Composite chainplates

Discussion in 'Fiberglass and Composite Boat Building' started by tbot, Sep 6, 2006.

  1. tbot
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    tbot Junior Member

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  2. DGreenwood
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    DGreenwood Senior Member

    There are many ways to make composite chainplates. The ones you are asking about are Dyneema or Spectra looped through a dogbone( a composite, aluminum or titanium pin) or knotted through a washer.
    Equiplite sells one that knots and is covered by a cup from underneath to exclude water.
    On Orange II they simply covered the knot with a light glass box bonded to the hull or cross beam. When it was time to change or check they simply cut it away and rebonded when done.
    Check some of this stuff out.


    Check out the whole Equiplight site. Tons of fun stuff.

    And some dogbones here ( called Easy shackles


    And if you like those look at these:
     
  3. DGreenwood
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    DGreenwood Senior Member

    Sorry...I screwed up the links....but I bet you know what to do.
     
  4. tbot
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    tbot Junior Member

  5. DGreenwood
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    DGreenwood Senior Member

    As to the security of the loops. If properly installed they are totally reliable. Any wear is obvious, you can replace them easily. The deck MUST be properly reinforced in the area to take the load. This is where carbon shines of course.
    I am not keen on the method used in the photo where the loop wraps over the shear. Seems unnecessary. Take a look at the knees in the photo on the equiplite site.
    If you have the download capacity I can send you some photos of some stuff I have done on an Open 60 and some videos of the way they are set up on ABN AMBRO. You may be able to get these videos off the net as well.
    If the proper reinforcement is in place, I feel it is such a superior method, that it is silly to consider chunks of stainless anymore.
    After work tonight I will see if I can dig up some photos.
     
  6. Figgy
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    Figgy Senior Member

    That would be super cool! Not to be a pain, but I would love to see them (videos) also. I've done a limited search on kevlar chainplates and havent found much, and even less on how to produce them. http://hem.bredband.net/b262106/Boat/chainplate.html
    The loops seem to be a much better alternative!
     
  7. tbot
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    tbot Junior Member

    Yes, in that way loop wraps over the shear but it seems that in this way blocks are placed as far out as possible. Most of the TP52's have them installed in that way.
    What's the other option? I'm sure that the systems on an Open60 and VOR took subject a way ahead.

    It's a small boat so there is actually no significant weight advantage but I'm going with mastbase loops for the Ti-Lites and composite chainplates for running backstay.
    When I've counting already grams for paint, I could loose a few grams with careful rigging.

    Now when I saw the dynex forestay attachment on Lutra V1 I'm keen to install similar system. :)
    When dynema loops are used with the conventional rigging (rod forestay in my case) what's with the elongation of dyneema in such combinaton?

    Thank you for the pictures in addvance!
    I have dsl - no problem for download.

    Figgy, I would not use the kevlar chainplates, especially when they are unprotected from the UV as on your pictures.
    I have very good results with carbon chainplates, if done properly they have super strength and offer a good weight savings.

    I'm just worried about making a big holes in the sandwich (in equipelite they use some wide diameter dyneema),that area should be adequately reinforced as DG. mentioned and that will add some weight, but in any case loops seems to be the lightest way...

    Another thought, is it better to use dyneema with cover for extra protection against chafe?

    Loops are very interesting subject...
     
  8. DGreenwood
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    DGreenwood Senior Member

    "Another thought, is it better to use dyneema with cover for extra protection against chafe?"

    I have seen them with an anti chafe cover and without. In the case of a dinghy or small boat where there is easy access I could see using spectra and leaving the cover off. Just keep an eye on it.

    "what's with the elongation of dyneema in such combinaton?"

    Less than the stainless if you eiminate "creep". When spectra is initially loaded you get what is called "creep" that is enlongation that is a result of the fibers settling into one another rather than stretching.Play with it a little and you will learn to account for that and adjust for it. When it stops creeping---IT STOPS.
    On the 60s some of them are using the loops on the jib sheets instead of tracks. (lighter) then they run a "twing" ( like a barber hauler) forward for adjustment. Way lighter.


    "What's the other option? I'm sure that the systems on an Open60 and VOR took subject a way ahead. "


    I'll try and send you some pics a video. And I will attempt to post them on this site....athough my kid thinks I'm the guy that can make anything work...I sure seem to struggle with these attached pics.

    I looked through my pics and I don't have anything as clear as this shot from the Equiplight site.These knees would be carbon and there is a poly cup that fits over the metal cup to stop water.

    And I love this shot of Groupama showing her tendons.

    And a repair I did on Ocean Planet . If you look down the deck you can see one of the loops sticking up (normally there is another alongside it that I have out.) At this point those loops have something more than 60K hard miles on them and they still looked fine. You can clearly see the carbon patch around the loop. That is around 3/8ths of an inch of carbon there, tapering out to a single layer.Those points on an open 60 have considerable load on them.
     

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  9. DGreenwood
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    DGreenwood Senior Member

    Take a look at these loops on Orange II Attached to forward face of cross beam.
    Really simple...really tough...easy to see and deal with problems.
     

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  10. DGreenwood
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    DGreenwood Senior Member

    Figgy and tbot

    I have been trying to send you the videos but the files are too large and my compression software won't seem to let me cut it into pieces. I will keep working on it though.
     
  11. Figgy
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    Figgy Senior Member

    Cool, if you can't do it, dont worry. Thank you for trying!!
     
  12. tbot
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    tbot Junior Member

    Those loops on OrangeII looks good,strong backplates with some sort of metal(looks like titinium) thru tubes.

    DG-at the equiplite systems, for example at the shrouds, how do they hold the loop in the lower SS cylindrical part? There is not enough space for the knot, maybe they clamp dyneema with something?

    Is there some source on the web for the videos?

    Cheers
     
  13. Jimbo1490
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    Jimbo1490 Senior Member

    Why don't both of you install the free version of Limewire and share the video over the (gnutella) network. Works for millions of snotty brats, why not you too?

    :D

    Jimbo
     
  14. joe blaney
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    joe blaney New Member


  15. CTMD
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    CTMD Naval Architect

    Joe, the designer of your boat should be able to "give" you a drawing for composite chain plates. Otherwise contact Gurit (SP systems) in Mona Vale and ask if they will design them for you. This isn't a place you want to be using rules of thumb.
     
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