Help/advise with epoxy delimitation in Stitch and Glue Center Console

Discussion in 'Boatbuilding' started by johnnythefish, Nov 12, 2017.

  1. johnnythefish
    Joined: May 2016
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    Location: E.A.

    johnnythefish Junior Member

    So what was meant to be a simple transom extension has changed into a major rebuild at the very least.

    Whilst I had the engine off to extend the transom, I decided to do a few modifications to my bilge. After grinding through some paint (so I could glue in a mounting block for a bilge pump), stinking smelly greasy grey water started seeping into the bilge from under where I had opened up the paint on the port side of the keel.

    About 5 liters of the stuff came weeping into the bilge; on further inspection/digging and to my alarm I realized that I can slide a hacksaw blade all the way under the motor well bulkhead and the port stringers.

    In the transom lockers, I had noticed a small crack where my chase tube comes out; water would sometimes get in here (I guess from where the hoses come into the transom well).

    I decided I better open this up and check if there was any water in there; and whether this was the cause of my problem.

    Well the PU foam was a little damp near where the chase tube came out - didn't think much of it till I dug all the foam out and there was a pool of water about 10 liters right at the bottom.

    More frightening was that as I was pulling the PU foam out, it was pulling up the fiberglass laminations with it.

    I decided to cut an inspection hole in front of the motor well bulk head on the port side; so one frame in front of the leaking transom well.

    This is a total disaster... on cutting the pu foam out, you can litterly squish the fiberglass up and down.

    I cut through this layer with a box cutter knife and to my horror, it appears that all the fiberglass has delaminated from the ply.

    This is worse than just a gap under the stringers. This means that the entire inner layer of biaxial (which makes up the "monocoque structure" has delaminated.

    The epoxy has turned to a sort of dark brown gooey, sticky grease; it was rock solid dry when I poured the foam 5 years ago; is this some strange chemical reaction?

    Has anyone heard of this before.

    Does this mean I am going to have to rip out all my stringers and frames?

    How do I prevent this in future?

    I have posted a video on you tube as I couldn't figure out how to post videos here on the forum - the link is and I will try and post the rest of it as soon as I can get fast enough internet. Cant get the other part to load at the moment - but if you poke around on "my channel" you will get enough of an idea.

    To sum it up, on further investigation, I think that issue is far worse than I had initially thought.

    I have opened up the sole towards the front of the boat and basically the delamination has pretty much spread everywhere. I am posting another video now which shows that the biaxial fabric is even lifting off the hull sides high up in the front locker of the boat.

    I think that this is obviously some sort of failure/ strange chemical reaction on the part of the epoxy; and may or may not be something to do with the water in the hull - I am still in two minds over this.

    You can see in the video that it is like the epoxy has broken down, it is sticky and gooey and I can smell amines; on places where it was on the ply wood, I can literally scrape it off with my fingernails.

    I would never have carried on building had the epoxy not cured initially, so there must be something going on.

    I know that the outside of the hull was sheathed using Ampreg 21 (www.gurit.com/sitecore/content/Old-Prod ... mpreg-21SP)

    As I recall, I ran out of that and I believe that the inside was done with Atul Lapox B11 and K-41 hardener.

    Which as I recall, this was very viscous and I may have mixed it and then placed the pot in a tub of hot water to lower its viscosity (which I believe is an approved technique) in order to get it to wet out the glass.

    I live in a place where this is the only resin available, and I believe that I did run it by the designer at the time.

    Unfortunately, the whole inner biaxial fabric was laid in the same day, so what ever issues stem for the resin, they must be pretty universal to the whole sheathing.

    Having said that, it surprises me, that there are places which are firm and strong (perhaps a better mixed batch from the same day, or the water never got to that part)...

    All this is fairly mute at this stage, as I really can't see any other solution than to gut the whole inside of the hull, and hope that the outside, with the different resin is fine.

    As far as the plywood goes, it still seems pretty solid, with no signs of rot.

    In any case, I boil tested all the samples... before building - as I am not convinced the BS1088 stamp was genuine!
    All plywood used has stood up to one hour of boiling, a night of freezing and an hour of boiling so far, so at least the glue is strong

    All I can say is that this is all pretty devastating...

    I was certainly under the impression though, that once cured and hard, epoxy was fairly inert; and that other qualities aside like viscosity, cure times etc, were more of a luxury to the builder than a necessity to the integrity of the boat.

    As I said before, there is no way I would have continued building with semi-cured resin... and all my resin samples were tested before laminating to make sure that they cured.

    I guess you live and you learn; and as the saying goes, "worse things can happen at sea".

    Personally, I am strongly questioning the logic of adding PU foam and completely trying to seal the various lockers.

    I think that next time each compartment between the frames will have a drain plug that allows any water that may have gotten in there to flow into the keel section.

    I would of course appreciate all thoughts on the subject - I suspect I have to gut the whole insides?
     
  2. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Moisture test Tom. Wet on the bottom; the boat is done.

    Boats with foam that are sealed have no reason for limbers. I have gone in circles with people on this issue and the bottom line is you need to know if you have ingress, so inspection pie eyes of holes are useful, but allowing water to move about the bottom is not going to help unless you want a wet bilge. I have always questioned the use of foams in ply boats, but I'm not sure the foam has anything to do with your problems.

    After reading your post here, I would be suspicious that you never got your inside glass wetted well enough and had dry spots in the laminate where rain actually washed into the lamination. Given viscosity problems, did you wet the plywood first? Dry joint also becomes a real concern. I am not your expert Tom, but I can help you keep the thread at the top for some other guys to help with opinions.

    I don't get at all how you have ingress in the forward locker...very strange.
     
  3. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    Just for clarification, did YOU build the boat ? IS it Epoxy for sure, or Polyester ?
     
  4. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    He built it. He states the epoxy he used. Different in n out
     
  5. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    I checked and see the viscosity of the Atul ... is 11,000-15,000 cps. That is on the order of 20 times more than the stuff I am using and sometimes I wonder if mine is too thick.

    Not sure how thin you can make it via heat, but I'd guess by half, which is still very thick.

    I don't have enough experience with resins to know what the results of using too thick a resin would be, however, I have tried to caulk with cold caulk that won't move well. It tends to stick poorly to the substrate. If you used a thick caulk on each side of fabric; it'd stick poorly to the fabrics and perhaps layer the fabric without bonding to itself on each side. Could you have experienced something similar where the glass didn't get wetted through well enough?

    Perhaps someone here knows what happens if the epoxy in a build is too thick; I'd be guessing, but it seems like trouble.
     
  6. johnnythefish
    Joined: May 2016
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    Location: E.A.

    johnnythefish Junior Member

    Many thanks to everyone for their responses; yes, I built the boat, and yes the epoxy - or whatever it was, was very think.

    I am continuing to demolish the innards of the boat as we speak. I suspect that there were issues with the epoxy - like I said, materials are much harder to come by over here - lesson learnt!!

    I will keep you posted as we go; at the very least, the whole stringer and frame network will have to come out and the hull cleaned and relaminated...
     
  7. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    Good luck Johnny. A good hint I got off these forums is to use a small heat gun to lower the viscosity of the Epoxy to ensure better wetout of the fabric. It does help a lot.
     

  8. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    Try to dry it down better than ambient. Get a meter and reglass only when arid.
     
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