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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!
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