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Split Carbon Masts


Trevor
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My recently acquired marblehead has shroudless C1, C2 and C3 rigs, that have splits in the lower section of the masts.  As I anticipate using these rarely for casual club racing, repair rather than replacement is preferred. Would pushing epoxy into the splits and/or sleeving be the way to go?  If replacement is recommended can I use the £12.50 per metre tube rather than the £60 per metre stuff?

Cheers

Trevor

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When I make up c/f masts, I have taken to epoxying  hardwood dowel into the bottom, far enough up to give the screws fixing the gooseneck something to bite into,

Once fixed, the gooseneck gets a top /bottom/middle wrap of carbon tow epoxied around it, then a piece of heat shrink tube over it to tidy it up.   The dowel is available off of Ebay as is the heat shrink, and all my c/f tube , resin etc comes from Easy  Composites.  I use their Woven Finish Roll Wrapped Carbon Fibre tubes, i.e the £12 end of the market.

Possibly , you could adapt some of the above to attempt repair before replacement

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There are two common types of cf tube.  Pultruded and roll wrapped.  Pultruded has the fibres orientated along the axis and is far stiffer in bending making it ideal for masts.  The drawback is that it is fairly weak in the other directions and very easy to split if you try and force another tube into it or don't reinforce the ends.  You could sleeve it but commercial grade tube is not precisely made and pultruded tubes don't usually fit inside one another easily.  If you want to sleeve it then you could use a roll wrapped tube as you only want to stabilise the outer tube, not add any more stiffness.  My limited experience is that roll wrapped tube is more likely to fit inside.  It also has a thicker resin coating and so can be sanded / turned down more before the fibres break through.  Your best bet however is to buy a new tube.  Pultruded tube can be had for little more than roll wrapped but you must use external reinforcement on the outer tube of a joint and internal reinforcement at the bottom of the mast.  You can get reasonably priced tube here:

https://www.bucks-composites.com/products/carbon-fibre-pultruded-hollow-round-tube-1-metre-long

The Sailsetc web-site has some good instructions and sizes for making masts.

https://www.sailsetc2.com/downloads/RP15E.pdf

The hardest part of making masts is getting the tubes to telescope nicely for the joins.  I use a lathe to turn down the inner tube but you can do it be careful sanding,  If you are going to risk doing it by drilling the outer tube you must reinforce it first.

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  • 5 months later...

Paint the outside of the spar with epoxy resin then whip the affected split zone, plus a bit further up with carbon  or kevlar tow and then paint over with epoxy.

This will create a high tensile hoop around the mast holding the existing parts together and prevent the split from travelling.  

hint if you need these to plug onto a smaller stub mast, use a polyethylene bung (can be made from parcel tape) in the end of the tube to stop the epoxy resin getting inside the tube and fouling the bayonet.

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