I am looking into Carbon fiber or Kevlar or the like to use to reinforce hull bottoms, superstructre and ribs. Can I get anyone who has any experience with some of these alternatives to fiberglass to chime in as to a few questions? 1) What type of cloth and resin you used, including weights, type of weave/ mat, type of resin, and any other particulars that may be useful. 2) What was it used for (even if it was for something other than combat ships), and why was it chosen for that specific application. 3) How it was to work with - How was it to apply, sand, repair, etc. 4) How did it work for said application, and to do over again, would you choose the same or different materials. 5) Anything else that might shed some light on these wonderful yet mysterious materials. 6) What the air speed velocity of a swallow is - African or European, dosen't matter.
I've used carbon fiber in one specific application, where it excelled. There is no good reason to use it anywhere where impact is likely as it will fracture under impact loads and the cost is not worth any benefits over fiberglass. think of it as a great stiffener but a bit brittle. both more stiff and more brittle than glass -In small hulls that become very flexible when the windows are cut and need some stiffening, a layer of unidirectional carbon fiber running port-starboard at strategic locations down the back side of ribs greatly stiffens the whole ship hull up. other than that, on larger ships I have never had a flexibility problem with glass think of aramid as a whole heck of a lot tougher than glass, and a bit stiffer I am using aramid fiber cloth rather than fiberglass on the bottom of a wood hull. if I were to do it over again, I probably would not, just from the PITA factor. Aramid fibers tend (in impact and when you try to cut them after the laminate is cured) to debond from the resin, when that happens, the resin flakes away leaving the fiber basically intact with shattered resin around it. this leads to fuzzball edges and an impossibility of sanding into the aramid layer if you need to shape the hull. the only reason I lightly sand into the aramid layer is to pull up the fuzz so that the next layer adheres better if I wait too long between layers and let the first fully cure as far as trimming, trimming after cure can be done but it is a degree of pain I would not willingly do again. best cuts I have gotten are with razor sharp chizzles and razor saws, any other method leaves the fuzz at the cut edge. you can go at the edge, if thick enough, with progressibely finer sand paper and eventually kill the fuzz, but again, PAIN IN THE REAR. Right now, when I am using aramid, I get the best trim by waiting till the epoxy is about 80% to semi-hard (full cure takes hours longer, basically wait until it is almost tack free on the surface) and then cut the edge with a brand new exacto #11 blade or other razor blade as shape allows. A #11 cuts well for about 10-20 inches before needing to be replaced (5oz aramid woven cloth). cutting the aramid fabric is another area. buy the correct shears to cut it if you value your sanity. any other method simply leaves a mess. (my shears are down to about .5 inches where they cut, the rest is too dull) in our applications, stiffness (with the exception noted above) can be better achieved at a lower cost with fiberglass and a core material (balsa, foam, etc) than either other option.
Greg, you are probably in the top 5% of the smartest people I know. But it's chisels Hehe. Signed, Woodworker Tugboat
The best composite I have found so far is G10, also known as garrolite. It is basically the epoxy version of circuit board material. It comes as a flat sheet in several thicknesses and colors and sizes, I get mine from McMaster Carr. 1/32 thick is almost completely resistant to bb impact and makes a good deck material for destroyers and small ships. 1/16 thick is completely impact resistant, not even taking a dimple. I use 1/16 for vertical surfaces and battleship decking. 1/8 inch thick is good for heavy duty structural work like gearboxes and cross braces. For use, it can be shaped easily with files or sanding blocks but for cutting you need will need a carbide cutting wheel. It will eat bandsaw blades in a few feet of cutting. It glues securely with rubber filled CA glue or epoxy. It is chemically resistant to most solvents you would put in your boat. It can be tapped. The downside is the gritty dust. Make sure you wear a mask, and expect the dust to get everywhere. Check out the build thread for my Nagato to see what you can do with it. I built everything in the boat out of it, and even replaced the fiberglass bottom where it was warped too much for my liking. Ron Hunt
I expect you can probably cut 30 to 60 feet through the 1/32 before ruining a bandsaw blade. Depends on how fast the blade is moving, how aggressive the cut and how long the blade is. I prefer to try to keep my blades sharp by using them on proper materials, otherwise I end up with a bunch of dull blades that never seem to get replaced. On my jig saw I can only go at most 18 inches before the teeth in the cutting area are completely gone. I really recommend carbide wheels, they slice through it like butter and don't load up or wear out. I still use the first one I bought. This stuff is probably upwards of 70% to 80% compressed layers of fiberglass cloth and acts closer to cutting rock than epoxy and gives it crazy good impact resistance. Ron Hunt
Ron, Are you using: 85315K131 Or 8491K7 Or 9910T15 Or 8667K241 There are a lot of choices. What type of carbide cutting wheel (dremel or right angle grinder)?
Yep there are a bazillion types. If you type in garrolite in the search box on mcmaster.com it comes up with 10 configurations. I used G-10/FR4 grade. Last couple of 1/16" sheets I got were 85345k51 in black, the color makes it easy to cover any scratches you inadvertently make with a sharpie. I dont think the exact grade makes a whole lot of difference for our use as long as you make sure it is made from fiberglass and epoxy and not paper and phenol. It isn't super cheap at $78 for a 36x48 1/16" sheet but it is flat, durable, attractive looking and doesn't require waterproofing. I expect my Nagato hull will outlast me. Ron Hunt
Thanks guys, this is good information. I am still researching an alternative to fiberglass, and haven't come up with much that looks feasible for what I'm wanting. I was looking for something lighter and thinner than fiberglass, just as strong and impact resistant, and flexible enough during application that it could be wrapped around corners. (Right after I found such a material, I was planning a hunting trip to capture several unicorns so I could take them to Santa Clause to distribute to all the good boy and girl leprechauns.) The reasoning was I wanted to use it to reinforce the bottom of the Hull, ribs, and caprail on a small boat (Orfey Class Destroyer), which would be a test bed for an even smaller boat in the future if the destroyer is succsessful. As Greg said, it seems that carbon fiber is perfect.... except the impact resistance isn't good, and apparently, when it fails due to impact, does so in spectacular fashion. I'm wondering what the failure would look like from our type of hits would be though? Has anyone ever gotten any real world tests with it in that capacity? Kevlar, on the other hand, is roughly the same density as carbon fiber, but has awesome impact resistance, especially the ballistic grade stuff (obviously). From what I've read and Greg confirmed, it isn't fun to work with, and doesn't sand at all. I think both materials are likely too stiff to wrap around some of the areas I wanted to use it, but that also seems to have a lot to do with the type of weave. I really don't know if the carbon fiber/ Kevlar hybrid cloth helps improve the impact capacity of the carbon fiber, adds stiffness to the Kevlar,or just looks way cool. I have to assume that the type of resin used has an effect on flexability and impact tolerance? What type did you use on the Kevlar Greg? Maybe I'll just make the darn things from kryptonite..... or anti matter..... or..??
I use west systems resin... the weave makes a big difference. if you are wanting something strong/stiff and light you may want to look at lightweight core materials.... an inner carbon layer with a foam or other core and an outer kevlar would be exceedingly stiff and tough. just make sure you cut the kevlar with a sharp blade when partially cured, and then apply a second layer (more thinner lighter weight layers are easier to cut) (I will put some more pictures of the kevlar on my Littorio up soon when I have a chance to work on it again) a good carbon or kevlar weave will conform quite nicely if chosen correctly. one thing I have been considering but I have not found the right options is for a semirigid rubber layer over the outside of the composite to reduce the peak load on the composite.... I have not found either a suitable paint on elastomer or sheet that could be conformed and stuck... with that said, I have, when properly directed (generally over a beer), considered making ribs and caprails out of semirigid rubber backed with a skeleton of composite... There are a host of issues (many bonding related) that would crop up in that, but it has been running around in my brain for a while.
Cloth inserted black rubber works great for impact resistance, paintability, and glues well. It makes great internal armor. Glued to the outside of a foam or stick superstructure it makes it completely bb proof, and makes good splinter shields and walls. It might be too flexible for the usage you want though without a lot of support to maintain curvature. I have found it in 1/32" thick sheet 20 years ago at a surplus place but haven't been able to find anything suitable thinner than 1/16" online after several attempts. It is sometimes used for truck bed liner, under roofing, for outdoor signs. Anybody got any idea where to find some in 1/32"? Ron Hunt
Yeah, the silicone isn't really suitable since stuff doesn't stick to it too well. What I found before was nitrile or buna-n or maybe neoprene. It is hard to positively identify. Ron Hunt
Any body ever try "S Glass"? Its fiberglass, but significantly stronger and lighter due to a different glass fiber used. Unfortunately I'm assuming that makes it significantly less fun to work with also? Harder to get it to conform around contours as well probably. Seems like it would be a good compromise between typical "E Glass" fiberglass and carbon fiber. I'll continue to look into it.
I think that "significantly stronger" is not really that much (20%) for our purposes. I have worked with both and noticed no difference in our applications either in strength or impact resistance. the weave/weight is the biggest contributor to good conforming for any of the glasses.
Yep Greg, that's in the range I have read on the specs for the material, depending on where the information comes from it seems to vary considerably. I have seen claims for anywhere between 18% - 40% stronger, and claims of 20% lighter to some that say it is actually heavier!? I came across a site somewhere that listed the material density for both, and the s glass was listed as somewhere around 15% lighter. I also saw a n s glass / carbon fiber hybrid somewhere also....... what's your thoughts on that Greg? I realize that we are literally talking tiny gains here and there. The thought I'm having here is that on the bigger boats, it truely doesn't matter a bit, but on a boat that is around 2 feet long and just over 2 inches wide, I have to do the best I can now, if I'm overweight or not as strong as I hoped later, I can't tale it off or add more if I'm already at weight. On top of that, again, I'm hoping to build something smaller next if I don't fall flat on my face with this one, so lessons learned here may go a long way! Thanks for all your input so far, it has been very helpful and insightful.
for a seriously weight constrained boat, I would use glass on the outside with carbon reinforcement inside, protected properly with a closed cell foam layer ontop if necessary. I might try kevlar but it depends. the best way to figure out exactly what will work for you is to build small (say 3sq inch) samples of what you want to try and play with them (shoot them, break them, just get a feel for the material) from that you should be able to develop a good setup and the skills to make it.
Thats a good point, i could use a fairly light fiberglass cloth on the outside, and carbon fiber on the inside, just to get the stiffness without the weight. I have very little desire to use aramid, from what you wrote and what I've read elsewhere, its a pain to cut, and is just slightly harder to sand than the average sidewalk.....
The trick with sanding the aramid to remove fuzz is to hit it with very fine sandpaper and make sure the cloth is resin impregnated.... still a pain.
