What type of fiberglass (roven/stiched/mat) for infusion

Discussion in 'Fiberglass and Composite Boat Building' started by GringoJohn, May 8, 2012.

  1. GringoJohn
    Joined: Nov 2010
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    Location: Quepos Costa Rica

    GringoJohn Fish Slayer

    Awesome, great advice, stitched it is. Anybody know where a good place to get low vis vinylester is? Should I inject the VE resin as it comes, or try to dilute it with a little styrene? would like to start off with a 5 gallon, but if I did a boat, buying by the 55 gallons would probably be better. I was looking at US composites, but they don't do 55 gallon drums. On the 38 footer, how much resin are you using per boat? I know there are formulas based on weight, but the real world guys sometimes vary so I thought I'd ask???

    I will read more, and have read lots of the infusion articles on here. There are very few other places where you can get good info, just this forum dedicated to crazy people who think it's fun to build their own boat...Hopefully i'll be one of them soon...

    I bought a JB industries pump. I went on a HVAC website / forum, and that pump won one of the polls so I figured it must be the best. It was a close toss up with a different brand, i don't remember which, and I had heard alot about the other brand, but there were lots of people that voted, and since they are the experts in vacuum pumps...
     
  2. groper
    Joined: Jun 2011
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    groper Senior Member

    any decent composites supplier will be able to supply you with an INFUSION VINYLESTER... dont mess with it, it has already been designed for infusion...

    Nobody can tell you how much resin YOU will use... you have to calculate it from your laminate stack and consumables... with a perfect vacuum, you will get approx 65-35% fibre to resin content in the stitched reinforcements, but they are all different so you need to do your own testing with the exact type/weight/brand of reinforcements your going to use in order to calculate it accurately.

    It seems your doing powerboats... so minimum hull thickness is important, you will most likely need to include a vacuum compression resistant bulking matt like soric in the laminate to increase the laminate thickness on the bottom skin in conjunction with your reinforcement and foam core then inside laminate etc...
     
  3. GringoJohn
    Joined: Nov 2010
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    Location: Quepos Costa Rica

    GringoJohn Fish Slayer

    Ok, what would say say a minimum hull thickness outside of the corecell would be. The boat will be diesel powered and won't go over 25 knots. I looked at the soric, that's what I was thinking for the infusion medium.
     
  4. groper
    Joined: Jun 2011
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    groper Senior Member

    I am not familiar with powerboat design and so cannot answer, neither can anybody else without knowing the entire boat design...

    I would make an ASSUMPTION that your total outside skin laminate would be at least 6mm on the bottom of the hull surface to protect it from impact with floating debris and wave slamming etc... the topsides should not need any extra thickness beyond the reinforcements as it is a cored sandwich laminate.

    So i would ASSUME/GUESS you would use something like a 3mm soric with your other triax reinforcements on the bottom of the hull, then just some triax only on the outer topsides (and inside) of the corecell....
     
  5. groper
    Joined: Jun 2011
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    groper Senior Member

    Infusing this in 1 shot will probably cause some exotherm issues due to the laminate thickness... something else to think about and plan for...
     
  6. GringoJohn
    Joined: Nov 2010
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    Location: Quepos Costa Rica

    GringoJohn Fish Slayer

    Would it be a better idea to do it in two parts. Maybe the outerskin with peel ply, and then the second phase with the soric, foam, and inside shell?

    My dream boat is a 31 gamefisherman. Here is a picture
    [​IMG]

    This boat in 1 inch corecell cored vinylester and I can die happy... Would 1 inch work, or should I go thinner??? The idea is a hull that provides insulation so the fish can't hear the motor.
     
  7. CatBuilder

    CatBuilder Previous Member

    Nothing wrong with 1". That's what my hulls are made from.
     
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  8. tunnels

    tunnels Previous Member

    matt, woven ,stitched ????

    Keeping life simple is always best ,some general rule of thumb and peace of mind knowing its going to work !
    The resin you use is in a lot of cases the limiting factor of what you should and can use be it hand laminating or infusion . Matt (choppedstrand ) is a fill in , in between layers of either woven or stitched materials . The weight of the matt is always low as its just used as a tie layer to glass reinforce the resin layer between the other materials . 275 gram to 300 gram is about the norm that will come as part of what ever you choose . If hand laminating then this chopped strand layer can be used to speed up the laminating process as it holds a good quantity of resin so the next layer on top will wet out much quicker hence the term labour saver used in glass manufactures , wet on wet layers and rolled out properly save resin as the fibres are able to be compressed and theres less float apart takes place Its quite amazing the amount of resin that can be saves doing this .
    Polyester resin is best suited to chopped strand matt usually 450 gram or even 600 gram ! 600 gram is hardly ever seen these days , Woven is also best suited to poly resins as it wets quickly and the woven soaks and uses quite a lot of resin . BUT the woven is a easy to use quick to lay and makes a strong robust laminate specially for commercial fishing boats and the like .
    To get one step further ,The use of vinylester resin is a big step forward and differant materials can be used because of its superior qualities and strength .
    This is where you can think Stitched materials ! non woven . 275 gram chopped strand attached to the better glass and because it non woven lays flatter makes a thinner layer and untimately uses less resin . Better quality glass means you can use less glass and again a weight saving !!. While you are getting your head around all this you have to completely understand the purpose of the product you are making and what it will be used for and how will it be used . Product knowledge is very ,very important and there are not to many people that take this into consideration when racing off to make what ever its is and after its finished and been in use find its falling apart and not doing what you thought it was going to do or it gets damaged and literally tears apart because of what you have used and how you used it . Materials have changed over the years and so have thoughts on how and what to use . we exspect to get more by using less and cant understand why we cant and keep getting it wrong !!.
    You can come up with a magic light weight lay up that is just what you have always wanted BUT what resin system are you going to use to hold all those beautiful materials together . Everything has it uses and everything can be used with everything else but its understanding what should be used with what thats will be the key to your success . To use less the materials have to be better !,to be better the cost goes up and there is not limit as to where to stop! Infussion is the magic catch word and people have this feeling if its infussed it must be the best !! well its not !!
    Any job is only as good as the people that lay the materials and tieing everything together with laps and oriantation of the fabrics that are being used, this is what makes or breaks any job . Product knowledge is something that take years to learn , oh yes you can have a degree in compostite engineering but do you really undertsand intermitly every material thats in the arsenal for you to use , do you fully understand the oriantation of the glass strands used to make all the fabrics and how they will behave ?? How well do you understand every part of a boat hull and everything it will have to endure in everyday use . You can read books till you fall aleep every night and sit for hours in front of your computer for days running into weeks and print off screeds of information but unless you have had your hands in gloves and worn a mask for hours you donot and will never fully understand what the material you are playing with will do and what it is capable of .A very high percentage of the most valuable information available is carried in peoples heads and not written anywhere .:D everything works !! but how well ??
     
  9. groper
    Joined: Jun 2011
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    groper Senior Member

    1 inch corecell would typically be fine for that size boat and probably overkill, but the frame and stringer separation is what really determines the core thickness you need...

    If you want someone to give you a full laminate schedule, nobody will because its part of the entire design process... nobody knows the design thats in your head besides you. You can reverse engineer another similar boat if you want, to give you an idea of the laminate schedule you might use - but if you want to use infusion, then the boat you reverse engineer should also be a well engineered and infused boat otherwise you wont get a fair idea.

    yes to avoid the exotherm causing cosmetic problems, i beleive most people hand laminate a skin coat over the gelcoat to stop and print thru etc...

    Id do alot more reading to avoid asking basic questions, look at other builds people are doing on the web, theres heaps out there but it can take some searching to find them...
     
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  10. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    OK, back to basics.

    You want to infuse a 4x8 ft panel, to see if it is feasable to do an entire hull. You lack a reliable and skilled laminating crew, so hand laminating a boat is less than desirable.

    -resin
    You want a VE resin (good choice, strong but still cheap, and normal ISO-NPG gelcoat can be used for your boat hull). get an infusion resin. This is a non-thixotropic resin (no additives like glycol or aerosil added). Thinning a hand laminating resin is not a good idea.
    Most infusion resins come unpromoted. There are basicly 3 chemicals you will probably add:
    -peroxide (in the USA referred to as "catalyst"). Consult your supplier, as you want a slow curing, low H2O2, low exotherm catalyst. H2O2 will cause foaming of the mixture.
    -cobalt solution. This is the true catalyser. Make sure you know the concentration of the mixture (1%, 6%, 10%) and also double check the concentration used un the datasheets. Correct and adjust if neccesary.
    -acetyl aceton. This is a retarder for vinylesters, which will give you more time to infuse. Depending on the catalyst used, you will not need it, but if you are ordering materials, and you have the chance to order a quart or so of this material, do it. If you use it, you will probably need 0,03-0,1%, so a quart is enough to have at hand.

    Do your own tests, to get a feel for the resin, the geltimes and the final cure. Base your tests on the datasheets. Depending on the project, aim for a 1 hour geltime (4x8 sheet) or a 2 hour geltime (boat). Make a series of 100 gram pots in which you add different amounts of additives.
    To add 0,03% of an additive into a 100 gram cup seems impossible, but with an accurate scale it is possible: add 1 gram of the additive into 100 grams of resin, and mix. Add 3% of this mixture into another 100 gram cup of resin, and the final effect is that you have added 0,03% of additive into that resin. Simple and useful trick.

    Reinforcements.
    There are a lot of reinforcements that can be used. Multiaxials in general are relatively easy to infuse. also aramides can be infused succesfully. (I prefer using aramides in a 50/50 mixture with glass, in a woven style or a multiaxial).
    Wovens can be used succesfully as well.
    CSM is more difficult. Thin layers of CSM every now and then work, but their permeability is very low, so they need back up by a more permeable material, or infusion mesh. They can be useful against the gelcoat, to prevent print of the more course materials in the laminate, or between multiaxials or wovens to improve inter laminair shear strength. For multiaxial 150 gr/m2 is enough, for wovens 225 or 300 gr/m2 will do.
    If more permeability is desirable, or thickness is wanted, a unifilo can be used, but I would steer clear of this in cored boat construction, unless for specific reasons.

    Cores.
    any core can be used, but they need either cuts to conform to contoured shapes, and/or perforations, to allow the bottom laminate to infuse properly as well. Scored foam should be "knife cut" and not "saw cut" as the larger channels of the saw cut versions will allow "race tracking" of the resin around the blocks of foam, causing dry spots in the middle of the blocks. (seen many times)
    Perforation can be every inch or so, a 1/8" drill hole is already on the large side. 3/32" is already enough. Core-Cell "double cut" style does not need perforations, and is easy to use.

    Infusion consumables.
    Bag: get a good quality bag. Agricultural plastic won't do.
    Sealant tape: idem
    Mesh: some use shade cloth, no experience with that. Over here shade cloth is costly, and infusion mesh is cheap, and conformable to contoured shapes.
    Runner material: plastic spiral will do
    Perf film: this will allow you to get the mesh off the laminate. Get a very open one, P-perforation style, or P16, MP22, of P1. Do not use P3, which is offered many times.
    Peelply: this is only optional. Leaves a course surface for secondary bonding.

    Infusion strategy:
    There are more strategies possible, therefore it is advisable to understand the infusion basics. To be short a 4x8 sheet I would feed on both long sides, and vacuum in the middle.
    A boat I would feed on the keel, and do a fishbone upwards. Vacuum on the sheerline. Chined boats can be done similarly, but different in details.

    Labour:
    In my experience, sloppy laminators are equally useless when it comes to resin infusion. Someone doing a resin infusion job does not need to know anything on hand laminating, in many ways it is even a disadvantage (this might explain the dislike of Tunnels to resin infusion). What you need is accurate workers, perhaps taylors. Women are usually better in this than men. What is important is accurate placement of fabrics, little or no overlaps, well pushed into corners. Accurate core placement, no gaps between the sheets, which cause racetracking. accurate consumable placement, only small overlaps of the perf film, the runners in the right place, etc.

    Vacuum drop test.
    Pull a vacuum. Close the bag, and use a vacuum cleaner to get most air out of the bag. (just stick in the hose of the vacuum cleaner in the last open bit of the bag, the hold with your hands. This is more than enough. Once the bag is down on the laminate mostly, close the remainder of the bag, and pull a light vacuum with your pump. Keep in mind that a refrigerator-vacuuming unit does not like running at less than perfect vacuum, and will spit oil if you do. You will notice.
    At a light vacuum, re-consolidate the inner corners, then pull a high vacuum.
    Once you are satisfied with the vacuum, chase leaks, and do a vacuum drop test. Isolate the part, and see how much the vacuum drops in 15 minutes. It should be no more than 5%, preferably less.

    Once everything is OK, mix your resin, and infuse.

    One thing i forgot is to setup a test first. Do a 1ft wide strip of what you are planning. This will help determining the needed geltime for your large project.
    As a resin infusion consultant I have ****** up plenty of 1ft wide tests, but never a large part.
     
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  11. packsail
    Joined: Feb 2012
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    packsail Junior Member

    I tried a 120 gallon air compressor tank as an accumulator. The only thing that it accomplished was sucking oil out of the vacuum pump. Make sure if you use an accumulator that your vacuum pump has a check valve in it. I've found that a 2.5 gallon resin trap suffices as an accumulator.
     

  12. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    Something I forgot: accumulators (large tanks) are only useful when your vacuum pump has an automatic switch, so switches off once a preset vacuum has been reached.

    This has the advantage of reduced noise, power consumption, and it gives you some audible alarm: when the pump keeps its mouth shut, everything is still OK.

    A large vessel reduces the amount of switching. Another advantage is that at applying a vacuum, you have a "vacuum reserve" which helps to draw the bag down.
     
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