Composite Chainplates. Vinylester Over Epoxy?

Discussion in 'Materials' started by Chotu, Mar 1, 2021.

  1. Chotu
    Joined: Mar 2018
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    Chotu Junior Member


    Sorry I was on a different project for a while and did not check back on the chainplate thread.

    Rumars has understood the problem perfectly.

    This is the answer I’m trying to find.

    Can I use vinylester in this case to laminate and secondary bond composite chain plates to the hull?

    Existing hull = glass(epoxy)/foam/glass(epoxy)

    Chainplates = many layers of uni carefully engineered and designed for construction and adhesion with epoxy. NOTE: chainplates are both inside AND outside the boat.

    Question: Can I use vinylester instead of epoxy?

    I’ll probably resin infuse these also.

  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Do it if you want to. But don't blame folk on here if the rig falls down.
    Sorry, I couldn't resist being flippant - but you are asking the question again on here, when you have quoted Rumar's answer to this question already where he states -
    "My answer is that it's a question for the vinylester resin manufacturer, or for a testing facility able to determine shear stress for the specific layup involved."

    Can you elaborate a bit on this please, re how they are arranged?
    Is there literally one on the inside (sticking up through the deck), and one on the outside, sandwiching the hull?
    If so, what is the hull thickness?
    Will the rigging toggle go through both chainplates?
    I would be worried about relying exclusively on a bonded joint for the outer chainplate, without any overlaminations (I presume that this is what you are intending?).
    If you have the inner chainplate overlaminated to the hull and deck, I would feel much happier.

    Edit - Chotu, you still have not told us how big is this catamaran that you are building.
    Bonding on chainplates to something like a 16' day sailer cat will be very different to bonding on chainplates to a 60' heavy cruising catamaran.
  3. Chotu
    Joined: Mar 2018
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    Chotu Junior Member

    Ugh. We’re not trying to re-design the chainplates here. Why can’t you understand this? I don’t want your opinion on what you think about composite chainplates. If you don’t like them and want to add bolts, you have no idea what you’re talking about so please just stop.

    So the answer you have to the actual question is, “I don’t know”. Got it.

    If anyone does know about substituting vinylester for epoxy in this lamination, could you please let me know what you think about it?

    I’m not posting a question to have people say “look it up.” I’m posting a question to see if anyone has actual experience substituting vinylester for epoxy in shear as a secondary bond.

  4. bajansailor
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    bajansailor Marine Surveyor

    Chotu, I have invariably found that it is always better to be polite and answer questions being asked by people who are trying to help you, even if you think that they are absolute dimwits who have no idea as to what they are talking about.
  5. Ad Hoc
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    Ad Hoc Naval Architect

    Well, one can conclude from the replies, no.
  6. ondarvr
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    ondarvr Senior Member

    I sell and instruct people on how to get a very good bond between these types of resins, but in this situation I wouldn't recommend it.

    You haven't provided any of the relevant information to provide a reasonable answer.

    Size of craft, intended use, size of the chain plates, calculated stresses, plus, and here's one of the problems, you need to know the exact epoxy and exact VE, and then hope someone has used, or tested that combination.

    You can use the different resins, but you'll need to increase the area of the bonding surface to account for the poorer physical properties of the VE. This may or may not be possible.

    There also other adhesives that could be investigated.

    Anytime I've done this, or walked someone through it, I Always recommend using the weaker material on the backside, then the bond is almost irrelevant.
    Last edited: Mar 13, 2021
    Ad Hoc, Rumars and bajansailor like this.
  7. bajansailor
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    bajansailor Marine Surveyor

    @Chotu I hope that you have not abandoned us - we are all very interested in your chainplates, and there is a large pool of talent on this forum who can give you good information.

    But as Ondarvr says :
    Even if you think the various questions posted above are ludicrous and a complete waste of time or not relevant, please bear with us and spend a few minutes to offer up some answers - the more information that you can supply about your boat, the better able the experts (not me) on here can advise you.
  8. rangebowdrie
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    rangebowdrie Senior Member

    I might be tempted to do, (just as an esoteric project,) what the "Wizard of Bristol", Nat Herreshoff used to do;
    Make a scale model of the chainplate and surface to bond against and test it to destruction,, but that's a lot of work.
    Probably just get some bolts and call it good.
    If weight is an overriding concern, (to the detriment of sound/safe engineering practice,) use Titanium bolts,, they can even be of tubular form.

  9. Milehog
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    Milehog Clever Quip

    Chotu , we like to know more about projects but you aren't sharing. Actually treating us like hired help except without paying wages.
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