' rather than conventional methods of attachment. So I would like to see a photo of what you are talking about,...if you have any??


    http://www.boatdesign.net/forums/multihulls/soft-rigging-solutions-47997-2.html#post735571


    http://www.boatdesign.net/forums/multihulls/soft-rigging-solutions-47997-2.html#post735744
     

    Attached Files:

  13. groper
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    groper Senior Member

    Brian, the modern way of attaching dux rigging to the top of a mast is to simply put another thimble on the mast- either bolted to a aluminium mast or glued / glassed on a carbon mast etc . In other words, pretty darn similar to what you've shown in you previous pic.

    This is standard practice on most modern racing rigs which utilise this type of fiber rigging...
     
  14. waynemarlow
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    waynemarlow Senior Member

    Yup standard tear drop thimbles do the job well.

    One thing though with this modern line is that it is relatively slippery in feel and you tend to use much smaller diameter than say wire as its quite a bit stronger. This brings some problems if you use it on some of the cleats, where under tension the line goes flat and being slippery the cleat can't grip it properly. I learnt to get around this by simply putting a short length of ordinary covered dyneema down the centre of the line at the point where the cleat has to work. The Dyneema holds the round shape and the line in the centre can increase overall diameter to the max of the cleat, it never fails.

    The other watch me is that sometimes you want an adjustible length so the standard non locking brummel splice with the tail simply out the side of the line gives that adjustibility. But beware, whilst under tension it won't slip and yet with very light jiggly type of loads, it will feed itself back through the splice. We tend to simply put a small knot in the tail which locks it off.

    Rather than totally wind line around the splice as per the photograph above ( unless that is for protection ? ) and you haven't used a locking Brummel splice, you can simply put a light stitch at the very top part of the bury in the line. Any movement at that point tightens the splice and it will never come apart. Don't put the stitch at the nearest point to the ferrel as that stitch will then take the tension.

    This type of line I am finding more and more uses and going back to lashings rather than turnbuckles has a lot of benefits and not just cost.
     

  15. catsketcher
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    catsketcher Senior Member

    Brian

    I am using T balls to told the stays on. The diamond spreaders are wood/glass. I will have a second set, misalignment with the first, ready in a few days and can take a photo.

    I have made a composite mast base and masthead too. Saved me quite a bit of money.

    Phil
     
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