Air voids in outer lamenent

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

  1. tazmann
    Joined: Aug 2005
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    tazmann Senior Member

    Hello All
    I am doing a gel coat blister repair job on my balboa 26'. Way to many to try to fix each one so I started stripping off gel coat to bare glass and grinding out any bad areas, looks like hundreds of air pockets in the outer layer of mat and the glass is solid on the outside of them. What would be the best repair, fixing what is exposed and sealing with epoxy resin or stripping off the outer layer of mat and rebuilding with fiberglass cloth and epoxy resin? Boats dry has not been stored in water for at least 3 years and so far only one small blister had the black liquid in it and that was just above the water line.
    Boats on the trailer and doing the work in sections bunks forward and bunks aft are stripped and the plan is to repair those sections then after cured sling it dropping the the keel out and do the center section.
    Couple pictures to see what I'm talking about and any input apreciated
    Thanks
    Tom
     

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  2. Herman
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    Herman Senior Member

    This first layer looks quite crappy. Probably never wet-out properly, or the resin disappeared due to bad cure rate and hydrolysis. (in which case it must have blistered badly, due to the uncured polyester falling back to where it came from, polyol and acids).

    Anyhow, I would strip it even back further (check on one spot if the rest of the laminate is better. If not, do not bother to remove this layer). Roll a relatively thin epoxy over it, and apply some glass fabric, or use vinylester and CSM. After that, finish with a bottom coat to your liking.
     
  3. tazmann
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    tazmann Senior Member

    Thanks Herman
    Good idea to check under outer layer first. it had hundreds of dime size and smaller blisters in the gel coat, no barrier coat just anti foul paint
     
  4. tazmann
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    tazmann Senior Member

    not much better

    Ground out a small section about an 1/8" deep and I can still see air pockets quite a bit deeper. Hull is only about 1/4 to 5/16 inch thick. looks like grinding out air pockets is not an option.
     

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  5. tazmann
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    tazmann Senior Member

    tunnels
    I think I agree, everything I have read on blister repair says the air pockets are usually only in the outer layer of mat not all the way through. this one may have been built on a Friday with the boss gone on vacation. Amazing it's still in one piece being 37 years old.
    Still feels solid when sailing and the rig stays tight so I think it is worth fixing
     

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  6. tunnels

    tunnels Previous Member

    I just deleted the first message i wrote ,so Start again
    You have the worse of the worst case of osmosis combined with bad workmanship ive seen . :eek:
    your boat seaworthy and safe again !!
    Its a major and you should treat it as such !. it needs to be ground back to get some of the crap chopped strand glass off a ways , then faired and filled to get the hull shaped and apply a couple of skins of good glass laid over the outside and used epoxy resin for the whole job and faired and painted !!
    Use epoxy all the way from start to finish that way you wont need to use any chopped strand matt any where as thats been the problem all the way!!,
    Lack of resin coupled with lack of knowledge plus bad workmanship and poor quality materials and you have the end results My choice of glass would be a triaxle obout 800gram run length wise against the hull (45/90/45) and the outside layer a 600 gram biaxle (0/90 ) and peel plied to give a good finish to work with . These glasses would be significantly stronger than what was there before and will add greatly to the overall strength of the hull again . :D:p

    Now i see the boat, would be best to take it off the trailer roll on its side and do one complate side at a time starting from just above waterline down to the keel line then roll it over and do the other side . the mast could be a way of holding it on its side .
     
  7. tunnels

    tunnels Previous Member

    Glass is amazing stuff and we learn new things every day !!
    Yes because of the voids in the inside layers i was going to suggest asking Herman about the possabilities of infusing the new outer glass layers to the old glass in hope the epoxy infusion resin being thinner could penetrate further into the older glass and help fill voids better .
    What do you think ??
     
  8. tazmann
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    tazmann Senior Member

    interesting idea, If they were cracked open I could see it helping but the resin and glass around them is still pretty solid. My epoxy resin has not showed up yet but it is supposed to be very thin non blushing so I figured try doing the first coat with a brush so I can work it into any voids that are open. I have only done pretty much basic repairs with epoxy and mostly with polyester resin but nothing this big so it's going to be a learning experience for me
     
  9. tunnels

    tunnels Previous Member

    Big jobs or small same things apply . Know the products you are using !!
    Make samples and use the resin on some glass and be very maticulous with weights and measures and percentages of resin to hardeners . mix the two together properly so it will all go hard !!! Also know the temprature and humidity as all these things will change the all important gel time . All work you do no matter what size is all govened by the time you have to work with the resin before it starts to harden !!!
    Remember deep containers and the epoxy will get warm then hot after its been mixed with the hardener so the warmer it gets the quicker it gels and throw hardens gelled containers it outside away from everything . in a big enough mass it could produce enough heat to melt plastic backets and to smoke and it stinks and could catch fire !!!.
    You have choices of getting slower hardener to give yourself more time to do what ever job it is . Changing the amount of hardener you use is a step into disaster and dont do it !! the slower hardener is a differant animal and dont mix faster and slow together or more potentual problems !! Do it by the book and all will be well . very quickly you will get the hang of it all !! it just takes a little thinking about and understanding !! keep the lids on containers that you finshed using Its exspensive and you dont want to loss any for any reason !!!:p
     
  10. Herman
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    Herman Senior Member

    Infusing a laminate onto it would be a good solution. It will fill more voids than doing it by hand. However, I would understand any reluctance doing so, as you need some skill (people on the forum could help, including me) and you need some relatively specific materials in small quantities. Best thing would be to "borrow" this from a neighbouring company that does infusion, or perhaps there is a company that sells small packs?
    There are some materials nowadays that make infusion relatively idiot proof.

    But I can fully imagine that the step from making small parts to infusion of a sponge-like boat can be a bit too much. In that case, take your ordered resin, and build up a small patch to see if you can improve the laminate. (I suggest taking the area which you ground off, as it needs buildup anyhow.)

    In that case follow the advise of Wayne, with the addition to source materials that are available locally. Again, you need small quantities, so pulling them from a roll at a company working with these materials would be your best bet. Otherwise you will need to order a roll, and in that case I would order a roll of 16 oz (600 gr/m2) biaxial, which leaves a relatively smooth surface, is easy to work with, and you save yourself from buying another roll, which would add to the cost. The absense of a bucn of fiber in 0 direction is nothing dramatic. It will not get any worse than this anyhow.

    And indeed this is one of the worst cases of osmosis and hydrolysis I have seen. I am sorry to say that.
     
  11. tunnels

    tunnels Previous Member

    And indeed this is one of the worst cases of osmosis and hydrolysis I have seen. I am sorry to say that. I to agree but it is still solid and sailable and if you make a good job you wont have any problems again . I hope you dont mind i scimmed the pictures to add to my collection of glassing things !!

    I used to make fibreglass spa pools for a company long long ago and they would get osmosis in about 3 hours it began to show with all the hot water and chemicals that were in the water so haul it out and sand and epoxy coat tha same colour , sell as a factory second !!.Was glad when they switched to acrylic shells backed with frp !!!

    The things we did !!!! :D
     
  12. Herman
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    Herman Senior Member

    Swimming pools and the like call for special chemical resistant gelcoats. For sanitary ware heat shock is also an issue. Keep close with your gelcoat supplier, they usually have a range of products that fit. (and that is not always what is available in the factory making the tubs)

    As for the boat: A bit of labour and it is as good as any other boat, might even be better.
     
  13. tazmann
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    tazmann Senior Member

    Many thanks for your input
    Few things working against me , lacking skill and help, glassing over head, and glassing outside in dirt driveway. One idea I have, rather than trying to do a big section over head short handed would be to do it in one foot wide strips with about a 6 to 8 ounce cloth, starting from waterline down to center line then skip 10" and do the next then after the fist strips cure feather the edges back an inch and glass in the interconnecting strips.
    My experience glassing overhead is a bugger and slow going compared to down flat
     
  14. Herman
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    Herman Senior Member

    Glassing upsidedown sucks. When you are alone indeed take small strips. Butt join them, and do 2 layers with staggered joints. That should do it.
     

  15. tunnels

    tunnels Previous Member

    Upside down glassing is a test of ones skill and how well you can adapt and make a system and go for it . Getting prepared is the key like all things , measure the length and make the strips about 400mm wide ,roll the glass so the loose end is the one at the keel where you will start . leave about 200 mm hanging out , get under the hull and have your resin in a paint tray !!, i would use a short haired 6 inch wide mohair roller . Roll a coat of resin over the whole area first so the glass will have something to cling to and then use you hand and place the loose end of you glass on the wet area at the keel and smooth it out and then start with you roller and wet gently !!,staring to unroll the glass and use the mohair and roll down at the same time i always work across the glass making sure the mohair is wet but not dripping!! gently slide yourself backwards and unroll your glass at the same time !!
    Take you time and dont be tempted to try and unroll to much glass ahead of yourself if it drapes it will fall and pull all the glass with it and you will have to start again !!! !trying to hang wet glass is almost impossible by yourself . apapt your system to suit yourself I use the resin roller in my right hand so the resin tray i keep on my right side and place a sheet of ply or something to sit on so you have everything at your finger tips scissors ,and gloves and roller etc etc !! make sure all the way from your starting point that there are no loose ends or strands of glass hanging down , glass needs to have enough resin to stick and stay only . dont be tempted to apply to much resin you can do that later when you do the next strips . dont be tempted also to run the roller over the area where you first started as it tacks on the surface and will cling to the roller and end up tearing the lot off or wrapping it around the roller
    Like Herman said butt the joins and you can gently move the wet glass with you paint roller by rolling and siding the roller side ways !!.
    As time goes by you will get used to it and itand becomes a piece of cake . let the first layers harden !!
    The second layer cover the joins of the layer below by at lease 100 mm or even more and do the same butt the joins , Epoxy had lots of guts so small gaps where glass dosent join will simply get filled later .
    Good luck and enjoy !!:D:p:)

    You would be amazed at the amount of professional glassing people that cant hang glass on a surface over hanging like to side of a hull in a mould even !!,we used to use a broom and rolled the glass onto paper tubs once you get you system its really easy and quick .
    Using a chopper gun and spraying glass on a over vertical surface is just as tricky but works if you know what you are doing . First time is a laugh!
    all the glass hangs there for a few seconds then rolls off into the bottom , trick is to get close and use the force of the resin to blow the glass against the mould !,start at the bottom and work across from side to side and upwards .
    Used the same system when spraying polyurethane foam from a gun also ,start at the bottom and side to side and working up
    wards , the liquid foam goes on the suface and the warmth from the spray before activates it and woosh it really exspands in a hurry .
    Ah the things we did !! .
     
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