AD16 - Cool Change

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jacquesmm
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Post by jacquesmm »

Good to see the progress.

I don't precoat and therefore, do not have to sand the blush . . .
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ks8
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Post by ks8 »

Its good to hear someone can and is building during winter.

It snowed this morning. No epoxy til march for me.

Happy belt sanding!

Up here I'll be waiting for the *cool* to *change* to warm.

ks

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Post by llew »

Terry good luck from SA as well! Cannot wait for your pics.

Jacques, could not help notice you saying that you do not precoat and therefor don't have to sand the blush. Please tell us more, i.e. is it really ok not to precoat?
Llewellyn
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jacquesmm
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Post by jacquesmm »

llew wrote:Terry good luck from SA as well! Cannot wait for your pics.

Jacques, could not help notice you saying that you do not precoat and therefor don't have to sand the blush. Please tell us more, i.e. is it really ok not to precoat?
OK, let's make this clear: I precoat just before applying the fillet and the tape.
In other words, I assemble the hull with plywood that is not pre coated but I always "prime" where I apply fiberglass or putty.
I prime those areas maximum 24 hours before starting the fiberglass, usually 1 or 2 hours before.
What the builder proposed here was to coat all the panels flat on the floor, assemble the boat then sand and apply putty and fiberglass.
The problem with that method is that you have to sand the assembly before starting with the fillets or fiberglass.
There is no advantage to that, quite the opposite.

Bottom line: you must prime or precoat the plywood but do it just a few hours before the fiberglass, not days in advance.
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ArizonaBuilder
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Post by ArizonaBuilder »

Bottom line: you must prime or precoat the plywood but do it just a few hours before the fiberglass, not days in advance.
So when you FG the hull with cloth, is it fine to prime one night and lay cloth the next night with washing the blush or sanding. I don't think I could lay the cloth if the epoxy is still tacky or wet.
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ks8
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Post by ks8 »

When you actually get to the point of sheathing... (gee, we'll see more pictures by then I hope)...

Deems panels are so shiney... looks like dey need to be roughed up a bit. Shoulds I sen da fellas owt and hav em woik 'em ova faw ya?

lookin good...

JustRight

Fiberglass on tacky epoxy...wet on wet if you can

Post by JustRight »

I think you'll find that the you can lay the fiberglass on tacky epoxy and if you don't press it down hard, you can pull and rearrange just fine. When in place, apply pressure to set the fiberglass and recoat with flowcoat of resin. I have used a little one inch wallpaper seam roller to roll down the fiberglass. For larger coverings of glass, it helps to have an assistant. Also, it helps to have the glass precut to shape before you start. You won't have much time to trim fiberglass after it is rolled in place.

I can see how Jacques builds boats in half the time I do. By precoating or priming shortly before filleting , you will get a better bond with the epoxy. If you can follow up with taping the fillets [assumes you can fillet smoothly enough that no sanding is necessary], you can really get a lot accomplished in one session. Good idea.

The problem I had was in a larger boat, you have to have some help to get everything done in one session. Once you stop to let the epoxy harden to the point that you can sand, you will have to water wash, scrub, and sand before applying the next coat. I always worry about getting the bare wood wet. That's why I flowcoated, scrubbed and sanded the panels before assembly. I thinned the epoxy for the prime coat. There are now very thin epoxies available which saturate easily and some advertise no blushing. [MAS resins] Scrubbing and sanding on a flat panel is much easier than once in the hull. The flow coat raises the grain slightly and when sanded, give a very smooth surface for subsequent layers.

I tended to tack the joints together between the wires. After the epoxy hardened, I pulled the wires and completed the fillets. I never learned to fillet smoothly enough that I didn't have to sand the fillets. If you have rough spots in the fillets or in subsequent layers of fiberglass, the fiberglass won't lay straight and you can get air bubbles or pools of thick epoxy under the next layer. If you sand agressively after the glass has set, you run the risk of sanding through the glass [cutting the threads] and weakening the layup. I can trace one notable failure in my rudder to having sanded the glass. The fiberglass is an essential part of the composite construction. It must be treated with care when sanding.

It is all a matter of technique!

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Post by Steve_MA »

I am doing an FL14 and getting to the point of glassing the hull. I am planning to precoat the hull and is some cases wait until its not tacky anymore to apply cloth. With the E-poxy sold online here, I think its safe to do within 24hr or so.

I haven't found a need to sand to my fillets either .....before it sets hard you have alot of time to shape it. Also, I dont put the tape until it starts to set up, that way you arent likely to massively mis-shape your fillet when you add the tape. I ended up using a spoon to shape the fillet before tape, a 3" roller to press the tape into the fillet, and my fingers wet with epoxy to smooth make sure the fillet is smooth and shaped as desired.

I am no expert, but thats my plan/experience. Good luck.

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Post by jacquesmm »

ArizonaBuilder wrote: So when you FG the hull with cloth, is it fine to prime one night and lay cloth the next night with washing the blush or sanding. I don't think I could lay the cloth if the epoxy is still tacky or wet.
I apply the fiberglass on wet or tacky resin but you can wait at least 24 hours without the need for snading or washing.
That is a valid method for our Marinepoxy and SilverTip. Standard System Three is OK too up to 24 hours but not more. WEST and MAS MUST be sanded. I don't know about other resins but I would sand.
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Post by ArizonaBuilder »

I wonder if putting a piece of plastic down between the wet epoxy and cloth, so you can slowly remove the plastic while positioning the cloth, would work.

I am just thinking about when glassing the outside of the hull. Not sure it would work for the inside glassing.. Just another crazy thought.

Something like pulling the backing off of double sided tape while you are laying it down.. :doh:
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