Drilling Carbon Fiber?

Want to add some deck rigging to an '04 carbon fiber Easy Rider Dolphin. Any cautions/techniques best to prevent cracks/chips? Thanks, Rick

In general
I don’t like putting extra holes in a hull and carbon fiber presents additional challenges as the cloth can snag and separate. One statement I can quote is as follows:

“For the best results for drilling holes in to fibre glass or carbon fibre use a diamond coated drill bit these are much sharper and stay sharper which means they cut the fibres easily without dragging them.”

I assume the newer the bit, the cleaner it will be going through the hull.


You should get clean holes in
carbon or glass laminate with just ordinary, new, sharp high speed bits. Drill speed slow to moderate.

Don’t worry about delamination. Though stiff, glass and carbon fibers will shear off easily. The resin will hold the rest together. And I wouldn’t do anything special about the holes, once they’ve been drilled. You don’t need to paint the edges with anything.

If you were drilling glass/Kevlar, a little bit more attention might be needed, because Kevlar fibers are very tough, and if your drilling were to get ham-handed, those tough fibers might pull loose of the resin near the hole. But even then, it wouldn’t amount to anything. Kaz of Millbrook builds S-glass/Kevlar boats, drills them to lace float bags, and everything holds up just fine.

Use masking tape

– Last Updated: Jul-13-13 1:47 PM EST –

On one or both sides to minimize chipping. I've had good success with both regular bits on a drill and the super high-speed drills with a RotoZip tool. The latter goes through like the hull is butter - good for cutting larger areas such as installing a new hatch, or just making a clean hole.

If you need to drill a wide hole, either use a special bit that has its own mini-pilot-hole drilling tip or start with a small bit then go up the size with bigger bits...

Depending on what you are attaching you can use wide rubber-faced stainless washers and a nut on the inside, not just the nut, so you have more surface area to pull against. Or use the self expanding rubber-coated bolts (forgot the name) - they work really well for deck rigging that will not see too much stress and do not require access to the underside of the deck.

Of course, you can go fancy and use fittings that are glassed-in.

And there is the option to glue on the outside carbon fittings - no drilling required and they are strong and light. Places like CLC boats sell them or make your own.

1000’s of holes drilled ZERO problems
put the bit where you want the hole, don’t let it slip and pull the trigger. Its done. No need to think after that.

Now if dealing with globbed on gelcoat or even if you not sure … REVERSE the bit through the gelcoat, when color change, forward bit as above … done.

Thanks all
Great tips. Not worrying as much now. R

use a backer …
… on the underside to secure fastners through .

Hardwood block larger than the footprint of the thing your attaching . This spreads the load that gets applied to the attachment … called a backer .