Hurricane Damaged Boats

Lars, is this what they call Tensile Failure and Flexural Failure of the carbon fiber structure?
Arnie

I don´t know what they call it, but carbon in bottoms and stringers are often laid as longitudinal cords which is stiffening like a torsion bar. But if you hit it from the side it will easily crack. This is why you have kevlar as a woven fibre where such impacts are expected. All laminated in epoxy or vinylester (before normally polyester) together with different glassfibre qualities, some are prefab with carbon cords integrated.

Thanks, Lars.

I didn't chime in on this thread Arnie because the answers from Lars were so complete, it wasn't necessary.

I’d like to add there are many different types of carbon fiber cloths for different applications, ranging from filament wound, to plain weaves, woven twills and even... chopped. As Lars said, CF is mostly used for structural rigidity, but its impact resistance suffers because carbon fibers are brittle in nature. The molecular structure of carbon under compression usually results in breaking, not bending.

There are some drawbacks to building hulls from carbon as well. It’s a difficult material to saturate with resin, especially around compound curves and its shear compression, as well as impact tolerance is inferior to glass, and especially Kevlar. While Kevlar has a greater resistance to puncture, it doesn’t mix well with water. It has a tendency to wick, unless both sides of the cloth are bonded or laminated with a material impervious to absorption.

While carbon is a good choice for ultimate strength to weight, such as racing sailboats and performance aircraft, it’s not the best solution for our world, where pilings are looking to leave their mark on rub-rails. There are some other issues with carbon too. Carbon is a conductor of both electricity and frequency. You have to be extra careful when wiring a carbon hull. Wires tend to chaff easily when exposed to carbon laminate edges. And insulating a rigid structure from the sound and vibration inherent where large motors are present is an even bigger challenge with carbon, which has resonant properties bordering a sub-woofer.

And last, there have been some long-term studies over carbon fatigue from U/V exposure. While this is generally not an issue for a gel-coated hull, it can be an issue when carbon is painted. More importantly, when epoxy resins are exposed to long-term heat or U/V, they can become more brittle. I encountered this scenario a few years ago with disastrous results.

Carl (Lars and Codger too),
Thanks for the additional info.
I'm learning a lot from you guys.
Arnie