Any ideas on fixing this

Ouch! How did you do that?

I think you might have to fill it with an epoxy paste, and then drill the holes where they need to be. You would then grind it back to where the carbon is now, and then add layers of carbon to it, and vacuum it down. You of course are going to have to then reshape it so that the outside diameter still fits your boom.

Chamfer the edges, insert a balloon and blow up, glass and vac as per normal

Great photo for the FUNNY IMAGES thread !

Cameron just invented a new adjustable outhaul system
or perhaps
Drill a couple of holes on the side at 45 deg and fit a slotbox fin.

See you on Wednesday

Flip it over and just drill new holes for your sail sizes.

It looks like a big sail boom. It might be easier/safer to replace the whole broken tube. If its a single pin adjuster, it should pretty easy find a second hand carbon rear-end and adapt it to fit yours.

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FormulaNova said..
Ouch! How did you do that?

I think you might have to fill it with an epoxy paste, and then drill the holes where they need to be. You would then grind it back to where the carbon is now, and then add layers of carbon to it, and vacuum it down. You of course are going to have to then reshape it so that the outside diameter still fits your boom.

Its a well used boom, currently on its 3rd mast clamp and 2nd regrip.

I only noticed it yesterday, the picture is after I removed the damaged carbon. Have felt something slip a few times whilst sailing recently, I thought it was the adjustable outhaul slipping in the cleat. I guess the positive is I don't need to replace the cleats

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R1DER said..
Flip it over and just drill new holes for your sail sizes.

Good idea, I will keep that as a backup if I botch the repair

Fill the gap with pu foam from a can, after setting remove foam and level with inside boom . sand the sides from the part you need to rebuild. cut carbon fiber strips and mix epoxy resin, rebuild from the foam up layering the wetted out strips, vaccuum, cure, sand , drill , surf.
walk in the park

Replace it, I doubt any kind of repair would return it to original strength, they aren't supposed to last forever, nothing is for that matter.

Make up a 'c' section pipe long enough to bridge across damage to slip inside

roughen up interior and glue inside

fill and fair fair the exterior void

cheers jeff

it can be fixed with some carbon cloth and resin ....

i had one like that ,,,not as bad ...but i had 3 sail all in 203 205& 200.

I drilled a few holes and pop riveted it ..and just use it for them ..its a stiff carbon boom now set for my 7.0.,6,3 and 6.5 .

i hope my harness lines last for a while ...please note i do have other booms .

Could you slide a short aluminium sleeve up inside?

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Agrid said..
Could you slide a short aluminium sleeve up inside?

NOT!!!!! a good idea, there is electrolysis between carbon and alli, maybe a quick very temp fix, but leave it in there and there'll be big problems down the track.
I had a 2nd hand carbon boom that somebody had stuck an alli head on. Everything just fell apart at the join, I had to completely rebuild the head end of the arms.

Not sure how I'd tackle this problem though, there's been some good suggestions, but I don't particularly like turning it over and drilling holes on the other side. Probably OK if you never extend the boom past the area with holes both sides, but if you do I can imagine it snapping there.

Inserting a carbon tube inside the area could work, (but finding one the right diameter could be tricky), then filling up on top of it with something hard enough not to wear away.
On that note, wear like you have shouldn't happen if the pins are locating correctly. The boom of mine previously mentioned, also used to slip, and wear the holes. The pins had a rounded end, and it was only the rounded end that engaged the holes. I found some longer pins that went fully into the holes, and no more wear or slipping.

OK where was I?
Yes, think I'd fill the damaged area of the tube with something, I'd probably use bog rather that expanding foam, because if you use microfibers instead of qcell it's going to be fairly hard, and you can just drill into that without having to do a whole rebuild. It will also give the inside of the tube compressive strength, and stop the area with the long slot collapsing under load. Just make sure you drill deep enough without going all the way through.

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decrepit said..

Agrid said..
Could you slide a short aluminium sleeve up inside?

NOT!!!!! a good idea, there is electrolysis between carbon and alli, maybe a quick very temp fix, but leave it in there and there'll be big problems down the track.
I had a 2nd hand carbon boom that somebody had stuck an alli head on. Everything just fell apart at the join, I had to completely rebuild the head end of the arms.

Not sure how I'd tackle this problem though, there's been some good suggestions, but I don't particularly like turning it over and drilling holes on the other side. Probably OK if you never extend the boom past the area with holes both sides, but if you do I can imagine it snapping there.

Inserting a carbon tube inside the area could work, (but finding one the right diameter could be tricky), then filling up on top of it with something hard enough not to wear away.
On that note, wear like you have shouldn't happen if the pins are locating correctly. The boom of mine previously mentioned, also used to slip, and wear the holes. The pins had a rounded end, and it was only the rounded end that engaged the holes. I found some longer pins that went fully into the holes, and no more wear or slipping.

OK where was I?
Yes, think I'd fill the damaged area of the tube with something, I'd probably use bog rather that expanding foam, because if you use microfibers instead of qcell it's going to be fairly hard, and you can just drill into that without having to do a whole rebuild. It will also give the inside of the tube compressive strength, and stop the area with the long slot collapsing under load. Just make sure you drill deep enough without going all the way through.

I am thinking of using a section of electrical conduit and wrapping carbon around it to create a tube the correct diameter to slip inside.

Then glue it in with epoxy paste, fill the void with carbon or glass strips then a piece or two od cloth over the top oversized and feathered to match the outer diameter then drill holes.

What do you think.

I will check the pins as this boom is on its third or fourth set. The holes on the other side are good and show very little wear

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Imax1 said..
I would pick out the foam in the middle about 5 mm under the wall section then with bent nail hack out some foam undercutting sideways 5 mm all around.
With scissors finely chop some fibreglass cloth or mat ,about half of a fluffy cup.
Make a mix of Araldyte glue and mix in some of the glass fibres until you have a thick bog , the more glass the better but not dry.
With a icy pole stick stuff it in and under the tube and fill the slot and pile it up a little.
Next day file it smooth and drill the holes.
The glue and glass mix will stick and be quite tough.

Cammd, i dig the pvc use . Doesnt rust, doesnt corrode, easy to work with.Im a sparky n use pvc electrical components to fix n make all kinds of odd things. Knife scabbards,berley bucket n muncher, mast spacer/protector, rodholders, containers to hold screws n bits.Endless really..Just criss cross score the pvc surface with a knife tip. So the epoxy has some kind of 'key' to the conduit surface. I used 40mm md conduit with bamboo jammed inside to make up a kids rig mast. 18months n still going strong.

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decrepit said..

Agrid said..
Could you slide a short aluminium sleeve up inside?

NOT!!!!! a good idea, there is electrolysis between carbon and alli, maybe a quick very temp fix, but leave it in there and there'll be big problems down the track.
I had a 2nd hand carbon boom that somebody had stuck an alli head on. Everything just fell apart at the join, I had to completely rebuild the head end of the arms.

Good to know, I thought carbon would be inert to electrolysis.

I too was worried about turning the boom and round and drilling new holes because that long slit would weaken things. Thats why I was thinking of a sleeve inside.

Just put a stainless hose clamp around the tail and tighten it up when the boom is set at the correct length and use it that way until you can afford/want (assumption) to buy a new boom.

Carbon covered conduit inserted and now glued in with west system g flex.
My question is should I enlarge the section for repair by making it wider than the holes that will be re drilled. Would that make the repair stronger

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cammd said..


Carbon covered conduit inserted and now glued in with west system g flex.
My question is should I enlarge the section for repair by making it wider than the holes that will be re drilled. Would that make the repair stronger

you need to taper the whole area and build up layers other wise you will have a key piece which can be pushed along the slot under presure .start with a big piece of carbon first and small last once they are laid to the correct fill wrap it with duck tape to force it in to the join ,after it is set sand down the area slightly smaller and put 1 more layer off carbon and sand to correct size

I liked the idea of turning the boom over a drilling only required holes, having inserted something to stop the damaged section collapsing. I reckon the sleeve will move for sure if the attachment is to it. Having said that, I've had no experience with this sort of repair.

I combine all methods:

Fill it with foam, sand out then lay up carbon and resin. Err on the side of more laminate thickness than the factory laid up as yours won't be as strong.

No need to vac, really tight taping will do.

Then flip and drill other side


I like your idea of the conduit with carbon so far, but at first glance I say DON'T laminate with g-flex its an adhesive not a laminating resin. They say "can be used" so to me thats a hmmmm

Try it out tomorrow

Very neat, great job. But have you checked the pins, and how far they engage the holes?

The previous damage looked like the pins may not have gone all the way in.

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Agrid said..
The previous damage looked like the pins may not have gone all the way in.

Exactly, that's why I asked if he'd checked them

Yes they do go all the way in.

I wonder if I didn't engage them correctly at one time or maybe the previous clips caused some damage when they got old. Usually the pins come loose or the clip cracks and you keep using it until the new ones are obtained. I did the rb words last year with gaffa tape holding it all together causeci didnt have new clips.

I keep spares on hand now

Just buy a new boom, every little creek, crack, or slip that you hear while using it will make you worry, taking your attention away from having worry free sailing. "What was that? I may have to go in and check my boom, I hope I make it in".
Not worth it, believe me I've tried stuff like that. Back in the late 80's I had a mast that would make these cracking sounds whenever I rotated the booms up to rigging level (tie on booms), so I shoved a piece of broken mast up inside the weakened mast to where the booms attached, with glue. It stopped the cracking noises while rigging, but I never trusted it, and got rid of it, not to mention the added weight.
It was not worry free sailing.
Also, what caused that kind of unusual wear? Something did, has that been addressed? Or are you just patching up something that shouldn't have happened in the first place? If you aren't sure what caused it, you're just wasting time.
I'm done.

Since were discussing boom repairs I have an easier one I need advice on.

the pop rivet attaching outhaul pulleys at the tail of the boom has corroded away so it's now only barely holding on relying on the shape of the assembly. It also looks like the pop rivet hole in the carbon has elongated a little.

whats the best way to fix this. Should I use an oversized pop rivet or fill it and use a screw....any suggestion welcome.

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Waiting4wind said..
Since were discussing boom repairs I have an easier one I need advice on.

the pop rivet attaching outhaul pulleys at the tail of the boom has corroded away so it's now only barely holding on relying on the shape of the assembly. It also looks like the pop rivet hole in the carbon has elongated a little.

whats the best way to fix this. Should I use an oversized pop rivet or fill it and use a screw....any suggestion welcome.

Stainless pop rivet. It has to be a snug fit in the hole or it wont work.