Fiberglass Studs and Bolts

Discussion in 'Fiberglass and Composite Boat Building' started by Southern Cross, Aug 19, 2013.

  1. Southern Cross
    Joined: Mar 2013
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    Location: So. CA

    Southern Cross Senior Member

  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I've seen epoxy fasteners, stables, brads and machine screws, but why bother if they're going to be bonded?
     
  3. Southern Cross
    Joined: Mar 2013
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    Southern Cross Senior Member

    Just thinking out loud..in lieu of hull/deck joints using stainless steel fasteners.

    Read about people stitching joints with rope (don't know what kind) and I thought fasteners made out of fiberglass or epoxy would make an excellent bond where as stainless never really bonds (which is probably a good thing in some cases).
     
  4. alan white
    Joined: Mar 2007
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    alan white Senior Member

    Mechanical fasteners like stainless bolts are incredibly strong when sized right. Nowadays there are also caulking gun style adhesives that are both very strong and flexible.
    I imagine that Spectra rope would be a strong way to connect some joints but it sounds kind of tedious and also difficult to fit neatly to say a hull/deck joint.
    Ideally, the hull/deck joint would be both bolted and bonded. It's easy to glass the inside but since it's hard to glass the outside without creating a lot of fairing and gelcoat work, the joint won't be as strong as it would be if you glassed both sides. Bolts help to make up for this weakness.
    Also, there's the question of whether you have access to the mating faces of the joint so caulk style adhesive is out if you don't have it between the parts. Hence both glassing inside and bolting is probably ideal in most cases where the boat is being repaired or upgraded.
    Regardless of claims of strength for plastic/glass bolts, flexing will reduce the ability of those bolts to meet their specs so it might be a good idea to use stainless on the hull/deck joint.
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I would think any line, including Spectra will just introduce some stretch to the situation, which is precisely what you don't want along the flange. The ideal setup is a solid laminate or a mechanical lock that can be undone for repairs. Introducing weaker and more flexible fasteners or bonding system is just self defeating, particularly in an area known for some weakness and flexing.
     
  6. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    The threads in a fiberglass bolt are really weak. Difficult to get good tightness in the joint.
    These are really intended for low stress situations where you need corrosion resistance.
     
  7. tunnels

    tunnels Previous Member

    why bother using fastenings ??

    A good deck and hull glued join is all that's needed ! the gluing surface need to be 60 mm wide at least and when they sit together get ooze out each side and smoothed off and that's all that's required !! . The proper adhesive is the key to it all !! . :D
    bolts nuts screws and all manor of fastenings are really not required at all !!:D
     
  8. Southern Cross
    Joined: Mar 2013
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    Southern Cross Senior Member

    For some reason I'm not getting the email notifications to updates on this thread.

    Thanks all for indulging my curiosity. I do try to research these things as much as possible but sometimes sifting through all the information becomes overwhelming.

    The amount of corrosion that takes place in our yard is incredible. I've never experienced anything like it before. Brand new anodized trailers start rusting within a few months. Algae and moss grows on decks left unattended and certain metal keels are rusting through the gelcoat. And stainless is rusting too. All of my bolts holding hardware began to rust badly, staining the deck. Tried everything, even separating stainless with glass or plastic cut washers. And the reaction of the dissimilar metals is something else, such as on the mast and the toe rail.

    It's all caused me to think of different solutions as I rebuild my boat.
     
  9. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Stainless to alluminium isloation is most effective when the joint is waterproof.

    This TefGel is the marine industry standard bedding coumpound. http://www.tefgel.com/contain.php?param=tefgel_infor

    The product TUFFGel is a anticorrosive locktight bedding compound used on mast or fasteners that need to be thread locked
     
  10. tunnels

    tunnels Previous Member

    you might be looking in the wrong place !!

    just maybe its the location you are in and has nothing to do this dissimilar anything its in the air !! air pollution is the problem !!
    In Rotorua nz the sulphur in the air use to really play havoc on older cars with chrome fittings, even the stainless ones go a funny colour !!.
    In the north shore in Auckland there a sewage pond and people have trouble with algae growing on the aluminium window and door frames at different times of the years !! its all airborne !!! :idea::eek:
     

  11. Southern Cross
    Joined: Mar 2013
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    Location: So. CA

    Southern Cross Senior Member

    That never occurred to me. There are oil rigs offshore and there are military bases next door.
     
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