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Carbon Boom Snap- Repairable?
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Joined: 02 Jul 2012
Posts: 426
Location: Cabrillo Inside

PostPosted: Mon Aug 19, 2013 8:10 pm    Post subject: Reply with quote

First the mast now the boom?!? Formula looks expensive!
Hopefully you can fix it the boom.

2014 Cabrillo Beach GPS CS (inside)
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Joined: 29 Oct 2002
Posts: 1500

PostPosted: Tue Aug 20, 2013 8:55 pm    Post subject: Reply with quote

dvCali wrote:

As somebody else has mentioned: don't use aluminum. You could use a pre-made carbon tube, but I doubt you can get close enough tolerances to guarantee a good bonding between the broken part and the fix.

I'd suggest to use carbon tape (look toward the bottom of )

Take off the grip and sand the tubes for a good 6", do multiple carbon wraps with wet (epoxied) tape, and wrap the whole thing very tightly with electrician tape that you have "prepared" by putting some pin-holes in it. The excess epoxy will be squeezed out: it is a poor man vacuum bagging. For how many wraps, in what order do a little research. I am not sure if it is better to do separate wrappings and cures, but I suspect it is since the thickness of your repair should be at least as much as the thickness of the original tube. Would it work ... no so sure Embarassed Embarassed I personally would buy a new one or give the job to somebody that has quite a lot of experience with composites.

Yes, what DVcali said.

It looks like the transition between straight and bent tube cracked - the forward portion is manufactured separately - usually inside a mold, whereas the straight portion is wrapped around a mandrel. A repair would basically re-construct the connection between the two.

1+ Forget the aluminum. You can use a cork (2011 chateau whatever) as a temporary ferrule to keep the halves together and prevent epoxy seeping into the tube where the boom extension goes.

A wrap of carbon tape wetted out on a sheet of saran wrap works, but a triangular sheet of carbon cloth might be easier and give you a triple overlap in the center around the break.

Use a helix of tightly wound electrical tape to express all extra resin after wrapping and you'll also get a good finish that doesn't need sanding.

florian - ny22
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Joined: 10 Aug 2006
Posts: 64

PostPosted: Wed Aug 21, 2013 2:18 am    Post subject: Reply with quote

A nice trick for wrapping with the electrical tape is to first punch pinholes in it. Before unwrapping the tape, just take a pin and make lots of holes in the roll so it looks like a tennis grip.

Then, when you wrap the electrical tape around the epoxy, it will ooze through the holes rather than just between the edges.

To wet out the carbon, use a cheap foam paint roller but with the foam removed. The hard plastic roller is perfect for squeezing out excess epoxy from the carbon.

The 99cent store is great for getting these items as well as mixing cups, etc.

For my boom job, I used west system g-flex from west marine:

Easy to mix because it's 1:1. It's supposed to be slightly more flexible than regular epoxy but much more resilient and less likely to fail. When playing with the left overs after hardening it was indeed less brittle and hard to break.

It's definitely worth trying to fix the boom. The materials cost is not too much and you could have it as good as new. Plus, it's fun.
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Joined: 01 Mar 2011
Posts: 58
Location: St Petersburg Fl

PostPosted: Wed Aug 21, 2013 6:42 am    Post subject: Reply with quote

Douglass I've repaired a few Carbon SUP paddle shafts and the easiest way is to find a carbon tube that you can cut and slide into the two broken pieces. But before you do anything wash the inside of the boom tubes and the outside of the repair tube with soapy water and either a bottle brush or wet dry sand paper glued to a PVC pipe to remove any mold release wax. Then sand the inside of the tube with 60 or 80 grit Sand paper (Glued to PVC pipe, or a belt sander paper cut and rolled up works also) it need some scoring for the epoxy to grip. If you can find a broken tail end piece of a Chinook carbon boom then use that. Call some of the Wind surf shops you might find a piece. I take 4oz fiberglass and cut a few 1-2" wide strips and fold it over the end of the tube and slide it into the tube to see how it fits, Just enough so it's not a sloppy fit. (Dry fit) Then once you have the booms cut and cleaned up and ready for epoxy. Mix up a batch of epoxy I use west system slow cure. split the mixture so you can add Q-cell to half. Wet out the cloth on a piece of plastic sheeting, coat the inside of the boom tube do one end first, with non thickened epoxy, coat half of the repair tube with epoxy then drape cloth over tube smooth out cloth with acid brush. take a bit of the thickened epoxy and smear it inside of the tube right at the lip of the boom tube. Make sure the FB cloth is wetted out then slide the repair tube half way in. Wipe up excess epoxy with Acid brush let sit over night. Then repeat with the other section of boom tube. I'd do rear first, then fwd section. Then after the two are glued back together Sand the joint a bit and wrap the joint with Fiberglass and or a layer of carbon.
The only way to use aluminum as a sleeve is to wrap the aluminum with a few layers of fiberglass cloth and epoxy and that will act as a insulator between the carbon and the aluminum. You will still have normal corrosion problem but it won't be accelerated by the carbon fiber. That was the way Gulftech booms did there carbon wave boom front ends before they went to all carbon front ends. Hope this helps! Cheers Mike
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