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

    Again, it depends on the formulation you are using. As a rule, treat all epoxy the same way and you'll be fine. Assume you have a blush, wash it off with a mild soap and scrub with a Scotch Brite pad, rinse and dry - you're good to go. The only time you don't need to do this is if the epoxy is still chemically active, which for most is 12 hours. Some say as much as 24, but I've had issues with 20 hour old cures having a blush, so unless it's 12 hours or less, I let is get hard and scrub. If you're waiting days, before getting at it, the fairing compound is a lot harder to sand and you surely what to check for blush.
     
  2. RufNutt
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    RufNutt Junior Member

    Par again thanks for the advice, I will try and work in them time frames. Temperatures should be starting to work with me soon. My biggest problem when I do anything is I prepare for the worst and our temps are just not right if the power goes out and I loose my heating source working with epoxy. I am just getting geared up with some other heat sources just in case. A couple more days of sanding and picking should be able to start laying down some material .
     
  3. RufNutt
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    RufNutt Junior Member

    Hello again I just wanted to make a post on some findings I found when I was doing some readings on blister repair failure. Here is a real good article here and it looks exactly like my hull.http://www.yachtsurvey.com/BlisterRepairFail.htm Really to me stripping the gelcoat is the only way to really fix any amount of blisters. I never had really that many on the surface in my opinion, but after removing the gelcoat I found a mess in the lay up layer. This boat is a 1994 and had seen lot's of water. I am making progress but again unless you have lot's of patience this is a big job but really the only way to try and make a boat out of it. I went over to the dealer here last week they wanted over 30,000 dollars with tax for a new boat the same size and same options I have. My nephew just bought a new one last year... Just got it out from winter storage and he told me it is going in for delamination repair and has already had repairs on the outside after a month of owning it and they were manufacturer problems . I would be irate at the price he paid . Oh well I might have 4500 into my full restore when I am done and no what I have in the end. But again I can see why a professional would have to charge so much that most people just drive them to the recycler for scrap

    Thanks for all the advice
     
  4. alan white
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    alan white Senior Member

    Wow... if you got all that gelcoat off in an afternoon, it sure is a good idea that you stripped it off. Meaning the gelcoat had a serious bond issue and the whole boat should be likewise stripped. Normally, even with a heavily blistered hull, the gelcoat wouldn't come off like that.
     
  5. PAR
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    PAR Yacht Designer/Builder

    Sounds like this is a bad hull laminate or a screwed batch of resin, possibly both. Attempting to save a questionable laminate is risky, to say the least. Fixing blisters is one thing, but the photos of that laminate show wholesale issues. At some point you have to cut your loses. What percentage of hull area are resin "dry"?
     
  6. RufNutt
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    RufNutt Junior Member

    Alan the stripping took like 3-4 days not an afternoon.I was also thinking about stripping the whole boat . Do you think I would have to go with the 3 coats of epoxy above the waterline for sealing the laminate too?

    Par as for resin dry it is not dry beyond the lay up layer,most of it looses it's dryness before I sand through the lay up layer. I am actually pretty happy with it . And actually the only areas that are resin dry are from the chines accross the bottom of the hull, maybe 25% of that area and more on one side then the other. Just going to be alot of work . Actually looking at the hull with a light under it , it looks like they used 2 different types of resins right accross the bottom of the hull to the chines. Because the next layer in is alot darker in colour. You can actually see where they quit spreading it. As per cut my losses I don't think I will as I redid the interior first as the boat never looked that bad and I would have not noticed this problem if I just sanded and painted but I decided to strip it. If I have problems with blistering down the road I will just say oh well I tried . I used the boat on the water for a full season before I started this and had no complaints is why I decided to redoe it . Oh and did I say or maybe you might have figured it out I am too stubborn to quit :)
     
  7. PAR
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    PAR Yacht Designer/Builder

    Well, you're the one you have to please and having some stubbornness is a good thing.

    Yep, 3 coats of epoxy are necessary. Two will probably work, but there will be some areas, that 3 are necessary and you're looking to build film thickness too, which is why 3 coats is the usual recommendation.
     
  8. RufNutt
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    RufNutt Junior Member

    Just one more question, by my findings they basically want me to take off the lay up layer ( chop strand) down to the laminate as they say there is no structure strength to this layer as it is just there to hide the print through of the laminate layer. When I get to the laminate layer I will start to see the pattern . Should I sand down the laminate layer to get rid of any bubbles in the resin rich areas that are in the low spots of the laminate or should i fill these areas with a fairing compound. I figure I should do as little sanding to the laminate as possible as this is the structure layer. Just looking for some thoughts here.

    Thanks
     
  9. RufNutt
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    RufNutt Junior Member

    Cleaning up a hull it is alot of work. You must have experience using a sander and be able to read the different layers of the hull for when you are sanding. I used an aggressive 40 grit sander and I sanded down the lay up layer down to the laminate. Read the guide I posted by someone else it is very informative . The lay up layer must come off. I am left with an excellent base to start off with. Just think of it as stripping a car down to the metal. It is alot of work but the only real way to do a full restore. During my sanding process I would take off a little bit of layup layer and it would start to weep. There were no signs of weeping prior. After I got all the lay up layer off it has no weeping signs anywhere. So the report that I posted is right . By just doing spot repair you are missing alot. If blisters start to show up the damage or problem is already showing it's sign and is far beyond them few blisters.

    I think the biggest problem with this is climate especially when you live in Northern climates as your boat does not get to dry out from the season and it freezes expanding these areas even farther for next season. Probably why the gelcoat come off like it did in some areas( weak form the freeze thaw cycle) That is the problem up here. It is like when car manufacturers or aftermarket manufacturers talk about certain options or products in cars . Bring them up here for a couple years we will put your products to test with the freezing and salt etc. it is a different beast up here with the seasons. This is not a repair for anybody, you must be committed .
     
  10. RufNutt
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    RufNutt Junior Member

    I am finally getting ready to start to fair the hull but i got a couple repairs I want to take care of first. There was some rashes along the keel about 3 inches by 12 inches. I had to take off 3 layers of laminate to get to good laminate. So i took off a little more then an 1/8 of an inch and there is probably only 2 layers of laminate left. So the hull must be 5 laminates thick. I never worked with epoxy before and in my readings I am finding you do not use csm with it like with ployester.

    The question I have is I have some 6 oz E glass plain weave cloth and some 1708 biaxial. What would be the best solution to fill in the laminate. 1/8" or .125" of 6 oz cloth is about 13 layers at .0093 per layer and if I use 1708 it is 2.8 layers. Would it be better to use the multiple layers of 6 oz or go with 2 layers of 1708 then fill the rest up with 6 oz cloth.

    The measurements I got for the 6 oz cloth was posted by the manufacturer and i don't know if that is wet out thickness or dry so I just used them numbers to get an estimate. I can't see it taking 13 layers .

    Now that I said this I just went out and checked and my inventory of 1708 is nil but I can get it pretty quick.

    Maybe someone has a better idea of cloths to use if what I have will not work.

    Thanks
     
  11. ondarvr
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    ondarvr Senior Member

    You don't want 1708, you want 1700, no mat.

    But it's not going to make much of a difference which one you use, both will be much stronger than the laminate that was there before. I would just go with what you have on hand.
     
  12. RufNutt
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    RufNutt Junior Member

    So are you saying I could get by with multiple layers of 6 oz or should I buy some 1700 since I am out of 1708

    I have lots of 6 oz here
     
  13. ondarvr
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    ondarvr Senior Member

    Sorry, cloth or 1700, it won't make a difference.
     
  14. RufNutt
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    RufNutt Junior Member

    I am just trying to wrap my head around strength of fiberglass cloth. Say for instance the boat builder used 18 oz matt as laminate layers. Would 3 layers of 6 oz cloth plain weave be compatible strength wise to the 18 oz matt. Even though the thickness of the finishes 3 layers of 6 oz cloth would be thinner. I am just trying to grasp the strength of products available today. I know I read alot about newer thinner clothes are as strong as older matt material. Is strength derived from the weight of finished material. I just can't grasp where they get the 6 oz weight because thickness wise it is not very thick.

    I am just asking this question to try to understand strength is all.

    thanks
     

  15. ondarvr
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    ondarvr Senior Member

    Since you are just rebuilding small sections of damage with cloth and epoxy don't worry about strength, whatever you use with the epoxy is more than strong enough to do the repair. Just build up the surface as needed and do the final fairing.

    If this was an entire new hull build then an evaluation of the strength of the glass (many types) would come into play. There are places an situations where one type will be stronger and work better than others, but each application needs to be looked at on its own.
     
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