New RX repair project - a 16 year old Viper 11 bottom..

[mahyongg]

Yeah, chemical solvent welding works, for real. The only problem is - I have a sheet of 30x20 oval area. I can not imagine for the life of me how the solvent will ever get (evaporate) out there! Thats why I would like to rely on the epoxy in this repair. Otherwise I would just smear it all with ABS putty made with Acetone, which is essentially nothing else but solvent welding..

I guess the combination of glueing bond strenght and mechanical bond will work - if anyone could tell me what kind of plastic the foam consists of, that would be interesting too. If anyone has a book about "how to find out which plastic is which" (there is one in existence, I just cant remember the name), it would be great to find that out. Otherwise solvent welding would make no sense either.. since welds between different materials are also a different story ;D

One thing I know for sure because I tried is that the bond between G-Flex and the RX foam is bombproof, to the point where the bond is stronger than the foam itself. And due to the flexibility of GFlex it stays that way no matter how you pound at it.. tried that too (with the small tip of a hammer..)

Cheers,

Jan

[sbroam]

I'm pretty sure the foam is also ABS. My Viper's patch was 8x30"+ - no issues. My biggest patch since was at the end of a tandem canoe, more of a triangle - 20" or so at the base, maybe 30" h. No issues. That was put on about 2 years ago and has been suffering the abuses of kids at YMCA camp, novice river paddlers, adventure racers (been borrowed twice, finished first in class twice!), and baking in the sun (well, in the shade of an aluminum canoe).

Actually, now that I think about it, the latter patch didn't involve any cement at all. I used an oil drip pan (1/2" deep?) filled with acetone to soak the sheet of ABS. When it got soft, I just laid it in place. It was a hot day and you could see bubbles forming under the ABS as the acetone tried to boil off so I'd poke them with a needle. I don't know if I'll do that again as I made a mess on the driveway... It's not the prettiest patch, but it is solid.

[mahyongg]

Sounds great. Yes, indeed, several producers state that Royalex has an ABS core although I can not find any reliable source (for example the manufacurer.. ). Does anyone know such a source?

So did you do those repairs directly on the ABS foam or on the (albeit broken) ABS surface? Its hopefully not that grey stuff coming off in your Picasa gallery, is it?

;D

Jan

[sbroam]

When I get to a proper computer, I'll review captions. I have some recent pix of 10 year old repairs - PC7 and goop - the PC7 is solid, the goop just starting to let go. I know there are also pix of ABS putty applied when it was too hot out - it "flashed" (solvent boiled off to fast).

[jnorto01]

I'm in the process of repairing my Zoom with ABS goo made by melting black ABS pipe with acetone. I had an area of damage with foam core exposed. For large areas, build a plug to fit inside of your boat to support the area being repaired as the repair material will soften the boat in the process and may distort/melt it. The trick here is patience. You need to work with thin layers of repair material and wait 1-2 weeks between applications. For the first layer directly applied to the foam core, I used a thin skim coat applied with a tongue depressor and an auto body squeegee. This seals the foam core to stop it from soaking up too much solvent and provides a good base for subsequent layers to bond to. The mix was ABS goo 50:50 by volume with glass fiber fill and a bit of MEK added to slow the flash rate and extend working time. I let this dry two weeks. Sand with 80 grit sandpaper using a random orbit sander between applications. Next layer was the same goo mix (about the consistency of organic peanut butter, thick but still runny) smeared on and then a layer of S-glass added over top. Wet out the glass by squeegeeing the goo though the cloth with an autobody sqeegee. Let dry 1-2 weeks, then apply next layer. Between layer application and dry time, I have noticed (and expected) shrinkage of the repair material. This means it is curing well after it appears to be totally dry. I think this dry time is needed for a really good repair. I have 1 more layer to go on the Zoom.

I was planning on posting this after I was finished the repair and had several runs with the boat to be able to evaluate how well it worked, but I figured it might be helpful to go ahead and post.
For really big areas you may need to mix the goo with more MEK to extend the working time and enlist a helper to be able to get the goo on and wet out the glass especially if it is hot. Make sure you are using an organic vapor respirator when working with this stuff. It is pretty nasty, especially the MEK.

Good luck with your repair.
Jim

[mahyongg]

Wow, that souonds like some good job. So far, I always applied ABS goo in very thin layers that harden in a day or so, but it still takes long. Some small repairs had been hard enough to fend off rocks that scratched the surrouding R84 surface after a day.. which I thought to be sufficient although harder could be nice. I thought about using fibres in the mix too, maybe I'll experiment with that, I have some fibre leftovers.
Using MEK to slow down the hardening sounds like the critical point to me, as my ABS goo always hardens too fast if I try applying it to a larger area. But MEK is nasty as you said, I would have to buy a gas mask.. so I'd rather not use it.
Anyways, let us know how it all worked out in the end, I guess after what you've said its gonna be working (at least the bond to the foam should be good - but thats good with GFlex too, given the structure of it. You'll always get structural failure of the foam before glule failure there..).

Cheers,

Jan

[ncdavid]

I did some large area repairs to a Whitesell Descender. The areas under the knee pads were trashed. I cut away bad material until all that remained was the interior layer of vinyl with the thinnest possible bit of ABS adhered to it. Foam core, outer ABS, and exterior vinyl were gone. I applied many layers of ABS slurry, saw that that would be insufficient, softened some ABS sheet in acetone and applied it, then covered with many layers of slurry. I allowed a few days drying time between each step. And still thought I'd messed up. It was summer time and every time the boat got hot, the repairs would feel soft. Spray some water on them to cool them, and they felt firm. Eventually, like after several weeks, it cured enough to feel firm all the time. When I passed the boat along to another paddler, the repairs were as solid as the rest of the boat. I'll go more slowly next time.

[mahyongg]

Wow, seeing you replaced all those layers with solid ABS (you can get fairly thick 5mm sheets if you want to..) I wonder how much weight that gained?
Just thinking here.. if we could use that boiling effect when heat-gunning ABS slurry to (layer) create a solid foam, that would make a great center layer for such a repair. Light, too. Or maybe just use airex foam, that should work as well..

I'll experiment with that foam. Sounds funny enough to try.. just not on a boat (yet!) and I wonder if it will be structurally sound to do so.

;D

[mahyongg]

OK final report, all work is done & cured, the boat was tested yesterday and scratched already - G/Flex filled with microfibres and colloidal silica is more scratch resistant than (16-year old, well-cured, thick and ancient Mohawk) Royalex.. check out the last repair pics here:

http://www.ipernity.com/doc/mahyongg/al ... 1277466437

Cheers,

Jan

[jnorto01]

Nice job Jan. Very skilled repair.
Keep us posted on how it holds up.
The structural repair is done on my Zoom. It just needs a little paint to be put on the water this weekend. I'll report back after a few runs on how the repair is doing.

Jim

[mahyongg]

Thanks Jim, I will. Unfortunately the Viper couldn't come on the paddling trip this weekend, so we'll have to wait some more for new scratches...

[mahyongg]

The owner put the Viper through the paces once more, hit some more rocks, still holding strong! Some scratches even but nothing serious, behaves as you would expect. We're happy ;D

[mattm]

did a g-flex and glass repair on th efront of my encore. so far it's working well, hit a couple rocks and so far so good. Nice flexible resin after curing, I'll save the rest for my millbrook and use my epiglass on the sailboat. ABS slurry is good for coverage, but not good for structural.
http://good-times.webshots.com/slidesho ... 3286LOqVPz