Awkward repair

[doc]

Hi Jon,

Agree - while it would be nice to sand/fair the edges on every layer, I’d also consider the layer/layer bond:  it would be better if the resin hasn’t hardened enough to sand. Even with epoxy, As long as it doesn’t look like it’s a set of steps, all good. 

Now, if you’re using your first and quite narrow layer of glass cloth as a sort of filler, see how well the Gorilla Glue comes out for fairing/flatness, see if you need it at all. It’s mostly going to be filler, after all, not contributing a helluva lot to the structure. If you do go with it, I would do that alone, then sand so you don’t have any odd bumps or ridges. Don’t be afraid to sand it mostly away. I like the idea of a glass-glass scarf ( or scarph, as we spell it here in boat circles) but I dunno if you want to feather things far enough to make a really effective joint. If I remember correctly, doing that sort of joint in plywood you shoot for around 6/1 width/thickness, a similar ratio or greater would be good for a lamination…and hard to do. 

I would probably use a wider piece of carbon than just a couple inches, the more of the original bottom it’s tied into/bonded to the better.Cutting a slight curve in the forward and back edges is probably a good thing. Likewise the layers of glass cloth on top of it.  Maybe work your squeegee so you have the resin to (hard to describe) make the transitions less apparent?

Oh, and I don’t think it really matters what flavor of cloth you use. Yeah, there’s some tensile strength differences, but the carbon has a much greater difference. Shouldn’t affect things to any meaningful degree.

that help any?

doc…

[Jon82]

Hey guys

So I finally removed the deck pad,just to be sure what was under there.

The pics show how it looks. There are small cracks, which could even be just paint cracks, around the edges of my other repair job. But the deck is definitely intact and strong.

Just for extra strength, I’d still like to follow docs recommendation of a couple of pieces of glass across the deck and overlapping the rails. Would I just need to sand off the top layer of resin and paint on the rails?

I have a couple of sheets of 1000x600mm s glass cloth on the way. In the images you can see how much random carbon I have. I’ll use the carbon on the bottom. Should I overlap the rails the carbon? Should I put seperate pieces of carbon on the rails?

How do I best use the materials to maximise strength?. I don’t care about added weight.

Thanks again and happy new year to all

Jon

https://swaylocks7stage.s3.us-east-2.amazonaws.com/s3fs-public/F60D1841-BDD0-4565-A033-2111B27E0425.jpeg(image larger than 4 MB)

[Jon82]

Here is my attempt at feathering the edges of the carbon, after removing the damaged material.

Does it matter that I can lift the edges of the carbon? The edges are not ‘stuck’ to the foam. Would this be a case of getting the gorilla glue under there to create a new bond?

Thanks,

Jon

[doc]

Hi Jon.

Wow, that’s…unlovely. Hideous, even. 

A couple things I’m taking away from that. First off , the lamination-foam bond was nothing spectacular to begin with, Not surprising, as is mentioned in the parallel epoxy thread, styrene foam is soft stuff at best. And when a board flexes, as it does, that bond is in ‘shear’, when the bond is stressed  and the stiffness of the foam starts to matter. Here, well, the skin/laminations did all the work, the foam was more or less only along for the ride.

So, if you get some Gorilla Glue in under those edges, any bond it has will be an improvement over what was there.  It may act as an intermediate layer between the underlying foam and the far less flexy laminations. Where you have styrene foam that was a little melted, that developed a little bit of a skin or crust from sanding, that I would score a bit, scratch it with something like a fork. Really, a fork. That should improve the foam-gorilla-glue-turning-to-foam bond, I dunno that the GG will necessarily bond all that wonderful to the crusty bits, nor am I all that sure the the crust will hang in all that well all by itself. Think of it as similar to , oh, what used to be called a ‘scratch coat’ in plastering walls, an intentionally non-smooth surface that the next layer would stick to quite well. 

If you can, I would use wax paper as a first later on top of the glue, thin ply, something flexy like thin sheet metal and maybe some load straps, ply across the straight bits and flexy stuff around the curves, hold it on firmly with the load straps. Maybe a block ot two, on top of the ply and under the straps towards the middle for more uniform pressure That would act as a cofferdam or temporary mold to put a little pressure on the glue as it goes off. That will have two effects: the foam the glue turns into will be denser and stronger plus it may be forced into the deep cracks to a greater extent. And you’ll have less sanding to do to get the cured glue down to the feathered edge of the lamination.  As I say, ‘if you can’. It’s not essential. Pull it after the glue has mostly cured.

Then, laminate the hell out of it. 

that help any?

doc…

[Jon82]

As always, massive help thanks doc.

Like the idea of wax paper and ply over it while the gg goes off. Was going to use duct tape but of course your recommendation will be stronger and hopefully force the setting foam down into the crevices more effectively. 

 

Once I’ve sanded level the set gorilla glue, with a bit of a bevel for the new carbon to lay in, I’ll lay carbon over the lost carbon areas then S glass over that, around the rails.

Thanks again, will keep you posted how it goes.

Jon

[Jon82]

Well, we are on a 3 day lockdown here in Brisbane, Australia. Someone tested positive for the UK variant. Stay safe everyone out there.

Benefits of being home; into the garage for repairs

Thanks Doc, the gorilla glue went well. Very happy with the result so far. Rails look great, where before they were a total mess. Wet bits are where I’ve just added a little more gorilla glue to fill some holes that were left after sanding.

Was able to get a really nice seamless fair job with the glue. Definitely can’t get my finger under the edges of the glass now.

Still waiting on my resin and S glass in the post but red for laminating when it arrives.

Jon