One more time with reglassing our deck.

[44'cruisingcat]

I'd say both. Lighter glass would be a bit easier, easier to wet out, easier to bend around any curvy bits, more manageable epoxy batches.

And at the end, you have more glass.

The difference wouldn't be like night and day though.

[44'cruisingcat]

Probably just confusing things with more options.

[GILow]

Originally Posted by 44'cruisingcat

Probably just confusing things with more options.

Options are good though.

Just reading up on what you suggest now. Interesting, probably add a bit to the overall cost of the job, but not prohibitively.

My chief concern is working out if I can work with the added "complexity". One of those thought experiments best done while standing on the deck of the boat I suspect.

[Stumble]

Originally Posted by GILow

Greg, I believe TPRDA is not the same as an acetone based thinner. if you look at the MSDS for it, it's mostly acetone I won't try to upsell a product I have never used, but I have read a lot about it from people using it (not selling it) and to date I have not found evidence of problems.there are still people who suggest using thinners at all...

I have heard plenty of credible criticism of acetone based thinners used in epoxy. Again, I cannot tell, from my layperson perspective, whether those criticisms are reasonable or not, but certainly the descriptions that go to the molecular level do leave me thinking acetone thinning is counter productive. Third party laboratory testing proves thinning epoxy is counter productive

I do like the idea of something that penetrates the timber more, there really aren't any. Even superthin penetrating epoxy penetrates less than 1mm. Depth of penetration is simply never been shown to be important in wood encapsulation. The important bit it the water vapor barrier. I can see the benefit, and in our relatively benign climate I don't anticipate major problems with moisture. The boat spent the first 30 years of its life North of the tropic of Capricorn and South of the equator, then the next ten years closer to latitude 38S before coming here to Adelaide at latitude 34S so it has seen a variety of rainfall and temperatures. Despite this the design is such that it sheds water well, and it rarely, if ever, sees water over the bow.

Matt

I had never heard of this stuff so I had to look it up... it's just yet another snake oil attempting to pass off acetone thinner epoxy as something desirable.

Fundamentally epoxy is a structural material, and thus any formulator that doesn't publish easily available 3rd party testing data is either 1) hiding something, or 2) so cheap they can't be trusted. Failing to provide structural data would be exactly the same as a metal fan shop telling you 'sure I'll build the best chainplates you have ever seen, but I can't tell you what alloy of metal I am using, but trust us it's the best!'

It raises so many red flags it isn't worth continuing the conversation.

Epoxy sealing wood is a fantastic way to preserve a boat, doing it with thinned epoxy is just a waste of labor and materials. You might as well just go strait to the fiberglass.

[guyrj33]

you might consider Dynel in place of fiberglass. It is a woven product that conforms easily to curves and is frequently use to cover wooden decks here in New England.
Resulting texture is similar to a canvas deck.

[Scout 30]

I wouldn't thin either. Rough up the plywood with 40 grit. Use a good quality 3-1 laminating epoxy and wet the wood out before you lay the glass. Be sure to mix well. When it's done cover with Kiwi Grip.

[Cadence]

From your post, the old glass is lifting and leaking. My concern would dry rot in the plywood which may not be obvious Best of luck.

[Bluebeard]

I'm afraid I'm with Cadence,
My concern would be rot possibly, be almost certainly wet plywood under your lifting existing laminate. If it is wet, getting it dry could be interesting.
Tenting and a de-humidifier is the obvious answer, but a with certain amount of care with fire hazards.
Many years ago I used an SP systems resin that they call Eposeal 300. It IS solvent based, but is specifically designed for the initial coating with good penetration. SP are a serious manufacturer so I wouldn't question their products.
For a long time now I've only used cloth for any laminating, and I don't see why you would mix mat and cloth.
As to how you would actually lay it, you will be working down hand so it's relatively easy, but you will be limited to working in strips that are narrow enough to reach over. Personally use I would use 2 layers of cloth, with the top layer say 6 inches narrower than the bottom. I would set it up so that I could lay up one band across the deck within the time it takes for the resin to go off. Clean the presealed deck with acetone then paint it liberally with resin, lay you first layer of cloth, roll it in, the you will find that the second layer when you roll it will wet out without extra resin. As a non professional that is about the minimum resin density you will achieve.
If you are then able to lay another band, the lap will not have cured completely and the subsequent laminate will bond without problem.

When you have to stop, say overnight, then the 6 inch over lap will need to be cleaned with acetone to remove the bloom. I'm not convinced sanding is necessary but I probably would, because it costs you little. You may want to ask the experts, like West.

It's no big deal, just like paper mache wearing later gloves. ;-))

[Snowpetrel]

Id use a single lighter cloth, heavy cloth soaks a hell of a lot of epoxy and is hard to wet out.

In this case its just a waterproof layer, so it doesnt need to be super thick. Get your impact resistance from some sort of thick elastomeric non skid.

Ive had good success with botecote epoxy. No blushing and easy to mix plus npt so allergenic. Its thicker so much harder to get through the cloth. The TDRA stuff worked for me. Something like R180 epoxy is much better for glassing, but blushes pretty bad.

Worth having a play with peel ply. Its great stuff. Especially anything fiddly. Might not be worth it on your job, but its good stuff to understand. Kind of like a poor mans vacuum bag.

[GILow]

Originally Posted by Stumble

I had never heard of this stuff so I had to look it up... it's just yet another snake oil attempting to pass off acetone thinner epoxy as something desirable.

....It raises so many red flags it isn't worth continuing the conversation.

Greg, I am a bit shocked by this. Did you ACTUALLY view the MSDS or did you quote a web post which makes EXACTLY the same unsubstantiated claim. A claim that is subsequently, in the same post, explicitly denied by the distributors, along with an impassioned plea from the distributor to not propagate unsubstantiated internet facts.

If you did view the MSDS, can you please provide me a link to it, because clearly I am interested. I agree, from what I have read, that acetone thinning is not a good idea, but I am getting a totally different vibe about this product.

Here's the page I found which starts with the claim about acetone, actually, it does not start with it, but the Google summary puts it up there in the search results.

Bote-Cote epoxy [Archive] - The WoodenBoat Forum

Reading through to the end of the page finds the distributor emphatically stating that the product does NOT contain acetone.

Matt

[GILow]

Originally Posted by Snowpetrel

Id use a single lighter cloth, heavy cloth soaks a hell of a lot of epoxy and is hard to wet out.

In this case its just a waterproof layer, so it doesnt need to be super thick. Get your impact resistance from some sort of thick elastomeric non skid.

Ive had good success with botecote epoxy. No blushing and easy to mix plus npt so allergenic. Its thicker so much harder to get through the cloth. The TDRA stuff worked for me. Something like R180 epoxy is much better for glassing, but blushes pretty bad.

Worth having a play with peel ply. Its great stuff. Especially anything fiddly. Might not be worth it on your job, but its good stuff to understand. Kind of like a poor mans vacuum bag.

Ah, you are back from the cold bits then? :^)

So, it seems you are taking the same line as the boatcraft guys who advocated a single layer of 265 or 420?

I was going to use a non skid with a bit of boing, looking at Jim and Ann's recommended stuff among many.

I am still reading on the peel ply, jury is out as to whether I have the necessary coordination.

Matt

[GILow]

Originally Posted by Cadence

From your post, the old glass is lifting and leaking. My concern would dry rot in the plywood which may not be obvious Best of luck.

Ooh yeah, there's gonna be plenty of that to deal with, I am sure.

The good news is I have checked the lower layer very carefully (easy to do, we have exposed deck undersides) and found no problems, so hopefully any rot I find (and I will find some) will be in the top layer and therefore easy enough to rip out and replace.

But I love working with timber, so that bit of the job does not scare me, though maybe it should.

Matt

[UNCIVILIZED]

Minimum of 2 layers of glass, perhaps 3. This so that you can butt the seams/joints, in order to prevent high spots in the deck due to overlaps. And the multiple layers of cloth will completely cover any small gaps in these seam joints.
Also, you want a substantial thickness of glass. What happens when your grip on the outboard slips, & you drop it's skeg onto the deck from 1/2m up? Do you really think 1/2mm of glass can handle this, especially after a few million flex cycles.

You definitely want to ensure that the plywood's dry. Even if that means peeling the current layer, & adding heaters to the tent. As well as possibly using other methods along with to help to get rid of the H2O.
Drill multiple, small (3mm) test holes in suspect areas, & pinch the shavings that come out on the bit to test'em for moisture.

As to the thinning the epoxy thing. Skip it! No gains, all losses. And if you're really, really, really concerned with it's penetration. Hit the plywood with some super coarse paper on the grinder. It'll up the surface area available for the resin to bond to 5x.
Then when it's time to glass, first heat up the entire boat, inside & out, to well above ambient temp's. Deck's especially. And use warm, low viscosity resin. The heat'll help thin it out, thus aiding it's penetration.

PS: Peel ply rocks. Well, unless you like grinding fiberglass. So pass on avoidable misery here.

[Ramona]

On my fishing vessel I had to replace the fibreglassed deck. Fibreglass and csm over construction ply. I replaced with construction ply and 6 ounce fibreglass cloth with epoxy resin. The resin was the local FGI mixed 5:1. I simply started at one end and laid a small section at a time with easy manageable amounts of resin. Couple of inches of overlap. One layup straight over clean ply. This was followed by straight epoxy with clean builders sand sprinkled into the wet epoxy and over painted with oil based paving paint with more sand added. No bloom. The only advice I would give is to erect a sun shade and only work in the shade, much easier to see how the cloth is wetting out. Use plenty of resin too, it's cheap.

[GILow]

Originally Posted by Stumble

I had never heard of this stuff so I had to look it up... it's just yet another snake oil attempting to pass off acetone thinner epoxy as something desirable.

...

OK, it turns out the MSDS is NOT on the web. Not sure what you read, if anything, but for those that like to do REAL home work, here is the ACTUAL MSDS from the distributor.

For the record, I have no opinion one way or the other about thinning the first coat, this is something I will have to read a lot more about, from a range of DIVERSE opinions, before I make up my mind to what suits my situtation.

What I won't accept, however, are sweepings statements like those above based on nothing but quick and dirty google searches.

Matt