ABS slurry questions

[Jim P]

I just did a rebuild of my Ocoee. It had de-laminated under the entire center of the boat, around the chines and starting up the sides. it was open and leaked water into the core. I cut off the whole mess down to the foam core. The core was cracked, some chunks fell out, a bad scene. I let it dry for a month, then applied a couple of coats of the slurry to fill the voids and get a reasonably smooth surface.

I did cobble together some inner hull support for this project just in case things decided to collapse.

Then I applied the slurry with three layers of 6oz glass cloth (no kidding you have to work fast). I did it my making the slurry THIN, then slooping a small area of the hull (about a square foot), then working the glass into the paste. Be sure to get the glass saturated and squeeze out any extra. I used a putty knife for this. Get some refinishing gloves, vinyl, nitrile, will melt. Allow each layer to dry a few days before applying new layer. Each layer of glass is a bit larger than the layer under it, overlapping the original hull at the edges.

When done I put on a thin layer of Slurry, dried and painted. The finished hull is not a smooth as the original but it is stiffer and the boat weight seems about the same.

Took her out for the first time Saturday, hit lots of rocks, lots of scrapes and a nice long crease in the bottom, but it looks like it will hold up well.

[mattm]

hey NZMatt. The acetone is fine. I'm no chemist but have worked in a machine shop for too many years now. MEK is known as nasty stuff. A scab during the last strike put some on an ear swab to clean his ears and went deaf. Bought .125" dia. ABS weld rod from USPlastics.com. 2 pounds was $35 U.S. incl. shipping.Easier to cut up than pipe. Your shipping is probably more but your dollar is probably stronger than ours too

[MotorCityOC-1]

Sportsfans,

I'm concerned that if I lay up some layers of glass using ABS slurry, the slurry won't properly penetrate the yarns in the glass, and the area will be weaker than it would be with ABS alone. Any thoughts?

Also, I've always thought that in laying up glass, the purpose of keeping the amount of resin in each layer to a minimum was to keep the overall weight as low as posible and the strength to weight ratio as high as possible. Assuming that ABS is stronger and lighter than the same volume of epoxy resin, doesn't it follow that a little extra ABS in each layer (e.g. not squeegee-ing) isn't exactly a tradgedy? In other words, ABS isn't as much "dead weight" as epoxy resin- is it? Doesn't it make sense to err on the side of wetting up the glass thoroughly? If the layers are a bit thicker- what's the big deal? (blistering aside)

Lastly, can anyone point me to some decent directions on how to put on layers of fiberglass? Even cutting the fabric on the bias, I don't see how I can cover a complex shape like the stern of a canoe without either wrinkles or relief cuts in the fabric. Is it an overlapping bandage kinda thang? I've searched the inter-web and not found a page called "Fiberglass Repair For Dummies"...

Thanks,
Kevin

[Jim P]

I think you are correct that a bit of extra ABS will not hurt the repair. The key point is to saturate the glass. The glass will make the ABS stronger - my thought is it will be like reinforced concrete - it should resist cracking and be much stronger than ABS alone. I squeeged out extra abs to make a more consistent patch and to try and make the repair a bit lighter since it was over such a large area. In order to saturate the glass I used a slurry that was thinner than paint. Why? Because the acetone evaporates quickly and if you start with a milkshake your working time is too short to ensure you can work it into the glass before it sets up.

Of course all of this is charting new territory as I've not seen this done before and how long it will hold up etc. is unknown.

Cutting - I did a couple of relief cuts to make the corners on the chines. I only needed one small cut in each layer and made sure I layed it up so the cuts were in very different positions for each layer. Not sure how to do it otherwise.

Good Luck.

[yarnellboat]

Good info, my bow is a mess and needs a crunch pad...

For surface prep - to what layer do we apply the slurry?

My bow has some dents & cuts that expose the foam core - do I remove the foam core as someone mentioned above?? Or should I fill the bangs with 3M adhesive or other epoxy, or with the slurry?

Once the dents are filled, I'll remove the outer vinyl and use some slurry & glass.

PY.

[philcanoe]

.....

just MHO.. never have used the stuff, but have built at least 60-70 boats

I would try wetting out cloth then applying, only after it is totally wet out... in this manner you could always re-wet the curing ABS with acetone (if it indeed drys this fast)

you keep the cloth to resin ratio high as possible - because the resin is the weakest component... when a FRP composite hull fails, the resin typically fails before the fiber(s)

i would assume that ABS is NOT stronger (but that's not why it's desirable) and not sure what strong is a definition of

again i haven't weighed it - but that weight thing may not be true, especially when considering the amount used of each in order to accomplish the same task

what's the big deal? blistering and deterioration of the hull, the foam in particular

as to how to lay cloth... practice cutting shapes and sizes, and laying them in place while dry... you can attempt with some cotton cloth first, but the fiberglass will handle different... however they can be used as a pattern for cutting the fiberglass... also most likely you'll need to piece and overlap, as speed and inability to readjust sound like a real considerations... and yes on the bias

now...

i'm not sure i'd really try laminating a layer of fiberglass cloth anyway... my preference would be to try adding cut fibers, to a slurry of ABS... not trying to create a stiff outer, but merely adding reinforcement to the ABS... this might really add compressive strength to the outer layer, or increase tensile strength of inner layer, and add some abrasional resistance... and instead of peeling off in a single layer, this might tend to stay on a hull better

[yarnellboat]

Here's a bad-news update related to the idea of using glass cloth with ABS slurry...

I fixed my bashed-up bow with slurry, and added some slurry-soaked fiberglass. I was happy with it for a year I guess. This sprping I gave the nose a real full-speed straight-on knock, and the repair bubbled - the ABS & glass were lifting from the repair. I started poking around at it, and the whole ABS & glass scaped off quite easily. I think it would been better to just leave the ABS paste alone, or to finish with glass & traditional resin over the slurry repair.

Have others had success with ABS slurry & fiberglass cloth?

Also, after emoving the glass & Abs I cut & tidied and the area and went with another ABS slurry - although it worked fine the 1st time, this time I've managed to soften the nose of my boat.

Not sure what the difference was, maybe I got cocky and put it on too thick or put additional layers on too quickly, but it didn't seem like it.

I'm running out of bow! The inner ABS is showing through in places where the bashed foam has fallen out or been cut away, so I'm basically through to the very inner layer of my boat. No nose left.

I think I will have to kevlar the inside for starters. Then I may fill with 3M urethane adhesive or Aquaseal (having lost my confidence in ABS slurry), and then glass up skid plate that will probably require patching with some frequency. Drag.

Summary: slurry with cloth didn't work for me; and slurry is not fool-proof, as it worked fine for me once, but made things worse this time.

PY.

[MotorCityOC-1]

my adventures with slurry went badly, probably because I failed to use the ridiculously thin coats required. using enough slurry to wet up any kind of woven cloth would likely be too much slurry in one "coat", and would lead to melting the good ABS underneath, bubbles, and general mayhem.

on the other hand, my adventures with West System G-flex went really well- using a paste of G-flex and silica filler powder to fill in rotted spots in the foam core, and laying up a couple of layers of fiberglass and G-flex over the whole area.

so far the only downside I can find for G-flex is the cost...

[bambam]

Does anyone have any photos of the work they have done. Step by step or even just the finished product? Thanks!

For way too much information, I just published a page here:

http://docs.google.com/View?id=ddbj2z7h_18qtbc2qhg

Hopefully that link will work -- I've never done that before.

Couple-o-points:

ABS pipe is a foamed extrusion and hasn't worked as well for me.

I'm very pleased with using this stuff as a wear layer. I'm not as pleased for patching but, hey, it gets me back on the water.

Ken

[Jim P]

The ocoee is still holding up well. It has taken a couple of good hits and even a good gouge from some rebar. None of the glass sheet is peeling off yet...

I did use a chopped mat/slurry to repair the gouges, that looks like it will not be lasting as long (I see one edge of the patch working loose).

Disclaimer - the Ocoee does not get out as much as she used to so she has only had about 15 good days on the river but all of them have been good testing days including low water cheat runs etc.

[yarnellboat]

Thanks for writing that up bambam!

So, it looks like my ABS slurry may not be a total disaster - it's hardened up.

The bad stuff I cut away was all air bubbles, probably too thick a layer, or too quick to add a next layer, or possibly too thin a slurry (i.e., too much acetone). Or, I had it in the sun, maybe that dries the outer "skin" too quickly? Hard to say, but something made for airy/spongey ABS.

The next attemt was all soft again, to the point of deforming/sagging the boat. I had the boat belly-up at that point, but flipping it open-side up seemed to help - maybe just not letting the slurry pool/sit on/in the foam is the trick?

Anyway, it hasn't been perfect or predictable, but maybe the nose isn't wrecked. I'll continue building up the ABS to give my bow back a solid canoe shape, and I think I will glass it, using traditional glass & epoxy resin.

I may just glass the inside (I'd use Kevlar if I had any), and see how the pure ABS holds up. First time I wish I hadn't tried getting fancy and using the slurry with the fibergalss cloth, that seems to have been the undoing of my earlier attempt, and I'd if I'd just left the ABS, it probably would've been fine. Or if I hadn't paddle at high speed into that rock.

PY.

[yarnellboat]

bambam,

Looks your "wear layer" of paper-thin paint-on ABS worked OK. Mine along the keel line wears off pretty easily. I find the ABS slurry is better for impact/sructure than it is for wear/abrasion.

I also have a thin ABS sheet on the inside of my hull (over a bunch of hairline cracks). I put it down with 3M urethane adhesive and it's worked very well. Several years in, a few spots along the edge have lifted a little bit, and I've just sealed them with Goop.

I wonder the same thing about your ABS-sheet patch over the slurry repair as I do with my use of glass & slurry... do you think it would've been better if we just left the cured ABS slurry alone and didn't bother trying to protect it with something fancier?

Pat.

[bambam]

...
I wonder the same thing about your ABS-sheet patch over the slurry repair as I do with my use of glass & slurry... do you think it would've been better if we just left the cured ABS slurry alone and didn't bother trying to protect it with something fancier?

Pat.

I wouldn't trust the ABS paint to have the strength to bridge a crack.

That red Ocoee is back on the sawhorses as it's leaking like a net. (And this time it's not just leaking from above!) Turns out the 1/16" thick patch has a crack in it as it didn't completely bond to the hull because there was a void between the patch and the hull.

More to come ...

Ken

[Jim P]

I only have a couple of pics from the rebuild and a couple as she stands today. As you can see the bottom has a few small black patches from impacts from rebar where it dug out a chunk of hull. You can also see a few deep creases in the hull.

There are no soft spots or areas peeling up from the original repair.

I still think this repair will go at least 60 days on the river - considering the cost of the repair its a lot less than a new boat.



http://www2.snapfish.com/thumbnailshare ... _94072992/

[yarnellboat]

I've continued building up the bow skid-plate area with the ABS slurry, but it's taking days to harden, and I'm concerned is made the insides permanently mushy in a few spots. Time will tell.

If I need to cut it all off, I may try a LePage marine epoxy that appears to be fairly flexible. Or I may just leave the ABS mostly hardened, ignore the bit of squish, and just glass over it anyway and see what happens.

Anyway, for whatever reasons, I'm not liking the feeling of working the ABS slurry this time round.

PY.