The used 2014 IS87 carbon I have recently bought turned out to be in structurally in poor condition. Crunchy delam between the straps and under the foot pad of the front strap. I'm sure I can see that resin (or something) has been injected between the straps on right side. The bottom has some pressure dings that have been filled faired out (I knew about these). The owner did not know of the structural issues (it does look great!) and gave me some money back to go towards repairing the board.

So with the help of the board lady website and existing posts on this forum I'm about embark on a repair (Inject foam to fix core, Vacuum sandwich foam + carbon etc and paint etc). I have done minor epoxy repairs in the past, but nothing like this before. I'm going to practice by repairing an old (20years) custom carbon fiber/Divinycell sandwich board, before taking a grinder to the isonic. I plan to document my repair to help other newbies that may need it in the future.

I have some questions that some of you may be able to help with, I'm in New Zealand so suppliers/materials may differ from those available in Aus.

1, How can I tell what type of sandwich core (Arex, Corecell, Divinycell ..other) is used?
Starboard say 75kg/m3 density PVC sandwich core.
Can I just use Divinycell H80 (80kg/m3) regardless? (I can get Divinycell locally).

2, Carbon fiber and fiber glass cloth - what do I use?
The Starboard website says it uses "Biaxial T700 flat-laid Carbon 45deg"

If I look off shore I can get 12K T700 45deg (11oz - 380gsm sounds too heavy?)
from www.solarcomposites.com/NewSoller/Carbon-12K-Fabrics.html

Locally I'm limited to plain, twill weave or unidirectional 200gsm carbon.
Does it matter what weave I use? Any recommendations?
Like wise for fiberglass cloth, I assume 4oz (125gsm) E-glass or S-glass is what I should be using, What weave should I use?

I Assume the isonic construction to be something like :
- Core
- 1 x 4oz glass
- Sandwich foam
- 1 or 2 x 200gm/m2 these could be just carbon patches (heels etc.)
- 1 or 2 x 4oz glass

I will know more once I start grinding.

3, For the deck grip, I plan to use UV stable clear EPOXY + caster sugar or intergrip for deck grip.
I can't get boatcoat here in NZ.
I can get a 2:1 mix from www.gemco.net.nz/resins/4-153-GEMREZ-LR-S.
Has anyone had any success with using west system 207 UV clear hardener?
I'm not setup to spray or protect myself from 2 part polyurethane clear coats.

4, Am I correct in assuming I can put clear epoxy over ACRYLIC automotive Paint (blue) from an aerosol can?

5, As I might have to buy so much resin for the deckgrip, I would like to use this for laminating, are there disadvantages in strength to using this clear epoxy (www.gemco.net.nz/resins/4-153-GEMREZ-LR-S.) for laminating against west 105/205?

6, For finishing/sealing the bottom, can I use automotive grey primer spray paint as a top coat and just wet sand it for a smooth finish?

Thanks in advance

SRT

Hi mate.

Surf Sail Australia online for 200gsm carbon and West System. Two stepped lams on the 45ded and 4oz glass over and under..so you can sand without touching the carbon. Lightweight polyester filler over.
Cool with acrylic paint just light rub to get the gloss of with 320g.
foam roller very light coat of resin and sift castor sugar.
careful of expanding Urethane foam it does exotherm and melt foam.
H80pvc is cool. Scarf that in over 40mm if you can..only the original sandwich..you can reshape the new piec after. I route down 4mm then scarf the edges.
hope that helps.

Also inject epoxy but not a lot. Drill every 30mm then go in between with expanding GP6

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Man0verBoard said..
Also inject epoxy but not a lot. Drill every 30mm then go in between with expanding GP6

Two part pour foam works really well to glue broken foam bits together. I have used it to reattach layers and even cut out sections afterwards to see how well it has worked. It seems to really get in and glue the styrofoam together.

I used a lot of 5ml syringes and lots of 4mm holes. One hole to inject into and the other 4 or 6 around it for the excess to leak out. The bonus is that its waterproof, so if you don't care too much, there's no need to add divinycell over the top. Just a layer of glass would do.

I also did a repair where I cut out a damaged section, and used 2 part foam to glue in a block of styrofoam.

The danger is that if you are over zealous with the amount you inject and it has nowhere to go, it can make the board bulge out, so take it easy.

Thanks for the reply(s)

1, Divinycell H80 is all good
2, 200gsm carbon plain weave and 200gsm fiberglass plain weave are to be used
4, Epoxy over ACRYLIC Paint is ok

3, I assume I will need UV stable epoxy for the deck grip...Eg West system 207 UV clear hardener?
Or can I use West Epoxy with 205 (or 206) for the deck grip?

It was mentioned to use Lightweight polyester filler over the glass laminates, I assume an epoxy filler (west mixed 411 or 417) would be ok to use instead?

Cheers

SRT

West 205 and 206 will yellow. It is a yellowish resin anyway so use a UV stable surfboard laminating epoxy for the whole job is best.
Q-cell (microballoons) and same resin for filler.

BTW I am visualising this as say 30cm x 30cm size? Can get away without vac bagging to make it easier.

I agree with 2 pack polyurethane foam for the styro repair. Much better than adding heavy resin (which also may get too hot if you use too much). If the deck laminate comes off easily, often I will inject 2pack foam, then replace the deck laminate with a layer of plastic under it, and tape it on tight. Then when it has cured in half an hour ish, remove deck laminate again and you have a lovely core to laminate onto. (Oh yeah, scrape residual foam off the underside of deck laminate and remove staples first so it is nice and flat)

This is great info and thanks very much.

When you say 'if the deck laminate comes off easily' are you implying you take that off before injecting?
I was going to tape, drill multiple holes in the damaged area and inject 2 part polyurethane before grinding the area back to the styro core + leaving a scarf joint in the sandwich in the process. Having never done this before, I'm open to any suggestions!

I guess I should have asked all these repair questions earlier. I assumed I needed a pump so I now have most of the parts I need for a low flow rate vacuum pump system.....if this is a fail or the pump is too small on my practice board, I will re-evaluate. You are correct, it will be approx 30cm x 30cm..... depending what I find underneath the surface!

^^ Yes I mean taking off a slab of buggered part before injecting (which is not much foam and not very deep, we're only patching up weak styro to get it dead flat again)
I would not vac it for a one time repair. Too easy to apply too much vac. They weight and strength advantages are negligible on a small area on a used board.

Thanks to all that have helped me with this so far.

I ended up using T700 4oz uni carbon which was 12" and super cheap from http://www.sollercomposites.com/NewSoller/UNI.html.

My lay up for the isonic was:
- Core
- 2 part polyurethane foam to fix damage to core
- 1 x 2oz glass
- 3mm Divinycell H80
- 2 x 4oz T700 uni directional carbon @ -45 and 45degrees
- 2 x 4oz glass
-filler, paint, clear epoxy with sifted sugar still to do (but have done this on a practice board.

I've added some photos of my progress on the easiest repair.
The first photo shows the beginning of a 'no vacuum' type repair that Mark suggested to me.....I used waaay to much foam! (Mark did warn me). Then my parts arrived for my vacuum pump so I was keen to try that out for the rest of the repair. Vacuum was set at 7hg to 8hg for the 2oz glass and Divinycell. I started on this, but reduced to 5 to 6hg for final carbon/glass laminate as I was worried that too much resin was being drawn out of the laminate layers. Final result looks ok to me, on to the sanding/filler next.

This is my first go at this. I would be glad to hear if anyone has any improvements I can make!

My next repair will be the crunchy delam between the straps and I'm of two minds weather to cut this section out and add 2-part foam like I did for the above repair or inject 2-part foam through holes and then grind down to the core (I assume that is how the other way is done) any thoughts?

I have also found other deck soft spots on both sides in front of the front foot straps to behind the mast track (this board really is a lemon!), if I push hard down hard (eg similar to performing CPR) I can feel the spots, but they have no crunchy sound so I assume the Divinycell is ok? Should I inject foam and grind back to the core OR inject foam and just add some carbon/glass for added strength on top?

So what do I do with this one then...

Hole is at least 500x500 cracks end 100mm from mast base.

Select to expand quote

berowne said..
So what do I do with this one then...

Hole is at least 500x500 cracks end 100mm from mast base.

Hang it on the wall.

Piece of cake.

By XPS Knauff board from bunnings ($25)
Cut a huge slab to fill all that crap in a big vee shape
Glue it in with minimum epoxy
Shape

Stick the nose in a black garbage bag in the sun for a week to get the XPS foam to off-gas (else you risk some later delam)
|

Glass it up.

Then fix the longitudinal cracks toward mast track.


Or I'll have it an ddo exactly that with it lol

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srtgumbee said..
The used 2014 IS87 carbon I have recently bought turned out to be in structurally in poor condition. Crunchy delam between the straps and under the foot pad of the front strap. I'm sure I can see that resin (or something) has been injected between the straps on right side. The bottom has some pressure dings that have been filled faired out (I knew about these). The owner did not know of the structural issues (it does look great!) and gave me some money back to go towards repairing the board.

So with the help of the board lady website and existing posts on this forum I'm about embark on a repair (Inject foam to fix core, Vacuum sandwich foam + carbon etc and paint etc). I have done minor epoxy repairs in the past, but nothing like this before. I'm going to practice by repairing an old (20years) custom carbon fiber/Divinycell sandwich board, before taking a grinder to the isonic. I plan to document my repair to help other newbies that may need it in the future.

I have some questions that some of you may be able to help with, I'm in New Zealand so suppliers/materials may differ from those available in Aus.

1, How can I tell what type of sandwich core (Arex, Corecell, Divinycell ..other) is used?
Starboard say 75kg/m3 density PVC sandwich core.
Can I just use Divinycell H80 (80kg/m3) regardless? (I can get Divinycell locally).

2, Carbon fiber and fiber glass cloth - what do I use?
The Starboard website says it uses "Biaxial T700 flat-laid Carbon 45deg"

If I look off shore I can get 12K T700 45deg (11oz - 380gsm sounds too heavy?)
from www.solarcomposites.com/NewSoller/Carbon-12K-Fabrics.html

Locally I'm limited to plain, twill weave or unidirectional 200gsm carbon.
Does it matter what weave I use? Any recommendations?
Like wise for fiberglass cloth, I assume 4oz (125gsm) E-glass or S-glass is what I should be using, What weave should I use?

I Assume the isonic construction to be something like :
- Core
- 1 x 4oz glass
- Sandwich foam
- 1 or 2 x 200gm/m2 these could be just carbon patches (heels etc.)
- 1 or 2 x 4oz glass

I will know more once I start grinding.

3, For the deck grip, I plan to use UV stable clear EPOXY + caster sugar or intergrip for deck grip.
I can't get boatcoat here in NZ.
I can get a 2:1 mix from www.gemco.net.nz/resins/4-153-GEMREZ-LR-S.
Has anyone had any success with using west system 207 UV clear hardener?
I'm not setup to spray or protect myself from 2 part polyurethane clear coats.

4, Am I correct in assuming I can put clear epoxy over ACRYLIC automotive Paint (blue) from an aerosol can?

5, As I might have to buy so much resin for the deckgrip, I would like to use this for laminating, are there disadvantages in strength to using this clear epoxy (www.gemco.net.nz/resins/4-153-GEMREZ-LR-S.) for laminating against west 105/205?

6, For finishing/sealing the bottom, can I use automotive grey primer spray paint as a top coat and just wet sand it for a smooth finish?

Thanks in advance

SRT

Or you can buy my 2015 97 iSonic that I've got advertised on the buy/sell In mint condition.

Thanks, but I'm having fun learning how to fix this board.

The irony of my situation is my 2005 Carbon art SL55 truly is in mint condition, but has lost its grip. This seemed difficult to do nicely and the board was old so I bought the isonic87 (which had no soft spots according the owner). Now I'm researching, injecting foam, grinding, vacuuming, laminating, filling and sanding, painting.....oh and then adding grip!

For a crunchy delam repair and drilling lots of holes before injecting 2 part foam, do you then grind/sand back the damaged area to the EPS core OR cut the area out to get to the EPS core?

One other question: For those that have a vacuum pump and use it to apply the glass + Divinycell layer, do you also use the pump to apply the glass/carbon laminate?

I cut out a 30cm x 40cm slab between the straps and found Dcell stuffed on left hand side as well as some minor EPS damage.
Epoxy had been injected on right hand side and there was an exotherm hole in the EPS at the bottom of the injection point, this would have not lasted long!
Found the creaking noise to be a staple moving in/out when deck was flexed.

I will now add 2-part foam then fix it in the same way as the previous damaged area.

After getting the Dcell down and getting ready for the top laminate, I discovered soft spots in front of the straps (if I pushed firmly with the palm of my hand). I didn't know how far to go to cut out these soft spots out so I injected foam and went exploring with the sander.
Found cracks in the internal fiberglass layer , followed the cracks until they ended.

I then added new Dcell on and decided I would apply a top laminate to the entire back of the board. I could have laminated without a vacuum bag, but as I had the materials and not much experience with laminating, I decided to use bagging method. This would ensure I had the minimum amount of resin.

Each carbon layer weighed 70grams (2 layers used) and each 4oz cloth layer weighed 53grams (2 layers used). I got 4 x 100mls of epoxy resin + hardener ready to be mixed and I was working with only 100mls at a time and thus reducing problems with the 10min pot life.

I had issues applying the epoxy over the carbon fibre.... it runs off the carbon so fast, quite different to glass cloth. So a lot of my first pour ended up going beyond my desired 'repair patch'. After that I got used to the runny resin and it became easier to apply. My vacuum bag had resin along its sealing tape and some of it got vacuumed into small ridges that I had to sand back once epoxy had set.

Some epoxy + Qcell was used to fill in the low spots and then it was painted with SCA acrylic paint from super cheap

The bottom was sprayed using a can of SCA primer followed with SCA clear coat. Then sanded with wet 600 grade sand paper.

The white was sanded back and I was trying for the 'pro' sanded look, but my black carbon + white filler pattern was coming through so I stopped before this became obvious. This board is for me and knew it wasn't ever going to look good . Pads glued back on with selleys kwik grip. I rolled UV epoxy on top and applied caster sugar. This worked really well and I love it under my feet.

My 'cheap as beer' vacuum system.
The pump used was this: www.sparkfun.com/products/10398 . This pump can pull 15"hg if you want it to, airflow is very low though!
PVC pipe was lying around, all other parts where cheap from china (ebay). A $3 ebay map sensor was used to detect pressure and give me a voltage so my microprocessor could turn on/off the pump with a 1"hg hysteresis. The pressure range I chose was 6 to 10" hg and this was selected using a knob pot. The pump has very low air flow but the PVC pipe helped by allowing me to quickly suck down the vacuum bag areas of my repair.

Thanks heaps to those who have helped me on this journey.
The board came out at 6.65Kg with straps on and this was 500grams heavier than it was before the repair. It feels and sounds solid now and I'm stoked to have got this far and have learned heaps in the process.

Extra bonus was on its maiden voyage, matched with my KA 6.6, I got it going 2knots faster in chop than my previous slalom board

Select to expand quote

berowne said..
So what do I do with this one then...

Hole is at least 500x500 cracks end 100mm from mast base.

The Tip.

Select to expand quote

gavnwend said..

berowne said..
So what do I do with this one then...

Hole is at least 500x500 cracks end 100mm from mast base.

The Tip.

Cut the nose, it's not touching the water when you're foiling anyway.

Fantastic job, should be proud of yourself!!

Good stuff , nice fix
If only they used another 200 gm of resin from mast track back on the first layup , this would probably not happen.
Long live over engineering !