Not an April Fool's day joke

For no good reason I've idly thought about making the upper layer on the coaming of my upcoming project out of carbon fibre, purely as a visual thing.

 Talking to a mate about this yesterday, he raised his eyebrows and suggested this would make the craft – and me in it! – liable to lightning strikes if I was caught ‘out there’ in a thunderstorm (which are frequent in this sub-tropical part o’ the world). He went on to say that users of carbon fibre fishing-rods (which he is) and carbon fibre golf clubs are all well aware of this phenomenon and react accordingly when such weather threatens.    My response is that if you’re outside anyway and holding a long thin object up into the air, you’re possible a good target for a lightning strike anyway, carbon fibre or not! But - purely for fun and info, any comments on this?   And more seriously - can anyone suggest a source of info on using this material as I never have done so before?   Many thanks on this. Stay unstruck! 


4 replies:

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RE: Not an April Fool's day joke


You are correct that shape is more important than composition. Any shape which reduces the amount of charge needed to ionize the air between the ground and a cloud is a lightning attractor. There are 2 main ways to do this - first, locally collect more charge; second, reduce the amount of air between the ground and the cloud. Fishing poles and golf clubs fall into the second category. When they are raised on high, they reduce the amount of insulating air between the cloud and the ground, thereby giving the electrical charge a locally easier path to follow. Material makes no difference in that case.

In your kayak, what makes you most susceptible to lightning is you sticking up above the water level. The coaming and coaming material are irrelevant. Your paddle is probably the greatest danger point because it typically rises above your head and because it comes to a sharp edge (which concentrates the charge). Your head, being round, has a reduced charge concentration. That's why flagpoles have round balls on top, to reduce the chance of lightning strikes.

Finally, carbon fiber is amazing stuff. It gets almost unbelievably stiff if all you're used to working with is glass. There are some differences between the way it handles, compared to glass. First, it doesn't wet out the same way. It doesn't absorb epoxy as readily as glass, nor does it turn transparent. You have to work a bit harder to make sure that the epoxy gets consolidated into the fiber. Next, whenyou cut it, little black threads go flying everywhere. Always wear a dust mask since there is an inhalation danger. Finally, epoxy-coated CF fibers are very sharp and brittle. If you don't handle it carefully, you could end up with invisible splinters in your hands.

Because CF is so brittle, you may want to cover it with a layer of 3 to 4 oz. glass to protect it.

Have fun, it's cool stuff.


My CF mastbuilding page

Soller Composites How-to pages


RE: Not an April Fool's day joke

Thanks, Laszlo - I thought it was a bit of a red herring - and of course had quite overlooked the 'paddle in the air' point you make.  


I've read your blog on c-f mast making before - olive oil and all! - and will re-read it over the Easter break to glean some thoughts and no doubt tips and hints.   The Soller page was useful, too, and will also be re-read.   Much appreciated.


Happy Easter hols to all...



RE: Not an April Fool's day joke

There is an element of electrical danger with CF. Not to you but to your power tools! I wouldn't cut CF with any tools I cared about because the CF dust can easily short out your motors.

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