# Filler/adhesive question...



## Robtattoo (May 10, 2018)

Hi folks, first post here so please forgive me if I'm repeating a common question.

I'm rebuilding an old '87 gheenoe Classic & I have a pretty specific question. I've ground out the old, wooden, half height transom to be replaced with 2 layers of ½" coosa. My plan is to make the transom up to full depth with several CSM/1708 laminations over & between the 2 boards.
However, the outer hull skin is very uneven. Possibly as much as 1/8" variances. When I clamp my first board to it, there are obvious voids.

In my mind, I 'should' be able to mix up some blend of fillers with my poly resin that I can then apply in a thick layer to the outer skin, clamp the new inner plate in place & the putty will act as a void filling adhesive.

Is this even possible? If it is, what filler products would I need? One place is telling me that wood flour makes an excellent, thick adhesive, another recommends silica, several suggest blending milled fiber or ¼ strands with another thickener..... It's so dang confusing!!

This is my first ever time with glass work & I've been googling my face off for months, causing more & more confusion!


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## yobata (Jul 14, 2015)

You should only use the wood flour if you are using epoxy. For the polyester resin that you mentioned, I would use silica/microballoons


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## Guest (May 10, 2018)

What Yobata said


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## Robtattoo (May 10, 2018)

So basically, what I want to do is possible, I just need the correct fillers. Right?

Do I need the phenolic microbaloons or glass bubbles? I'm looking on www.fiberglasssupplydepot.com

How do I know what ratio of cabosil/microbaloons I'll need?


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## yobata (Jul 14, 2015)

Robtattoo said:


> So basically, what I want to do is possible, I just need the correct fillers. Right?
> 
> Do I need the phenolic microbaloons or glass bubbles? I'm looking on www.fiberglasssupplydepot.com
> 
> How do I know what ratio of cabosil/microbaloons I'll need?


I think it's up to you which to choose from (I'd stay clear of the talc powder). For the ratio, I have always just added some, mixed it in, checked for the consistency, add a bit more if needed... you are looking for a "peanut butter" consistency


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## Guest (May 11, 2018)

If an 1/8th gap is all, you can also bed and clamp in 3-4 layers wet out csm. The clamping will move and “squish” the wet mat around a little and should fill the void. I’ve had good luck doing this.


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## Guest (May 11, 2018)

I use aluminum channel across the back of transom and have custom built transom clamps so I can clamp the heck out of the core while keeping transom straight. If it’s a rounded transom you’ll have to improvise your clamping technique.


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## DuckNut (Apr 3, 2009)

Frankly speaking 1/8" on a Gheenoe is pretty good and can be left alone, after all it is the transom.

But if it you bothers you that much use 2 pieces of 3/4" marine ply. Put one on each side and screw right through the transom and use the wood as clamps to straighten the wave. EDIT: Clamping the new transom pieces in place between the boards.

You can use screws like above or you can make some clamps like this









If you make the clamps you will need additional stiffeners or you will put another wave in it because it is so thin.


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## Guest (May 14, 2018)

You won’t need the 1708 between layers of coosa. I’d bond the two pieces on a bench. Set one piece on bench, add a layer of 11/2csm, place second layer on top of csm, and add weight or clamp together. After it cures, trim to fit. Save the 1708 for the outter skin of transom.


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## No Bait / Lures Only (Apr 10, 2011)

DuckNut said:


> Frankly speaking 1/8" on a Gheenoe is pretty good and can be left alone, after all it is the transom.
> 
> But if it you bothers you that much use 2 pieces of 3/4" marine ply. Put one on each side and screw right through the transom and use the wood as clamps to straighten the wave. EDIT: Clamping the new transom pieces in place between the boards.
> 
> ...


Nice clamps


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## DuckNut (Apr 3, 2009)

If it were mine I would use the screw method.
Starting from the outside:
3/4 ply; hull; slurry; transom piece; 3/4 ply

I would use deck screws and screw right through all of it clamping everything together. Keep in mind that you will need to cover the ply with plastic so the squeezed out slurry wont stick it in place. 

Cover the inside with glass and fill the holes after removing the ply's.


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## Robtattoo (May 10, 2018)

Thanks for the tips guys! It seems like the uneven surface is less of a worry than I thought. I do have a bunch of 12" throat clamps so with an inch of coosa, it'll pull it straight enough.
I've just got a little last-minute-anal-retentive sanding bits to do & hopefully I'll start making templates & laying up tomorrow. Wish me luck! (I don't know why, but I'm way more nervous about putting stuff in than I was about hacking stuff out!)


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## Guest (May 15, 2018)

Now is when all the prep or lack of will show. We all get that way, soinds like you did your homework so you should be fine.


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## Robtattoo (May 10, 2018)

So my next question/worry......

Can someone give me any tips regarding laying up in humidity?
I'm in middle TN & right now the daytime temps are in the mid-high 80s, but humidity is hanging around 70-80%

Do I need to increase my MEK: resin ratio to combat the humidity, or should I wait until the actual hottest part of the day, so the humidity is at it's lowest?
Or is this one of those things I'm horribly overthinking?

I really don't want to have to deal with an unset, gooey mess that just won't harden properly.


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## Guest (May 16, 2018)

If you have a dry place to work just lay it up. Catalize according to the ambient temp and allow to cure a day before removing clamps. Do not attempt to layup in the sun light or you will regret it. Humidity does play a role in the cure but if catalized properly it will kick/harden. If those of us in Florida waited for humidity to be low we would never get anything accomplished.


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## Robtattoo (May 10, 2018)

I finally dipped a toe....
I cut my 2 sections of Coosa to match the transom shape & layed up a layer of 1½oz csm on each. 
I'm going to trim & add a second layer between the mating surfaces tomorrow with a final layer on the inner piece for added stiffness & hopefully I should have the whole thing ready to fix to the hull tomorrow night!


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## Guest (May 17, 2018)

Agitate the csm skin with 80 grit before bonding. You can bond your two boards together and after a couple hrs bond them to the hull. You can skip the extra csm skin on the board. Did you decide how your gonna bond the core?


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## Robtattoo (May 10, 2018)

Wow, I didn't realise I could work it that quickly. Thanks for the tip! Will it still bond ok with just resin?

I'm going to make a putty with silica & milled glass & clamp everything tight. It'll be a week before I can do any more than that right now (fishing trip), but I'm planning on overlaying the whole inside of the transom with a layer of 1708, cut so that I can get a good 6" of bond against the bottom & sides of the hull.


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## Robtattoo (May 10, 2018)

Another quick question....
What's the best way of trimming the excess cured glass from around my edges?


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## Guest (May 17, 2018)

I like to put a layer of csm between cores when doubling. I place outboard core on table, 1layer cam, inboard core the weigh or vaccuum bag. After it kicks and cures for a couple hrs I then trim to fit as 1 piece and bond/clamp to hull. A couple hrs later I pull clamps and fillet edges then glass in. If you are carefull with clamp placement you can do your fillets while waiting on bonding putty to kick.


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## Guest (May 17, 2018)

As far as trimming, I use a die grinder with cut wheel to do most trimming. Then a 36 grit 2-3” roloc disk to finish that sorr of trimming.


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## yobata (Jul 14, 2015)

you can also trim the excess with a utility knife after the resin is cured, but since you may need to sand anyway, just use the sander/grinder...


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## DuckNut (Apr 3, 2009)

You need to cut the excess glass that is overhanging with scissors. The white stuff not the stuff that has resin on it. Then use your grinder to clean it up.

If the virgin glass gets caught on the disk you may get into a dangerous situation.


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## Robtattoo (May 10, 2018)

Got both pieces trimmed up & roughed up with 80grit.
I wet out both sides with resin & I've got them clamped together right now.

Once it's cured, I'll try dry clamping to the transom, just to see if it's stiff enough to pull the hull in flat. If it does, I'll bond it. If not I may add a skin of 1708 (I know it's probably belt & braces, but it's easier to buy more biax that to have to chop it out & start again)

Wish I had more clamps.....


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## Robtattoo (May 10, 2018)

Got a little further today.
Stringers & bulkhead cut, laminated & installed & I also decided I'd build a storage box under the rear deck.


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## Guest (Jun 7, 2018)

Nice


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## DuckNut (Apr 3, 2009)

See how much headway you can make when you stop overthinking things


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## Robtattoo (May 10, 2018)

Cut the ¼" ply template for my center deck this morning. Also cut & bonded my drain tube/deck support. If it doesn't heat up too much this afternoon, I'm hoping to have the Nidacore cut for the center floor & possibly get my first layer of CSM bonded to the underside. It'd be nice to get it all layed up & bonded in this weekend.

Yesterday I finished glassing in the rear bulkhead, stringers & storage, plus cleaned up all the splashes, blobs & resin overspill from the bilge & faired all the visible joints.


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## Robtattoo (May 10, 2018)

I've made a BUNCH more progress since I last posted anything constructive!
Rather than trying to upload a ton of pics, here's a link to my Facebook photo album, detailing the build......

https://www.facebook.com/media/set/?set=a.10155351012815978.1073741834.647060977&type=1&l=db8ed63036

So far, I've got all my rear deck supports in, rear storage built & sealed, rear deck cut, center floor cut, glassed & installed, grab bar mounted, front bulkheads & stringers cut & the front deck roughly patterned. Can't do any more glass work now until I get a supply shipment in!


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