Air voids in outer lamenent

Discussion in 'Fiberglass and Composite Boat Building' started by tazmann, Jul 18, 2012.

  1. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Salt water actually moves slower through a substance than soft fresh water, this is why lakes frequently have higher incidences of blistering than salt water, and the warmer the water typically the faster it will blister.

    Even the best gel coats are a temporary barrier to water, and after many years water will find its way through. Since this is a very old hull that sat in the water long term the gel coat wouldn't have made a difference. Short term yes, long term no. And like in most blisterd hulls the blisters are located in the laminate rather than the gel coat.

    We do extensive blister testing with many different combinations of resin, glass, barrier coats and gel coat, and yes, there can be a big difference in the results depending on the combination of products used. Change any one of the variables and you can go from great results to poor. Add in operator error or ignorance and the hull doesn’t have a chance.
     
  2. tunnels

    tunnels Previous Member

    Hello
    All you have written is very interesting material !! would you be able to elabirate further to what you have written ??
    I know that many others plus myself would be greatly interested i the combinations and variables of building to slow or stop the intrussion of water into the hulls .
    I love Delving into the microscopics of things and it can give a greater understanding of the eventual mechanics of how resins penetrate the bundles with papilary action to incapsulation fibers and how breaking up the bundles and seperating the fibres will eventually give better strength and durability .
    Scimping and starving layers of resin to me is and never has been a good thing to do . i have always advocated that there is a fine line between what is the optimum resin content ,and what is to much and what is not enough !!!. I can see merits in Resin infussion but i have never been a strong believer if the amounts of resin not used . i donot believe resin infusion is the be all to end all hat we are lead to believe theres lots people are not told and will learn in time !!
    Am i right ???:p
     
  3. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    For infusion you need to take extra measures to prevent blistering, the likelihood of blistering goes up as the resin content goes down, there is also an issue with cosmetics, they tend to get worse for the same reason.

    For best blister resistance you should use a good marine gel coat, a VE barrier coat and a resin rich skin of a good VE that is formulated to be used as a skin resin. For infusion you should add a layer of fabric that will create a resin rich layer next to the barrier coat. This will help with blistering and cosmetics. If you skin the hull prior to infusion then this fabric may not be needed.

    You can't stop the water from being absorbed, you can slow it down and use materials that aren't as affected though. VE can actually absorb water faster than lower grade resins, but won't absorb as much, and doesn't break down at the same rate, so it is less likely to blister. The bond to itself and the fibers is better too.

    This all assumes the materials are used correctly, do something wrong and you’re on your own.
     
  4. tunnels

    tunnels Previous Member

    ondarvr

    Your posts are filled with lots of things that are making me smile and things that i have though were true but have never had answers when i asked . its like you have to sign a pledge when you join the infusion club that you never tell anyone anything !! there is good and only good to be had from using it !!. I almost see red when i see people wanting ways of saving weight and the first place is always the hull !! that one place that in actuall place should be about third place on the list of places to get rid of kilograms from those obese boats .:confused:
     
  5. tazmann
    Joined: Aug 2005
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    Location: California

    tazmann Senior Member

    Yep something was defiantly not done right, resin/hardener perhaps.
    Did a lot of grinding the other day and rinsed it with water a few times sense. in the areas that I have ground down to the first layer of woven I am getting some nasty looking dark stuff coming out in spots here and there. Went out this morning to pull out a couple through hulls and get the keel ready to drop out. Did a close inspection of where I had ground now that I am not tired and covered with fiberglass dust and found a number of blister spots quarter to half dollar size up deeper in the laminate and a Few I believe go all the way through some still have a solid layer covering them like if the damage was from the inside. Not good for sure.
    Could these be ground out, treated as holes and built back or would I be like feeding a dead horse ?

    Polyester mites had a picnic with this one!!!!!!
     
    Last edited: Aug 12, 2012
  6. tunnels

    tunnels Previous Member

    what ever you find and what ever you repair is all ways better than it was so its always improvements .
    do what you feel has to be done and the end result will be 1000 times better than you had before . :p:D:p;)
     
  7. tazmann
    Joined: Aug 2005
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    Location: California

    tazmann Senior Member

    OK anything that looks real bad or has a dull sound when I tap on it I'll just grind out till gone and repair accordingly.
     
  8. tunnels

    tunnels Previous Member

    Its sound cool ! its a oncer and will never have to be done again !!:)
     
  9. tazmann
    Joined: Aug 2005
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    tazmann Senior Member

    Hope so
    Nothing sucks more than having to do the job twice.
    At least there are not that many larger deeper blisters.
    Doing some rough figures on whats removed and cost-weight per layer to replace. I need to add back about 3/16" to get it to about the same thickness as original counting the gel coat
    That would be close to 3 layers 17 ounce biax without mat ?
     
  10. tazmann
    Joined: Aug 2005
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    Location: California

    tazmann Senior Member

    Could be that magnified the problem, open gel coat blisters and being slipped in a fresh water lake that gets low and warm by the end of summers.

    So far It's going good, what I have stripped looks a heck of a lot better than what was there, I don't feel like I would be just glassing over crap although it sure would have been easier just to cover it up with a couple layers of cloth and hope for the best.
    My Biaxial might show up today and that would be nice so I can do a couple test samples to see how thick and stiff it is.
    I still have quite a bit to strip and get ready before I even think about applying the glass

    I thought about maybe buying a few yards of 5 ounce Kevlar cloth or 9 ounce biaxial Kevlar and putting a layer on the bow down to around the keel pivot point to help with abrasion and give a little better strength/stiffness but after reading up on the subject online I am more confused now than before I started. Anyone have any real life experience lining with Kevlar? Heck a few yards of the 5 ounce were only talking 50/60 bucks, the biaxial is pretty pricey though.
    Tom
     
  11. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    I think xynole is better for abrasion than kevlar--see if you can find it in 8" or 12" tape.
     
  12. tazmann
    Joined: Aug 2005
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    Location: California

    tazmann Senior Member

    Found it in wider rolls certainly cheaper than Kevlar. Is it about the same as dynel ?

    Biaxial showed up, It mikes out at about .027" dry, looks like it's gona be fun overhead !
     
  13. tazmann
    Joined: Aug 2005
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    tazmann Senior Member

    I didn't get any grinding done this weekend, worked Saturday and then just worked on getting keel out Sunday, turned out being quite a project in itself, pivot bolt and nut came out easy but the pipe sleeve was rusted dang near solid in the iron keel, Finally gave up and got some long saws all blades and just cut the sucker from under along both sides of keel, should have done that to start with
     
  14. SamSam
    Joined: Feb 2005
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    Location: Coastal Georgia

    SamSam Senior Member

    Kevlar has strength properties, stiffness isn't one, but flexibility is. It will stretch more than most laminate materials before breaking. Carbon fiber is the opposite.

    Kevlar also fuzzes up when abraded.
     

  15. tazmann
    Joined: Aug 2005
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    tazmann Senior Member

    kevlar

    I have been reading up everything I can find on the subject and have came to the conclusion to forget any of the high end stuff, just go with a good solid layup with the biaxial and spend the money on positive flotation
     
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