Huge screw up. Failed vacuum what?

Discussion in 'Fiberglass and Composite Boat Building' started by Ctowles, Oct 13, 2013.

  1. Ctowles
    Joined: Oct 2013
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    Location: Jackson hole, wy

    Ctowles Junior Member

    Im building a ww dory currenty built out of 1/2" and 5/8" corecell with a honeycomb interior. I have been vacuum bagging all parts as i go. I did the insides of the panels in big bags on the shop floor.. Easy breezy, no troubles. However, after i bent the panels to shape and glued on the floor, bagging the 17' side panel became much more difficult. I tack taped off the preglassed interior gunnel line, and used the transom stem and chine tape that was laid up by hand to seal the top of the bag. The first panel was hard to get a good seal. I chased leaks for a good 5 hrs before i gave up and let the bag sit at 13-15 hg.the panel came out good enough. There are a few areas that look like dry spots, but i think they are just a bit more white because there were large air bubbles in the lam that got squashed and the excess resin and poly fabric were a bit off color. The second panel was a disaster tho. I laid up the three layers of 12 oz biax, poly, and 9oz and wet them out. Getting some of the large bubbles that form flat is something i can rarely seem to do successfull no matter how hard i trowel or bubble roll. Usually the vac bag squashes it all. Well the second layup i was not able to seal the bag. Most i could pull was 3" hg. I tried to find leaks for the better part of 6 hrs to no avail. I tried a stethascop and no dice. It sounded like my thru bag connector was leaking like a sieve but no amount of tack tape, duct tape, etc seemed to do anything. I tried to find leaks along the tack line, without much success. After hours and hours of searching, i gave up. Looking bag, i should have yanked the bag, pulled the precured glass off, taken a few hundred dollar loss and started over. But no, in the back of my head i though, its just a hand layup with peel ply, it will be ok. Well, i pulled the peel ply today and no surpise found quite a few decnt size air bubbles in the lam, as weel as several spots along the gunnel and chine line where fabric either folded and stood up pround on the chine, or just was not bonded to the core at all like at the gunwale line.. Obviously this is a potentially build ending mistake. What do i do now. I did my best to ensure the bare foam got epoxy so i think the bottom layer of 12 oz biax is ok in alot of spots. Seems the bubbles are in the top 2 layers of poly and 9oz. They seems fairly stiff but if i press hard enough i can feel a bit of movement. I am worried about the structural integrity of the panel in these spot.

    What do i do now? I should have bit the bullet and ripped the layup off before it kicked but i didnt. Now i imagine there is no way to remove the skin. Which sems like i now have 2 choices..cut thru all the chine stem and transom tape with a grinder and remove the entire panel and start over. This is costly and i literally might send h boat as it is to the dump rather than spend another $1000 in materials.the other option is trying to grind hru the laminate to the core in all the bubble spots and do like 20 spot repairs and then try to lay one more sheet of glass over the top to cover up the mess. What do u all think. This is a huge screw up, but i dont know how i could have prevented it other than mabye some kind of double tape seal. Only cheap material i used was breather out of poly batting. Otherwise airtech film, p3 release, and tack tape. Thru bag fitting is airtech also. Anybody ever screw up this bad, and what did u o to fix it
  2. Charly
    Joined: Dec 2009
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    Charly Senior Member


    A picture is worth a thousand words
  3. Ctowles
    Joined: Oct 2013
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    Location: Jackson hole, wy

    Ctowles Junior Member

    Ill try. Spent about an hr trying to figure out how to link to flickr. They canged their site and policies and wont cough up the bb code
  4. Ctowles
    Joined: Oct 2013
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    Location: Jackson hole, wy

    Ctowles Junior Member

  5. latestarter
    Joined: Jul 2010
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    Location: N.W. England

    latestarter Senior Member

    *You got your photo to work while I was writing the following:-

    You can upload photos from your computer on this site.

    Click on "post reply"

    The "Reply to Thread" page comes up, click on the paper clip symbol.
    The Manage Attachments screen pops up. Click the browse button and navigate your way through to your pictures and select the one you want with the open button. When selected, click the upload button. It will add a thumbnail to the post. Takes a while for me as I have a slow connection.

    Some sites do not let you upload photos until you have posted a certain number of posts, I do not know if it applies here.
    Last edited: Oct 14, 2013
  6. Ctowles
    Joined: Oct 2013
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    Location: Jackson hole, wy

    Ctowles Junior Member

    A little followup. I went back out late last night to look at it some more. It was a tough day yesterday realizing i screwed up so bad. Really should have just yanked the precured glass and started over but its too late now.

    The bubbles do not look like they could be filled. I took w flashlight to them and there is plenty of resin in them, i can see microscopic air bubbles in the glass. Its not like there is a huge air pocket i could syringe epoxy into. But Just cant tell if the air bubbles are in the layup between the layers, or voids against the core betweenthe corecell and biax at the bottom of the layup. They defintly are bubbles and are easy to see and feel. I dont know if there is any remedy here other than the dump. The chine is taped with kevlar tape, and 12 oz biax. The side layup of 12 oz biax/poly/9oz goes over the joint too. I havent laid inside fillets yet, hull is glued to side panel tops right now. Trying to cut it out and start over is probably impossible or a job that would take too much time and money to accomplish. Any ideas, starting to feel like its hopeless and may be time to just admit defeat.
  7. Tungsten
    Joined: Nov 2011
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    Tungsten Senior Member

    Geez sounds like your in the dumps!!

    Not to worry Chris,grind them out, fill them flat no one will no the difference.

    My guess is the lumps your talking about is the individual tows of fiber get bunched a little creating a lump or bubble.Pulling on each end of the strands will make them lay flat again.Troweling across the glass creates them.

    Did I read that lay up right? 3 layers of 12 then poly?? then 9 oz
  8. Ctowles
    Joined: Oct 2013
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    Location: Jackson hole, wy

    Ctowles Junior Member

    Mabye ok...

    Well, tungsten i think u are right. While its a big screwup, this is a glass boat. Just about anything can be fixed right, thats why i chose to build glass.Mabye i was overreacting, but i originally thought all those areas were unbonded core. I did quite a bit more investigating with a headlamp and it looks like many of the bubbles are areas of microscopic air bubbles and resin sitting between layers that like you said had the bias pulled a bit by trowling. Investigating what i thought were dry spots on the other bagged side panel, i found most of those spots where actually just like the other side, areas that the bias got pulled and bubbled but the vac bag squashed the fabric. They arent dry at all. a bit of microscopic air trapped, but the other side looks and feels good and has a nice finish. The poly fabric also stays a bit white, it doesnt wet out like glass, so if if its not sitting even in the layup itll look w little whiter. I had at it a bit with the sander today. Amazingly enough, alot of my supposed bubbles were areas of excess resin poolling and making bubbles in the peel ply surface cap. I think the bag had just enough vac at 3" or so to kind of hold stuff better than just if it were sitting there, but not enough to evacuate resin. the peel ply was wet out but not much got thru the bleeder perf ply. The big ones in the pic are the worst. There are 2 small ones near the tansom and 1-2 near the stem, but prob only 10-12 real areas of bubbling at the surface. I sanded into a few to level them out and figure out where these bubbles are. In checking over really close with the light and a loupe, it seems most of these bubbles are in the intermediary layers of the layup and not unbonded to the core. THe bottom layer of 12 oz biax Had a ton of resin and was fully wet out when i layed the top poly and 9 oz layers. I think these bubbles are at this inteface and not at the core. As far as i can tell there are no areas of bubbling or voids against the core so mabye i dodged a bullet and can repair. The only areas of unbonded core re by the gunwale line, ill trim to shape, wick in a cab glass bubbles mix in to the gap, clamp it with like 12 clamps and not worry since it will be glued and bolted between wood gunwales.

    So as to the fix, ill likely do what you said. Sand more to level the panel. Then with the longboard to even the finish. This should take care of the high resin cap spots and the top layers of the big bubbles ill know what i am dealing wi for bubbles at that point.. Any bubbles that i can push and feel movement i will grind or sand thru till i get to good glass or core. Ill then try to vacuum bag repairs in sections replacing layers i ground out.. Then sand flat and do a light fair coat of the panel and sand. Then i can do the big bottom layup. Once thats done ill add another layer of cloth to finish the side panel, probably on both sides.. 6oz or 9oz whatever i have extra of. Little extra glass never hurts, im building beefy. Ill bag that and at that point the whole boat will be glassed so mabye easier to seal off the bag on the panel face without having to tack off the inside gunwale line and all the pleats and potential leaks that go around it. That should give me a nice bagged surface on both panels easy as pie to fair out. Sound about right boat building experts?

    Ive been loving the squashing action i have been getting on fabric wi the bagging otherwise. Seems i can really clamp stuff down and make nice flat even surfaces with overlapping fabric and the like. Up until this panel i have been getting really good results on both large and small panels. Guess i need to just not give up hope. Its just a boat, and im building it, so i can fix it. If i couldent, id be screwed when i eventually break it on a rock. Lifes good, keep building...right? headed back east for a week for a family visit, when i get back ill resume grinding, glassing, repairing, and bagging. Ill update the thread with my fix.

  9. groper
    Joined: Jun 2011
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    Location: australia

    groper Senior Member

    Keep it simple, your over thinking it... grind out the raised sections and bubbles and places where there are big voids.
    Vacuum up dust after the grinding, then mix up some resin with cabosil to thicken it up like peanut butter.
    Use a paint scraper and trowel it into the voids you ground out and tool it off flush. Whilst the peanut butter is still soft, laminate over the whole panel with another layer of glass to replace any lost strength.
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