Refinishing Hull

Discussion in 'Fiberglass and Composite Boat Building' started by RufNutt, Jan 8, 2013.

  1. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Since you've removed the gel coat, you going to have to seal up that laminate and if using epoxy, you'll need at least 3 coats of epoxy (not paint), before top coating with whatever.

    Of course now you have to fair the whole hull, which is a lot more work then just fixing spots. Then the surface will need to be smoothed, then sealed with a minimum of 10 mils of epoxy, then prepped for paint. Interlux vcm performance is just a paint and will not seal the laminate.
     
  2. RufNutt
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    RufNutt Junior Member

    Ya I realize it is alot more work , but I will know what I got in the end. Myself I don't like to cut corners and this is the proper way to fix a blister problem after reading alot of guides. Talking to Interlux today they said I could use the ip 2000e with the vcm performance as a top coat for under the waterline. Also they said I could go without the IP if I didn't want to do a barrier coat and just put the vcm on We are into a hard winter here, it was -31 here today so i don't think I will be doing any boating soon.

    Also like I said after attacking the blisters on the bottom of the hull myself I had over 1/3 of the laminate off picking at the blisters. So I ended up with that and then probably 50 spots to fix up to 3 -4 inches in diameter. So I also thought what is the laminate actually like where I am not picking....can't be good. I figure strip it down then sand the hull with some good course sandpaper then start the epoxy from there.

    Someone on here must have done this before do you have any pointers of not what to do

    Thanks
     
    Last edited: Jan 18, 2013
  3. PAR
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    PAR Yacht Designer/Builder

    Several of us have stripped hulls like this. Make sure you use enough base coats of epoxy, to insure a true barrier. The laminate of that boat isn't waterproof without it's gel coat and paint alone will not seal it, in spite of what some salesman from a paint company told you. The minimum thickness for a sufficient barrier, under the fairing compound, is 10 mils. This means 3 uniform coats of straight epoxy. You can do your fairing before or after sealing the hull with an epoxy barrier. Good arguments can be made for both methods, but I usually do the barrier last and fair the hull first, so my filler bonds are against the hull shell. I do this because, if the barrier coats go down first, you'll sand into them as you fair the hull and decrease the film thickness in spots, some of which will not get over coated later. Rather than run this risk, I barrier last, so I can insure the coats on top, are as thick as they need to be. This technique also tends to lock down and seal the fairing compounds too. I do smoothing operations with high build primer and again several coats, to insure sufficient film thickness under the top coats.
     
  4. RufNutt
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    RufNutt Junior Member

    Very good info Par and I really appreciate it as experience always beats what is on the can.

    If we lived by what we read on products there is some miracle stuff out there.

    Sounds like this IP2000e is one of them products. Suppose to do everything.

    Even if I use the ip2000e i still need to use a sealer of straight epoxy first.


    So why would I go and put ip2000e on over top of the 3 layers of epoxy, is that a waist of product to even use the IP .

    Now again I found a few stress cracks in the bow of her so I presume they were caused by the weak stringers I had replaced before I flipped her as the stress cracks followed the stringers. The factory stringers were not installed good at all. I looked after that and we did them right.

    So saying that do I have a flex problem with this 18 ft hull and need some product with flexible abilities, and again IP 2000e is suppose to cover this problem or did i fix that with the stringer replace.

    Do you use high build primer below the water line and if so what brand as one of the guys brought that up yesterday?

    Thanks
     
  5. dzausta
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    dzausta Junior Member

    wouldn't it be a good idea to just use gel coat? gelcoat is still used to resurface hulls.

    possibly drop a layer of csm on top of your ground out area and just gelcoat it.
     
  6. RufNutt
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    RufNutt Junior Member

    dzausta yes gelcoat is used to resurface hulls. But there are alot better products out there today to help with blister problems then what was used when the boat was manufactured. Also gelcoat was never really meant to be sprayed other then on a mold.

    So really if you start spraying gelcoat and thinning it etc you are actually compromising the gelcoat form the start. I hate the stuff as it is. I actually worked with it years ago but never did repairs, that was the other department. I was never actually happy with any repairs I seen 2-3 years down the road if it wasn't waxed and buffed before you looked at it. Now complete spray would age the same and yellow the same so you would not notice it as bad, but I know I would. So I guess it is a matter of preference and I would like to try a new product...LOL maybe in the end I will not like it either .
     
  7. ondarvr
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    ondarvr Senior Member

    The blister is issue is from water permeating the laminate through the gel coat, this is what creates the problem. Just fixing the blisters and applying gel coat would result in the hull blistering again.

    Epoxy is more water resistant and less permeable, so the laminate will stay dry much longer and will be far less likely to blister again. This all need to be done correctly for it to succeed though, take short cuts and failure is common.
     
  8. PAR
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    PAR Yacht Designer/Builder

    I've fixed plenty of botched up blister repairs, because they tried gel coat again.
     
  9. dzausta
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    dzausta Junior Member

    so they normally come back if not epoxied? what would happen if you just ground it all out and re-laminate some glass than gelcoat? just curious
     
  10. PAR
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    PAR Yacht Designer/Builder

    Blisters develop as a result of the interaction of water and the the chemicals used in some polyesters. If the laminate is prone to blister, then it has one of these polyesters and it will always be a problem. The only true cure is to remove the gel coat (yep the whole darn boat) and barrier coat, typically with epoxy. This seals the surface and prevents water from interacting, with the screwed up chemistry in the polyester laminate. If you apply gel coat, even over some mat (why), you'll still have the same problem - a less than waterproof coating over a vulnerable laminate.
     
  11. dzausta
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    dzausta Junior Member

    "A less than waterproof coating" can u explain that? I thought gelcoat is waterproof?
     
  12. ondarvr
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    ondarvr Senior Member

    Nothing is waterproof, there are only varying degrees of water resistance, and epoxy is a good deal more water resistant than gel coat.

    Over a period of time water will migrate through the gel coat and into the laminate, sometimes this water causes problems and sometimes it doesn't. When it does create problems and is then fixed, the laminate is still susceptible to blistering again if water continues to migrate in to the previously unaffected laminate. The unaffected laminate would be what is under the previously blistered layers that had been removed.

    You could re-glass the hull with polyester and then gel coat it, but why go through all that work and risk possible failure.
     
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  13. dzausta
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    dzausta Junior Member

    Oh ok I've been reading some posts where ppl have been saying water can't get through GC and is just as good as epoxy for water protection. Point taken, thx for the clarification. I've been actually following some of your posts.
     
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    If this were truly the case, then blisters wouldn't be a problem. You should also note, most insurance companies will not recognize a gel coat repair over a blister, insisting on epoxy instead, before offering coverage again.
     

  15. RufNutt
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    RufNutt Junior Member

    Ok i was able to get the gelcoat off of the boat up to the water line . I have not done anything for a couple weeks because I am waiting on the weather. I want to take the boat outside to sand down the laminate. Just thought I would post a couple picture as to my progress.

    I found that after removing the gelcoat from around the blisters there was alot of dry laminate.

    Just thinking out loud again was this a cause of blister juice evaporating in the heat . Like steam and then when winter hits it freezes and causes a void in the laminate of a big size in nature. Year after year it would increase in size. I was able to scrape of areas with little effort with my scraper of up to say 1ft by 1ft. There were no visual defects in the laminate it was not bubbled out , it just did not have a good bond between gelcoat and laminate. Plain and simple. The glecoat was very thin in places etc and very thick in others not a very good spray from the factory. I must say to the gelcoat never looked very healthy .

    This is just a picture of where I am at
    [​IMG][/IMG]


    In this picture you can actually notice the laminate gets alot lighter in colour as it gets out of the water. On the bottom of the hull or from water line down it is pretty dark looking in colour and has alot of dry spots. Also as I got closer to the water line the gelcoat had a real good bite. So i am not going any farther with the stripping I am happy with the bond above the water line.

    [​IMG]

    Time to start the sanding and fairing.I only have a couple areas that had actual voids and that would be back in the the corners .

    Any pointers as what I can use for a guide coat after putting down some fairing material before I actually apply any epoxy for sealing the laminate. I don't want to compromise the laminate for an epoxy bond with a guide coat for sanding. Or do i just do my best and worry about guide coats for sanding after I get my epoxy down and do a final fairing .

    Would love to hear some tricks of the trade

    Thanks
     
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