Isonic repair materials?

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

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

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

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!

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!

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

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

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

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!

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?

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.

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

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.

Fantastic job, should be proud of yourself!!