Forums > Kitesurfing Foiling

How to repair a foil wing?

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Created by canucck > 9 months ago, 8 Jul 2018
canucck
2 posts
8 Jul 2018 9:21PM
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Hi,

I hope that someone on this board can help me with suggestions for a repair. I have a carbon fiber wing that I have damaged through multiple impacts on the sand bar here at Souris, PEI, Canada. I have been researching what others have done across multiple forums, and hope that someone here can provide me some recommedations. I have found some possible solutions below, and perhaps one of these is the best, or maybe there is another solution that should be used?

1. Epoxy - https://www.amazon.com/gp/product/B00QV7L820/ref=ox_sc_act_title_1?smid=A1T1R9Q3ML5YGI&psc=1 - would this provide structural integrity, given that the crack is on the front of the wing? Looks like an easy solution.

2. Superglue with baking soda - this is a posting from kiteforum: "To repair dents and cracks in airplane propellers to include surfboard dents masts etc, superglue can be used. First fill the dent with superglue, then sprinkle finely ground Sodium Bicarbonate(Baking Soda) on the surface of the glue. The glue instantly hardens 5 times stronger then normal superglue. Next brush off the excess Baking Soda with a brush then file or wet sand. If the void is not filled apply the process again until void has been removed. The process is cheap, fast and effective." - Check out this video to see it in practice,

- I was thinking that I could fill the crack with glue, clamp the wing to squeeze the crack tight and then coat with baking soda.

3. Ground carbon with epoxy

4. Carbon mat with epoxy

5. Carbon tape and epoxy (www.westmarine.com/buy/west-system--episize-unidirectional-carbon-tape--P004_120_004_506?recordNum=1)

6. Fiberglass mat with epoxy

Thanks for your help and expertise!



ice
VIC, 219 posts
9 Jul 2018 12:53PM
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that wing might be delaminating, not simply surface dents or scratches

more problematic

MrBlean
NSW, 10 posts
18 Jul 2018 4:09PM
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Note in the video he initially talked about filling chips, not cracks. At one point he said cracks then corrected himself. I would suggest this method is for cosmetic repairs only. Carbon fiber is an interesting material in that it derives it's strength from the long chain carbon molecules within it. Break those en masse and all structural integrity is lost. I would be inclined to stick a screwdriver blade into the crack and see if you can gently lever it wider. If you can, the crack is very deep and probably not capable of safe repair or lasting repair. If you try tonrepsir, anything other than a low viscosity liquid in the crack will effect the profile as you won't be able to clamp to the two sides back together in their original places.

canucck
2 posts
19 Jul 2018 10:23PM
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Hi, sorry for the delay in replying. Thank you ice and Mr Blean, for your comments.

RAL INN
VIC, 2880 posts
20 Jul 2018 5:56AM
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That pic looks more like a foam filled wing giving up the ghost.

Longfin
2 posts
20 Jul 2018 4:39PM
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canucck said..
Hi,

I hope that someone on this board can help me with suggestions for a repair. I have a carbon fiber wing that I have damaged through multiple impacts on the sand bar here at Souris, PEI, Canada. I have been researching what others have done across multiple forums, and hope that someone here can provide me some recommedations. I have found some possible solutions below, and perhaps one of these is the best, or maybe there is another solution that should be used?

1. Epoxy - https://www.amazon.com/gp/product/B00QV7L820/ref=ox_sc_act_title_1?smid=A1T1R9Q3ML5YGI&psc=1 - would this provide structural integrity, given that the crack is on the front of the wing? Looks like an easy solution.

2. Superglue with baking soda - this is a posting from kiteforum: "To repair dents and cracks in airplane propellers to include surfboard dents masts etc, superglue can be used. First fill the dent with superglue, then sprinkle finely ground Sodium Bicarbonate(Baking Soda) on the surface of the glue. The glue instantly hardens 5 times stronger then normal superglue. Next brush off the excess Baking Soda with a brush then file or wet sand. If the void is not filled apply the process again until void has been removed. The process is cheap, fast and effective." - Check out this video to see it in practice,
- I was thinking that I could fill the crack with glue, clamp the wing to squeeze the crack tight and then coat with baking soda.

3. Ground carbon with epoxy

4. Carbon mat with epoxy

5. Carbon tape and epoxy (www.westmarine.com/buy/west-system--episize-unidirectional-carbon-tape--P004_120_004_506?recordNum=1)

6. Fiberglass mat with epoxy

Thanks for your help and expertise!





Wrap it with CFibre and a top layer of fibreglass cloth( so you can sand it back to fibreglass and not carbon)
Use west system epoxy
Vacume bag for good bond

ZYX
94 posts
29 Jul 2018 6:19PM
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I agree with ice. It looks like delamination. I would contact the manufacturer for a refund or replacement because delamination is a quality issue. Composite material should not crack if processed correctly. If it cracks it means there is no structural fibers there. The crack is in the maximum shear stress and should be addressed by the design and process in the first place. However, it may be possible to fix it at home.
I would determine what kind of resin was used for this. If the wing is painted it may be cheap polyester resin like Naish co is using. Polyester is not water proof and scratching the paint may result in excessive water absorption. But polyester will cost you less for fixing it. Just make sure you paint it to prevent water contact with the internal structure.
You will get a better bond if you use the same resin. Polyester or vinylester resins may not be compatible with epoxy - may not bond well and will crack again. You can sand a small area of the wing ant test what resin gets a better adhesion to the material of the wing. Sanding is very critical for adhesion - need to expose the internal fibers so new resin will defuse between the fibers. Carbon laminates are particularly prompt for diffusion.
Wrapping will work as Longfin recommends but make sure you sand the area of warping well deep in order to get to the fibers and compensate for added material. When you apply cloth make sure the fibers are located diagonally - the best for shear stress, which is critical in this area. Use fiberglass only. Do not use carbon. Carbon as not as good for tension and shear as glass. When you sand it later you will expose carbon fibers and it is not good. Carbon fibers in laminate suck water. Glass - not so much. West system epoxy is good but not critical. Any structural resin is about the same properties. Laminate a sample before working on the wing to test the result. No need to vacuum - just wrap new laminate nicely with a clear tape while it is wet. Then sand it and paint it.
But I would fix it differently than longfin suggests. Without wrapping and sanding in order to keep the original hydrodynamic profile of the wing. Instructions:
Dive a wedge into the crack to see if delamination continues. You may be able to split the entire wing on two parts. Then sand blast both and glue them back together with a layer of fiberglass cloth between. Wax exterior surface before splitting so it will be easy to clean it after. Or mask tape it. Then just trim the edges and do not need to paint since the area will be very small. If it does not split I would cut 1-2mm slot along the entire crack min 10mm deep. Oscillating diamond or CBC blade used to remove grout on tiles will be the best tool to use. Pull fiber strings out of fiberglass cloth long enough for entire slot. Wet out the bundle of fibers with the correct resin. Make sure its is wet and remove excessive resin. Then place the wet glass-epoxy tow into the crack. Make sure it is all the way in. Add more wet fibers into it to fill the slot. Wrap around with clear tape.
Good luck.

snalberski
WA, 857 posts
1 Aug 2018 6:57PM
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Select to expand quote
XYZ said..
I agree with ice. It looks like delamination. I would contact the manufacturer for a refund or replacement because delamination is a quality issue. Composite material should not crack if processed correctly. If it cracks it means there is no structural fibers there. The crack is in the maximum shear stress and should be addressed by the design and process in the first place. However, it may be possible to fix it at home.
I would determine what kind of resin was used for this. If the wing is painted it may be cheap polyester resin like Naish co is using. Polyester is not water proof and scratching the paint may result in excessive water absorption. But polyester will cost you less for fixing it. Just make sure you paint it to prevent water contact with the internal structure.
You will get a better bond if you use the same resin. Polyester or vinylester resins may not be compatible with epoxy - may not bond well and will crack again. You can sand a small area of the wing ant test what resin gets a better adhesion to the material of the wing. Sanding is very critical for adhesion - need to expose the internal fibers so new resin will defuse between the fibers. Carbon laminates are particularly prompt for diffusion.
Wrapping will work as Longfin recommends but make sure you sand the area of warping well deep in order to get to the fibers and compensate for added material. When you apply cloth make sure the fibers are located diagonally - the best for shear stress, which is critical in this area. Use fiberglass only. Do not use carbon. Carbon as not as good for tension and shear as glass. When you sand it later you will expose carbon fibers and it is not good. Carbon fibers in laminate suck water. Glass - not so much. West system epoxy is good but not critical. Any structural resin is about the same properties. Laminate a sample before working on the wing to test the result. No need to vacuum - just wrap new laminate nicely with a clear tape while it is wet. Then sand it and paint it.
But I would fix it differently than longfin suggests. Without wrapping and sanding in order to keep the original hydrodynamic profile of the wing. Instructions:
Dive a wedge into the crack to see if delamination continues. You may be able to split the entire wing on two parts. Then sand blast both and glue them back together with a layer of fiberglass cloth between. Wax exterior surface before splitting so it will be easy to clean it after. Or mask tape it. Then just trim the edges and do not need to paint since the area will be very small. If it does not split I would cut 1-2mm slot along the entire crack min 10mm deep. Oscillating diamond or CBC blade used to remove grout on tiles will be the best tool to use. Pull fiber strings out of fiberglass cloth long enough for entire slot. Wet out the bundle of fibers with the correct resin. Make sure its is wet and remove excessive resin. Then place the wet glass-epoxy tow into the crack. Make sure it is all the way in. Add more wet fibers into it to fill the slot. Wrap around with clear tape.
Good luck.


Or you could just buy a new wing

ZYX
94 posts
6 Aug 2018 8:03PM
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Select to expand quote
snalberski said..
Or you could just buy a new wing


Correct!
Do all the manufacturers offer replacement wings? I do not see many wings offered. I am looking for a foil. Would you recommend a foil for Light Wind with ability to buy a new wing? Thanks.

KAOS69
WA, 1012 posts
15 Aug 2018 10:00AM
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anything can be fixed when the damage was this bad from a crack I thought that I would have to buy a new wing but when I found out the price of it it was a no brainer to repair it for a fraction of the cost reinforced with carbon layers of Glass vacuum bags etch primer 2 pack 6 months later still going strong better than the original

snalberski
WA, 857 posts
15 Aug 2018 1:16PM
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Select to expand quote
XYZ said..

snalberski said..
Or you could just buy a new wing



Correct!
Do all the manufacturers offer replacement wings? I do not see many wings offered. I am looking for a foil. Would you recommend a foil for Light Wind with ability to buy a new wing? Thanks.


Hey XYZ. I use J Shapes and highly rate and recommend their products. Their wings are one piece front/fuselage/stabiliser which offers stiffnes and simplicity. They have multiple options for wing size which will effect how early the foil rises and how late it will stall, but I'm not convinced there is such a thing as a light wind foil. They will all be highly efficient once up and flying. Its probably more about the kite you use in combination with the broader foilboard vs tt vs surfboard, and foilboard always wins.
Incidentally I had a similar looking crack on the Tuttle end of my J Shapes mast. I have used the mast for 2 seasons. I contacted Antoine from J Shapes and he repaired it and reconditioned the entire mast free of charge.
I use the J Shapes freeride wing but the cruizer might tick your boxes.



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"How to repair a foil wing?" started by canucck