We have a couple of days rain here so i thought i would stick my tent [.5oz material] out again ,see what happens. Lots of condensation this morning and some drops on the inside, so to distinguish between condensation and possible leaks i cleaned off the haze and left it for a while. I have a few leaks, which i will attribute to some errors in constuction,[ use of stickum and marking pens] which resulted in some heavy rubbing of some areas. In the photos below inside drops appear bright around the edges. However! all other areas are leak free after 24 hrs in the rain, there were no drips, instead all drops ran down to the edges. This material has been folded stuffed many times,



this is a shot of the leak free area;


Now an interesting discovery, i happen to be waterproofing the new skin of my ultralight kayak using Proform urethane clearcoat. As an experiment i brushed some on a piece of lightest cuben, heat dried it, seems to be a perfect match, cant't scape it off or wrinkle it off. Hmmm.

"i happen to be waterproofing the new skin of my ultralight kayak"

I'd like to talk to you about this, because I happen to be building a Baidarka right now (with Corey Freedman from Spirit Lines and Skinboat.org)

Tyson, fire away , though i might not be the best person to talk to as i am an experimeter, I end up with a boat for the very brave, although it suits my very modest kayaking ambitions.
Like i say i am using an automotive 2 part urethane clearcoat [Proform ,CDN, i think] have used their stuff on my car projects always with great success. Last year i tried multiple thin coats, this time its 3 heavy ones ,working great. For the bottom of the hull i found that Lepage polyurethane window sealant dissolved in acetone works great, tough as hell [ i test by rubbing a piece against a pointy rock].
I'm using 7oz polyester from Dyson's by the way, i suspect the nylon is tougher ,i poked a hole in it last year with just the clearcoat on the bottom, hence the Lepage this time. I also found it expands a bit then wet.

You guys have any recommendations for water-based urethanes?

Thanks for the Photos Ziff. We need to see more real world tests like this. Instrument testing is fine, but there needs to be a real world derivation for it to be meaningful. The Cuben that I am putting through crumple tests looks like yours and is doing fine also, although it is more a pack weight.

Dan,

You have been playing with cuben for years, but have not brought anything to market. Is it just educational or do you see something you might use? I have some cuben gear, but do not have a lot confidence it its durability, and use it carefully. As a tarp, it was worked well.

Hi guys. I build canoes and was also thinking about a skin on frame boat. However, I rejected the Cuben material because neither varnish nor epoxy really sticks to it. As I understand it, it is primarily a HDPE materieal reinforced internally with PET fibers(dynema.) Neither of which bonds all that well with the plastics.

It's just a matter of time. I was too brutal on it in my first tests years ago. I'm fascinated by the fabric, and, as many people know, it makes pretty amazing tarps. There are still misunderstandings about it, which have led to this controversy. I look forward to whatever applications I will use it for. One of the biggest barriers for me has been learning to speak Cuben. I hated taking foreign languages in school!

Edited by wildlife on 04/05/2011 17:36:39 MDT.

I'll be using ballistic nylon, with a urethane coating, for my Baidarka... What wood(s) are you building your canoes with?

Tyson, my boat is carbon fiber tubes, as i say very experimental. I wanted something to pack into lakes and i wanted to see if weight would trump drag [ it didn't very much] as once on a trip someone with a very lightly packed boat was able to go like stink. One of the top spares snapped last year when i was practicing a paddle float rescue, it had all my weight plus the leverage of the paddle across it, BANG! So i reskinned it this winter , adding a reinforced filament wound tube at the break.
Dan,James , i think a rowing cat , something like the fishing ones could be made with bubblewrap/cuben floats, carbon frame. easy to carry, more stable than a kayak. Lots of $ though.

the way the tent has been outside in the rainnow for 2 days lots of rain off and on. After a certain point waterproof is just waterproof and further testing is pointless.

made you look...haha

So Dan when are you going to make a cuben pack?

Edited by Mountainfitter on 04/06/2011 20:11:41 MDT.

Who said anything about packs? HaHa. That reminds me though, I think I'll dig a couple out and see what they weigh. It was so long ago it seems.

Edited by wildlife on 04/06/2011 21:24:58 MDT.

Hey Dan,

You may want to check out this.

Call Corey and talk to him.

Cheers.

are beautifull boats, i'm too much a weight weeny.

"i'm too much a weight weeny."

Sure, but for sea kayaking... it doesn't get much lighter than these! These babies are ocean worthy! I can't wait until mine is done... I've only completed the bow, stern, and gunnels...

James, I considered a cuben skin boat, also, but abandoned the idea a couple of years ago when evidence began to accumulate that the material has a pinhole problem. It's actually PE (UHMWPE) fibers between sheets of PET film, and polyester film fatigues with flexion. If you cut a piece out of a polyester water bottle, fold it, and flex it repeatedly along the fold, it will turn white and eventually fail at points along the fold. Not all plastics do this. This is the reason, I think, that Richard Nisley has observed leakage through aged (creased) cuben samples.

We can see in Richard's micrographs that the cuben reinforcement layer is full of bubbles between the fibers. At these points there is no interlaminar adhesive, only a tiny air space between the two sheets of film. After some crumpling, each sheet of film gets riddled with tiny fissures, and I think leaks occur when two pinholes occur over the same interlaminar air bubble.

These pinholes are too small to be important for shelters, in my opinion. I agree with those who have said that real-world performance matters more than hydrostatic head in this case. For shelter materials, since condensation usually occurs anyway, a small amount of leakage in no way compromises the function of the shelter. But we're never going to see a successful cuben packraft, canoe, kayak, or inflatable sleeping pad, I'm afraid.

"These pinholes are too small to be important for shelters, in my opinion. I agree with those who have said that real-world performance matters more than hydrostatic head in this case. For shelter materials, since condensation usually occurs anyway, a small amount of leakage in no way compromises the function of the shelter. But we're never going to see a successful cuben packraft, canoe, kayak, or inflatable sleeping pad, I'm afraid."

I feel the same way.

What are you using for your skin? Also, what is your frame material? I'm always interested to see different designs/ideas, regarding SOF boats...

Thanks for that lead Tyson, it's much appreciated.

Maybe Cuben isn't appropriate for floors?

Tyson, I actually never got very far along in that project. I originally had a plan to use wrapped s-glass composite tubing for the frame and cuben skin, and I modified that to coated nylon skin, but all of that, and many other things, fell by the wayside when I went to grad school.