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Fiberglass Layup

Posted by ozarkdrifter 
Fiberglass Layup
October 30, 2019 03:30PM
As I await delivery of products (ordered but slow going), I'm pondering layup. I have 10oz fabric (50" wide) and 6oz tape (6" wide). I had planned for 2 layers inside for bottom and sides, 2 layers outside for side panels, and 4 layers on the bottom. I also plan to coat the bottom with wetlander bottom coating....which I understand bottom coating discussion is it's own very large topic. As I've stated before, 90% of the boat's life will be spent in Class I-II water, though I suppose if I'm building a boat that can row Class III-IV it might as well not just look the part. 10" rocker at the transom and 3/8" sides. Too much glass? Overkill? (that one's obvious, but still worth hearing about) Hope all is well, can't wait to get started!

Brad
Re: Fiberglass Layup
October 30, 2019 04:27PM
That's a manly layup. I like it. The only thing I'd change would be to use one layer 10oz on the outside side panel instead of two. I have a 12 year old boat I made with 1/4" inch Meranti Hydrotech side panels, which I glassed with one layer only, with 3.5oz fabric.

I did put a small hole through the side once, which I obviously fixed. I tried to goose the boat up onto a partially submerged trailer by twisting the throttle on my 20hp outboard. A huge gust of wind hit the front of the boat at just the last second and I rammed the sharp corner of the trailer.

Would 3/8" with two layers have survived? Maybe. I built my first boat in 1979. That's the only hole I ever (ever) put in a boat. In all that time. I have never used more than one layer on an outside side panel........although usually 10oz rather than the 3.5oz mentioned above.

I do use 2 layers on the outside (and inside) side panel when making an all Plascore boat. But not with plywood.
Re: Fiberglass Layup
October 30, 2019 05:46PM
Excellent advice thank you. I'd kinda figured that schedule was in the "stout" category but thought there may be some overkill built in there somewhere. Nice to know you haven't poked too many holes in too many boats for all the water miles you've logged out west. Stands to reason I could probably float my docile rivers with far less a boat. Maybe boat number two I'll see how light a boat I can make! Thanks again Sandy.

Brad
Re: Fiberglass Layup
November 28, 2019 12:45AM
If I wanted to regularly slide it of the trailer and scoot it accross the gravel trail and down the bank instead of using the ramp (like they do on youtube) what would the bottom layup be? I was thinking a combination up to about 15 oz and carbon fiber/graphite on the most outside layer.
Overkill?
Re: Fiberglass Layup
November 28, 2019 01:40AM
Carbon fiber is expensive. It makes a stiff but brittle layup.

For durability Kevlar would be better. Or Polypropelene. Forgot the trade name. Or maybe just lots of glass.

Kevlar is expensive too. It doesn't break but when you sledge hammer smack a rock the resin surrounding the Kevlar weave shatters. The usual way to fix that (with glass) is to grind the soft spot out and patch in carefully cut-to-fit glass patches. Then cover with a bigger patch.

You can do that with Kevlar too but the grinding is difficult. Most regular discs just turn the Kevlar into a fuzz ball. Expensive grinding disks will do it to it. Just beware.
Re: Fiberglass Layup
November 29, 2019 01:42AM
Then Dynel sounds like the better choice in rocks. I hear it is also more form fitting and forgiving than glass.
Re: Fiberglass Layup
November 29, 2019 01:52AM
So for a Drag&Scratch boat what would the layup be for glass and also for Dynel.

I could be wrong, not having ever used it, but I think I heard that Dynel is also slightly more flexible and forgiving against abuse.

What might be the layup?
Re: Fiberglass Layup
November 29, 2019 12:26PM
Dynel does sound like good stuff. Someone on this forum sent me a sample of dynel 20 years ago. I still have it. I should have tested it a million times by now but............I didn't. It's still in the 8x10 yellow manilla envelope they sent it in, in a shop drawer with all my tool parts diagrams, which I don't really need anymore because all that stuff is online now.

Aramid is, I think, a generic trade name for polypropelene fabric. Back in the 80s there was a guy--a retired chemical engineer--selling a line of epoxy resins with the trade name Tech-On. He also sold polypropelene fabric, which I think is the same as Aramid. It was amazing stuff.

Some people say, about polypropelene fabric, that it uses too much resin for a hand layup, and that it has to be vacuum bagged. I did some hand layups with it and they were fantastic. He went out of business and I've never succeeded in finding a new supply. I haven't really looked in a long time too.

Polypropelene fabric (Aramid, I think) is flexible. You can wet it out with resin and let it cure. And then bend it like rubber and it doesn't break. That makes it perfect for a coating layer over plywood, where you get the stiffness from the plywood. And space age abrasion and impact durability from the coating.
Re: Fiberglass Layup
November 30, 2019 01:14AM
I'm pretty sure that Dynel is Polypropeline like Aramid. Anyway Ruell Parker used to use it almost exclusively to cover his sharpies. He used oodles of it. page through his books. he was quite an innovator and live down near Raka.

Re: Fiberglass Layup
December 03, 2019 03:53PM
How is the build Brad? I hope you're finding quality time to work on it.
Re: Fiberglass Layup
December 03, 2019 10:37PM
My brother picked up lumber from the shop last week, which other than "extras" concludes my procurement of supplies. I bought it all.....now I just have to build the thing. Time has been fleeting, and we're shooting for a start date around Christmas. I have some time off next week.....but plan to be fishing - shouldn't let a boat build get in the way of why I want to build the thing right? I'm ready to get started, prepare for the onslaught of pictures and questions in a few weeks! Happy Holidays!!
Re: Fiberglass Layup
December 04, 2019 02:07PM
Oh, we'll be watching, lol. I wish I were building another.
Having this one complete I now have time to examine what features the next one will include. The next one will likely be a 17 footer or a power drifter.

Best Wishes!
Re: Fiberglass Layup
December 10, 2019 05:52AM
I like Parker's boats, but I think he got it all wrong on Dynel. Dynel is great for abrasion, which is what sliding over rocks is all about. But structurally it is flexible. Wood is not flexible in the thicknesses we use in boats. Or at least not so flexible it requires Dynel. Think of glass fishing rods, or bow limbs. Glass bends enough but will share the load with wood. Glass is very similar to wood and works beautifully with it. Dynel is a coating, but does not carry loads, unless you use ridiculous amounts of it. There is a reason why there isn't Dynel chine tape, or at least it isn't popular. OK, linear dynel fibers.:) Exept to make the fabric itself.


Carbon is the reverse problem, depending on how you use it, it will often carry all the loads, then it breaks, creating a stress riser in the underlying wood, so it may break also. Getting carbon to play with wood is tricky. It took quite a long time for people to get carbon to play well. The WEST guys, for example figured out that when making their spars, they had to put it only on the inside of the wood, or the carbon would take all the load. That might be ok if you have the budget, and aren't putting the carbon over some heavy wood structure where you have basically spent a fortune on light boat materials, but ended up with the weight of two boats. Carbon is totally awesome in the right place, and the WEST guys liked it with wood, but it has to be used systematically.

What people tend to do is think "well this thing specifies 6oz glass, it will be a lot stronger if I use 6 oz carbon. But if 6 oz carbon is not strong enough to carry all the loads, you will end up with sequential failures, in the worst case. I have made that mistake, and heard the bang.

The way to think of Dynel is say you have a rope you think is a little weak, if you pair it with an elastic band will it be stronger? No the elastic will not pick up any load until the rope fails. Same question with a matching piece of music wire? No the wire will take all the load until it is overwhelmed, then you hope the rope is actually strong enough. That is how carbon plays.

Dynel could be perfect for a drift boat if the glass laminate schedule on the chines was tough enough, and the dynel was used where extra protection was necessary. The dynel will be great on abrasion, but if you take a major global hit, like a canoe falling off a float plane... The Dynel is not coming to that party.

Another few things about Dynel being easier to use:

1) it is much thicker than similar weight glass which can be good. If you were planing on using 2 layers of glass mainly for abrasion resistance, then one layer of Dynel might do. But you need to watch your resin weight budget;

2) Dynel is less dense, so it will float up in your resin, which can be awkward. today people say vac bag it, which is unnecessary, and not necessarily helpful if what you want is abrasion resistance. But if you love that kind of thing, it will press the dynel down and ensure a compacted laminate;

3) It can fuzz up, which can be awkward, but it is the kind of behavior that is typical of abrasion resistant materials.

-----------------------------------------

Kevlar is an aramid. As is Nomex.
Re: Fiberglass Layup
December 10, 2019 12:50PM
Take this one step further ThomD.......Is the carbon fiber facts above comparable to the habits of kevlar? I've often wondered why it is only used for heavily braided areas (skids). I've not seen it used for total glassing of boat hulls.
Re: Fiberglass Layup
December 10, 2019 01:00PM
Awesome analogy:


"The way to think of Dynel is say you have a rope you think is a little weak, if you pair it with an elastic band will it be stronger? No the elastic will not pick up any load until the rope fails. Same question with a matching piece of music wire? No the wire will take all the load until it is overwhelmed, then you hope the rope is actually strong enough. That is how carbon plays. "

According to your info then I think that Dynel is more appropriate for large, standard budgeted, modest performance and larger paneled projects where there are few if any point loads such as rock hits.........for example Parker's big sharpies???
Re: Fiberglass Layup
January 20, 2020 03:06PM
Boat work has begun!! The side panels are cut, dished, and interior glassed and flow-coated. I'm preparing to attach the side panels to the formers and begin the shaping/straightening process. I'm using plascore for the bottom panel, and plan to pre-glass the interior side. I'm wondering, is it possible to apply BOTH (two) layers of glass in the pre-construction phase? Or is it best to only apply one, then apply the second after the bottom panel has been attached. Plascore seems pretty pliable, so hoping I could apply both in pre-construction, leaving only chine edge taping over the fillets. Thoughts appreciated and pics to come after this weekend.

Brad
Re: Fiberglass Layup
January 20, 2020 08:37PM
I have only ever done one pre-glass layer. So.......I can't say from experience.


I have preglassed both inside and out. I prefer to do the inside.

Best answer I can give.
Re: Fiberglass Layup
January 21, 2020 06:36PM
Understood. Everything is a first time for me, but if it's a first time for you it's probably best left to braver souls. I have a saying at work: if you're the only person doing it that way you might be a pioneer, but you're probably a moron. A bit hyperbolic but there's some wisdom in it somewhere I'm sure. Will send out some pictures after the weekends work is concluded. Might even resemble a boat by then.
Re: Fiberglass Layup
January 21, 2020 09:11PM
I been a moron many times. Deja Vu all over again
Re: Fiberglass Layup
January 22, 2020 07:49PM
Secondary question. When applying the stem, resin plus screws - using a simple triangle shape. Must the screws be removed from the stem and the holes filled with resin before glassing? Or considering the entire stem, in and out, will be glassed just leave them in place? Nitpicking, but betting you've tried both ways.....
Re: Fiberglass Layup
January 22, 2020 11:50PM
When I screw or bolt down anything removable I heat the screw and wax it, and then drive it down into a hole filled with resin. The screws tacking side panel to stem don't really need to be there after the glue is set. Screws you might need to someday back out can have the driver slots filled with wax, so you can dig them out eventually. But I haven't at stem.
Re: Fiberglass Layup
January 23, 2020 11:58AM
That was somewhat incoherent above. I'm phone poking. From Gulf Coast. Where the snow conditions are ideal right now.
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