My last repair worked so well thanks to the advice on this forum that I plan to repair this crushed rail myself. I plan to use a dremel to carefully remove the crushed material, I'll probably end up with a diamond shape to repair. I then plan to sand the edges and then fill the hole with pour foam, sand smooth and then glass with 1 layer of carbon and one layer of S glass. Does that sound reasonable? Any other ideas and advice? How much past the repair area should I sand?

First i would only remove last layer and try to keep most of inner materials only remove what is break. Then i would flow some fluid epoxy micro slurry in to hang up every thing together. Then i would use an epoxy microsphere+microfiber+silica mastic paste to fill in and reshape. Then lam many layers of fiber glass and carbon staggered. I would go at least 5cm around on intact board skin. Look at this:
sup.star-board.com/fr/paddleboarding-how-to/how-to-repair-a-hard-paddle-board/

Use more glass than you think so you definitely 100% cover the the fluff that innegra will make in first sanding..

Then when sanding after glassing be sooooo careful not to hit the innegra again (you will) and end up with a fluff perimeter (you will)
After that happens 3x in as many days you will be in tears and eventually it works out.

Post pics.

Question remains... What happened? Collision with another foil or fin?

Hope you manage to repair it.

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Mark _australia said..
Use more glass than you think so you definitely 100% cover the the fluff that innegra will make in first sanding..

Then when sanding after glassing be sooooo careful not to hit the innegra again (you will) and end up with a fluff perimeter (you will)
After that happens 3x in as many days you will be in tears and eventually it works out.

Post pics.

Is fluff perimeter from over sanding just an issue with carbon? Making the over sanding of glass much less of an issue?

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thedoor said..
Is fluff perimeter from over sanding just an issue with carbon? Making the over sanding of glass much less of an issue?

I've only noticed, "fluff" when sanding kevlar. never had any fluff with carbon, it sands the same as glass.

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thedoor said..

Mark _australia said..
Use more glass than you think so you definitely 100% cover the the fluff that innegra will make in first sanding..

Then when sanding after glassing be sooooo careful not to hit the innegra again (you will) and end up with a fluff perimeter (you will)
After that happens 3x in as many days you will be in tears and eventually it works out.

Post pics.

Is fluff perimeter from over sanding just an issue with carbon? Making the over sanding of glass much less of an issue?

It's the innegra that'll fluff out. Starboard use/d it on the rails of their boards. Like decrepit said, carbon sands up just fine like fibreglass. The times I've had to do it, it took a couple of goes to learn when to stop sanding.

getting rid of the fluff is a pita, not too bad if you're putting layers of glass over it. but near thesurface, you have to shave it with an extremely sharp blade. if it's on the surface, after shaving, spray with a paint that shrinks when it dries. That will pull the fluff down, repeat shaving and spraying until fluff disappears. AND DON'T sand!!!!!

And u used to have some wiggle room with resin over the top but no more. In the name of weight reduction they are getting really good at making that super flat so there is only clear paint over. a verrry light rub that used to be ok isn't now . hardly touch it and the innegra will be exposed

Ok cheers

What is the difference between microsphere and microfiber and silica and Q cell?

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ptsf1111 said..
Question remains... What happened? Collision with another foil or fin?

I'm not sure exactly what caused it since it is on the underside of the board. I broke my mast and extension and boom in the waves. The adjustment ring on the extension is metal, so possibly that got smashed into the rail by the waves after the extension broke?

Amazingly the sail was the only part that came out unscathed.

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philn said..
What is the difference between microsphere and microfiber and silica and Q cell?

Microsphere are bubble of glass or quartz (Qcell) or plastic. Add in resin it increase volume for near no weight increase. Reduce density, easier to sand for finish. Microfiber like floks Cotton increase strengh. Silica more exactly fume silica add in resin increase viscosity without modify other resin properties so much.

That sounds brutal, hope you're ok!

If you ever get fluff from sanding Kevlar (not sure about innegra) paint the fluff with resin and let it set. Once firm/hard, trim the lumps down flat with a Stanley or really sharp plane blade. Laminate over with a 4oz or similar then don't F'n sand through the glass-over.