thanks for that. So for my task either plain or twill 200g whatever is around. whats the story with the 3k 12k ?
Select to expand quoteolskool said..
I bought 200gsm twill carbon recently. 1m x 1.2m . $40. Perfectly matched a Severne mast i was repairing.
This relates to 5.8 oz per yard, which is 197.9 g/m 2, in my Language.
which is peachy keen. If cheaper a less one would do , and double up, on glass E or S glass.
no set formula, but 2 posts mention this carbon which is fine and dandy .
Select to expand quotegofaster said..
thanks for that. So for my task either plain or twill 200g whatever is around. whats the story with the 3k 12k ?
its the number of fibres in one tow.
3K has 3000 fibres in the parts they weave to make cloth, so that "strand" is about 2mm (?) wide- cant measure one right now.
12K has 4 times as many fibres per woven strand and its much thicker cloth.
Basically all your windsurf board carbon or CK will be near enough 200gsm 3K
If you see the wide flat stuff there the strands are about 8mm wide, looks like a big black tablecloth - its the expensive 12K stuff (and may even be TexTreme that we can't buy here) 
Select to expand quotegofaster said..
thanks for that. So for my task either plain or twill 200g whatever is around. whats the story with the 3k 12k ?
I'm not sure of this, so I'm taking a very wild guess. I suspect that 3k has 3mm wide threads, and 12k is 12mm wide. The wider threads are also thinner, and the cloth sits flatter, but the stuff I had was extremely hard to wet out. I have no idea if that is a characteristic of all 12k weaves.
To be on the safe side, I'd stick with 3k
NUP!!!!! Got that all wrong!
the nu,ber before the "k" represents the number of filaments in the thread. explained here.
Select to expand quoteMark _australia said..
^^^ Yep all kinds of ways will work.
gofaster- you're onto it.
I can send u some corecell offcut big enough if you want - or maybe somebody close to you will pipe up? I remember how hard it was when I needed just a little bit of something....
Don't worry about sanding the kevlar, it will come off but just leave fluff, which will be under the laminate you add anyway. After the corecell is bonded on, try to sand out the top laminate which is say 1mm thick to make a 20mm ish bevel......... sanding disc in angle grinder goes well, a variable speed 7" sander/polisher much better
Then you will cut you carbon or CK exact, then next layer of 4oz glass say 1cm larger all round and same with next. After that you can add a layer of glass over the whole job to be say 5cm bigger al round, and that will be easy to blend in as its about 0.2mm thick .... won't see it.
If you really want to go nuts I could send u some CK offcut that matches (they don't sell the H-beam looking pattern in Australia) and corecell...
but as per decrepits suggestion, normal 200gm carbon will be fine and less hassle.
Ok so I'm about to do this. I've done the foam and it looks good. I've made paper patterns of the CF and glass layers, will cut the cloth and lay it up tomorrow. Extra piece of CF between the footstraps. A question - the final glass layer going over the whole lot - this layer will extend around to the bottom of the board. Should I be sanding the board area this goes on in order to blend in better, or will it be ok to just go on top of the bottom (of the board) surface?
Select to expand quotegofaster said.. >>>A question - the final glass layer going over the whole lot - this layer will extend around to the bottom of the board. Should I be sanding the board area this goes on in order to blend in better, or will it be ok to just go on top of the bottom (of the board) surface?
I think I'm the exception in this, I sand a small rebate for the overlapping glass, so the bottom ends up flat.
I think the standard construction is to trim it at the end of the tuck, so there's no overlap to the bottom of the board to worry about.
Select to expand quotedecrepit said..gofaster said.. >>>A question - the final glass layer going over the whole lot - this layer will extend around to the bottom of the board. Should I be sanding the board area this goes on in order to blend in better, or will it be ok to just go on top of the bottom (of the board) surface?
I think I'm the exception in this, I sand a small rebate for the overlapping glass, so the bottom ends up flat.
I think the standard construction is to trim it at the end of the tuck, so there's no overlap to the bottom of the board to worry about.
Gives a good sharp edge stopping at the tuck.
On new board you:
sand the top lap (where the bottom glass has come around to about where a deck grip line would be) so its blended in a bit. does not take much as 2 x 4oz is pretty thin.
Sand all the rails lightly and wash well.
Mask on the bottom of the board at the rail tuck line.
laminate the top to the tuck line. Any extra that has gone around the bottom is then easily sanded off later by sanding to the tape, thus not touching the bottom laminate
I am presuming the bottom glass that would wrap around the deck grip line has been removed? So you will need to double laminate the rails basically.
Thus it is often easier to fix the rails first and then the top. This assists in keeping rocker correct also. So really need pics of what you've cut away......
Photos attached. There is 1 layer of CK. There was a tough plastic coating over the white. I sanded it off and maybe I should have left the white but I don't think it matters
You've done a really neat job there.
I'd just sand back the CK for about 20-50mm all around to get a nice bevel then laminate 1x CK and 2x 4oz. Might need extra layer of CK underfoot. Make the last layer of glass quite a bit bigger to tie it all together nicely.
you haven't attacked the rails too much so two extra layer of glass on rail should do it.
Did the laminating today.Put some PE plastic over the finished layup, squeegeed it out, and put about 30kg sand bags on top.I had been worried that I hadn't used enough resin but definately not the case as plenty rose to the surface.
One question- I cut the first CF cloth layer to exactly fit the cut away shape in the CK deck-I hope I didn't misunderstand and it should have overlapped?
Yes you need a nice bevel (skarf joint) it should have overlapped. The more the better.
Of course depends on the use of the board- if you are going to jump it hard then its likely it will break along the CK join.
For flatwater freeride / light freestyle its probably going to be fine.
For safety now as you haven't overlapped I'd probably do the glass from mast track to behind the front footstraps in a big diamond. The extra 200g won't be felt bit it will help with strength
Select to expand quoteforceten said..
Pour foam... I have never injected it.
Me neither, sniffing glue is as far as I will go.
Select to expand quoteMark _australia said..
Yes you need a nice bevel (skarf joint) it should have overlapped. The more the better.
Of course depends on the use of the board- if you are going to jump it hard then its likely it will break along the CK join.
For flatwater freeride / light freestyle its probably going to be fine.
For safety now as you haven't overlapped I'd probably do the glass from mast track to behind the front footstraps in a big diamond. The extra 200g won't be felt bit it will help with strength
Ok that was a big stuff up.So I ground out a 50mm wide v bevel around the CK patch junction and laid a CF strip, then glassed over. Looks right now. Proof will be in the jumping...
My problem now is finding the footstrap holes under the carbon. I thought I knew where they were but I'm not at all sure now...
On my repairs you'ii see texta cross hairs ruled right through the repair area to the unaffected parts. And yes while the resin is still wet you can probe around the intersection of your lines with a sharp implement, and open up the weave a bit so it's visible after it's set.
Yes we've all been there. Even with a big template I sometimes take a while to find them on a new board.
About a 2 - 2.5mm dia nail in vice grips and push hard. Once you find one, its 25mm spacing on holes
Select to expand quotegofaster said..Mark _australia said..
Yes you need a nice bevel (skarf joint) it should have overlapped. The more the better.
Of course depends on the use of the board- if you are going to jump it hard then its likely it will break along the CK join.
For flatwater freeride / light freestyle its probably going to be fine.
For safety now as you haven't overlapped I'd probably do the glass from mast track to behind the front footstraps in a big diamond. The extra 200g won't be felt bit it will help with strength
Ok that was a big stuff up.So I ground out a 50mm wide v bevel around the CK patch junction and laid a CF strip, then glassed over. Looks right now. Proof will be in the jumping...
My problem now is finding the footstrap holes under the carbon. I thought I knew where they were but I'm not at all sure now...
Toothpicks are the go. Poke them in the hole, snap it off and leaves you with a bump in the cured laminate which is easily drilled out while finding the holes.
I tried different methods of finding the holes - like leaving the board outside so the dew would show the footstrap blocks because of the different insulating properties compared to the board foam but it didn't quite work. What did work was putting a fairing coat on the area- clear resin and q cells - the white gloss finish when cured made the footstrap blocks show up clearly - spectral reflection.
Must be minute variation in height in the surface.
Many thanks to those who helped me on this project. Sanding, a coat of paint and some grip and I'm finished. Good project-learnt a lot.
I is an engineer .
5 minutes thinking will save 5 hours work .
Nails cant fails 
, ( yeah , I made that up myself ).
PS , long nails , or coat hanger wire help , ( pre glued , contact cement , ) , place deck pads perfectly .
Select to expand quotekamel8000 said..gofaster said..
Went to buy carbon cloth - faced with lots of different ones. What should I be using for this repair?
The underlying cloth is a tension element in the sandwich construction. If you want to restore full construction integrity, there really should be an overlap, (about 3cm should do), between the good part of the old and new cloth you put in. The cracks where the sandwich has failed is primarily in this underlying cloth, so not tying the repair into the good good cloth will lead to a fairly quick fail.
Yes did that. What surprised me was that this underlying glass layer was only maybe 200mm wide, not right across the board.
Select to expand quotegofaster said..
What surprised me was that this underlying glass layer was only maybe 200mm wide, not right across the board.
That would really surprise me as well, I've repaired lots of boards and never seen that.
