I think I may have a source. Let me
look for the link. Back later.
Inside is link to possible source of
Wallbridge “Boatbuilders Manual.”
http://www.eagerplastics.com/bookboatbuilder.htm
I have NOT tried them, but the price is more than fair, so contact them and see if they come across.
Haven’t heard of that new material. I have a Spheretex reinforced boat. Spheretex is FG cloth puffed up with tiny bubbles, so after resin impregnation, the layer is lighter than it would be, and stiffer because of thickness. Don’t know about strength, but whitewater boat builders use it.
link
It appears to have shown up in the last few years as a lower cost replacement for carbon in wind turbine blades but also ballistic use in vehicles/ships. From what I can gather it seems to have more elasticity/fatique resistance than regular glass or S-glass. Weird, like tough weave but all glass?
http://www.pressreleasefinder.com/item.asp?id=11865
Compared to E-glass, HiPer-tex™ glass fibre delivers overall superior performance: 30 percent higher strength; 17 percent higher stiffness; 45 percent higher strain energy; 10 times greater fatigue resistance and 30 percent lower coefficient of linear thermal expansion. HiPer-tex™ glass fibre delivers these benefits in ballistic applications that meet the following standards: FB4, STANAG 4569 Level 2 and STANAG 4569 Level 4.
thanks for link below
that’s the book that got me to make up bunches of 4mm plywood test panels and discover how different s-glass is from e-glass.
When they say ballistic applications,
do they mean as in composite armor?
glass vs. kevlar
I’ve had both glass and kevlar kayaks.
The kevlar weave looks kind of like wicker, if that makes sense, and the glass cloth is more like cotton, so the glass cloth soaks up the resin a little better.
In my experience the kevalar lay (the ultra light) would have a higher chance of some minor gel coat issues, but your probably not going to have any issues with it.
I would say get the one you can pick up and transport.
That’s what I did. My Valley is 10 pounds lighter than an NDK, and there is no way in hell I need that extra ten pounds to get up on the roof racks.
no idea
yes, vehicle armor (n/m)
Kevlar
There are two completely different kinds of Kevlar, one’s structural (which is what we are discussing here) the other is balistic, not composite cloth that’s sewn as a fabric. The stuff used for armor is not the same thing as the stuff used for boats.
Bill H.
Yeah, that was why I asked about the
ballistics issue. Some cloths will perform very well for stopping missiles but not as well for running into rocks.
squirt boats
Might want to do a web search for squirt boats and look at their layups. They are all composite boats only used in whitewater and the closer to the rocks the better.
Bill H.
glass on kevlar
if i had a kevlar boat and put a hole in it on the rocks, could I sand it down and fix it with a fiberglass cloth?
SUre, but
The issue is that a laminated hull is an entity that works together regardless of materials. Patching ~ flexible Kev with ~stiff glass is going to cause a scab like area that is less flexible than the rest of the hull. So we know where the stress risers and the next break will be.
Of course any patch causes a stiffer scab.
The types of Kevlar are 49, used in structural stuff and 29 which is treated and functions unresinated in projectile proof vests.
Sometimes, a well planned patch can
stiffen a stress area, such as a chine, and move stress zones to areas nearby that are less likely to be bent beyond their limits.
I’m becoming more and more aware of issues about how the edges of a patch should be tapered, shaped, and located in order to avoid recurrence.
Fortunately, many breaks on composite whitewater boats are semi-randomly distributed, and further breakage does not occur. The most troublesome area is the stern, in the center and/or the chines, because of the hammering that occurs when going over a sharp ledge.
cloth is cloth
conversely I do not understand why is Kevlar fix more complicated. Kevlar is a cloth like Fiberglass - in general you sand the area, lay the cloth, wet it with epoxy, sand, repeat epoxy, sand, repeat epoxy, sand, gelcoat, sand, gelcoat … until the thickness matches the rest of the boat.
No, actually that is NOT the way it goes
– Last Updated: Dec-09-09 5:00 PM EST –
and often Kevlar is the wrong cloth to use for exterior patches. First, it does not have compression strength equal to S-glass or even E-glass. Second, it is a little harder to cut Kevlar patches, and harder to wet them out. Third, a serious patch involves at least 3 concentric layers. I put the largest on first, Charlie prefers the other way around. Fourth, why all the extra epoxy applications? Just to fill the weave? Use UV resistant spar varnish instead. Finally, if a Kevlar patch is in a wear area, it will fuzz. Glass patches don't fuzz.
Usually, Kevlar patches should be reserved for inside the boat, where they resist tearing better than glass.
Not dumping on you..... There isn't much good info on patching. Many "pros" do it improperly.
no problem.
no worries. I have minor experience with fiberglass but when I saw the kevlar and carbon cloths I thought to my self there was not much difference but I defer to your experience. Thanks for answering. I was looking for a competent answer.
sanding
Can’t sand Kevlar, turns into fuzz. One of the downsides to Kevlar.
Bill H.
I used a propane torch on the fuzzy
underside of a Kevlar kayak. That made it easier to remove the fuzz, partly turned to little nubbins, with a scraper. But this method won’t help when sanding a Kevlar patch.
But then, why would one use a Kevlar patch on the outside of a boat? Would apply only if the break occured because of tension rather than compression. And for inside patches, it is seldom necessary to try for smooth edges on Kevlar patches.
Another trick
– Last Updated: Dec-13-09 10:07 AM EST –
Propane torches help, and are also useful for Creme Brulee. One can also trim Kevlar/Twaron fuzz with a razor after wetting it. 'Best to have more than one razor.
I agree, kev patches belong on hull interiors. Peel ply is by far the best way to smooth the edges.
There are hulls out there with Kev/Twar as outer layers. After starting with a poor choice, the outer patches probably need to match, a poor solution.
In that unhappy case, I'd patch using peel ply, then paint with resin. The patch will always be proud. The hull will always want to turn left or right, depending on the location of the proud spot.