I'm about to undertake my first serious DIY repair and have used the following video posted by Paul van Bellen for inspiration.



I've sustained a number of hits on the front of my windfoil board and have so far been covering up the cracks with squeeze out of the tube epoxy. I've now gone out and bought all the gear mentioned in the video (Westsystem expoyx, qcell, fiberglass cloth, primer filler, spraty putty, etc.) and ready to take the plunge.

I've covered the board with masking tape and sanded the cracked areas with 80 sandpaper. What I've noticed is that there are different levels of damage and I'm not sure if if all merit the full fiberglass + epoxy + qcell treatment

In below pics:
Pic 2 - this is the worse damage, my plan is to follow the steps in the video
Pic 5 - 2nd most concerning damage, Is the black stuff the carbon layer? Should I sand down more to create a V and then apply steps in video?
Pic 4 - I'm on the fence about what to do here. Can/should I get away with something simpler (adding only epoxy or just painting for example)

My questions:

1) Not that I'm seeking perfection but in order to avoid a lumpy finish is it advisable to sand down the surface to "make room" (V shape into the board) for the new fiberglass/exoxy/qcell. In other words should one inflict more damage to the board in order to come out with a smoother finish?

2) Given the extent of the damage, should I simply just apply one long strip of fiberglass from one side of the nose the other. Any pros/cons to doing this. Hoping this might help avoid a lumpy looking finish.

3) What does the spray putty do exactly and why in the video is it applied after the primer filler? Should one ever apply the spray putty first?

4) The video didn't really show the painting stage. What tricks does one use to ensure as clean/straight lines on the paint. I've got masking tape on there but would be surprised if that will do the job.

Thanks in advance for any advice.

Pic 1


Pic 2


Pic 3

Pic 4


Pic 5

I've used solar res and works ok for certain repairs
I have watched the video when it came out thinking that was really well done by both Mark and Paul and haven't watched it since, as years ago built epoxy sandwich boards and repaired them and there are variations of steps, so don't get worried about following to the letter.
The basics are sand more paint off for better adhesive of resin fiber mix on surface, the glass (or Carbon or mix - layered) to be wet out without excess resin is the key to strong watertight repair. The filler coat or bog and paint is fair to in the patches and make it look good.
It's a great skill to have when owning a board

If I'd do this repair, I would indeed dig deeper, as you suggest. But more importantly, I would extend the area to go past any cracks that can be seen in the fiberglass. In your pic 2, that would mean going all the way to where the tape is. In pic 4, the crack seems to go at least to the tape, so I'd remove some of the tape. Maybe that seems like overkill, but I have seen repairs that were too small, and needed to be re-done a while later.
I'd also use 2 layers of fiberglass, so I don't have to worry about sanding down a bit too much. If I wanted to reinforce the nose to make future similar damage more likely, I'd certainly consider 3 layers, and use large strips that cover the entire nose at least to where your tape starts. The extra weight is minimal and outweighs not having to do repairs again.

Is the damaged area soft when squeezed. You want to inject foam if so.

Then you sand down below level as you'll be adding layers of fiberglass and resin. You'll sand down then use filler, sand again and paint.

boardlady.com/repairbasics.htm

I am no expert by any means, but it looks like you finally got a nose pad to install, so I would sand down the whole front nose edge and put a strip of fiberglass across it all to unify the separate repairs, then install the nose guard and not worry about something opening up later.

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Manuel7 said..
Is the damaged area soft when squeezed. You want to inject foam if so.

Then you sand down below level as you'll be adding layers of fiberglass and resin. You'll sand down then use filler, sand again and paint.

Thanks Manuel7.

The surface isn't soft but when I squeeze the board in the area of Pic 2 there is a little bit of movement (I can compress the sandwich slightly and then when I let go it pops up again).

Having to insert foam sounds like a new rabbit hole I'm uncertain I'm ready to go down so keen to avoid if possible.

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Manuel7 said..
Is the damaged area soft when squeezed. You want to inject foam if so.

No need for this on the nose, nor is the any really need to rebuild the sandwich, in that isolated area. The goals are to make it watertight, and maintain the rest of the integrity of board. i.e not let it delaminate where it really matters. Instead of rebuilding the sandwich which really requires a vacuum bag, you can either just rebuild the top layer of the laminate as the video that mark posted does. Or when the crack is bad and the high density foam has cracked, I sometimes cut out the high density foam, and the shove wetted out glass under the existing laminate, and the pack it out with more glass or carbon until the hole is filled. This will maintain the original strength of the board on the deck and bottom.

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cleverku said..

The surface isn't soft but when I squeeze the board in the area of Pic 2 there is a little bit of movement (I can compress the sandwich slightly and then when I let go it pops up again).

Your not really compressing the sandwich, when the top layer of the sandwich cracks, so does the bottom layer. So the whole pieces is now free to move, your compressing the EPS underneath. It is the bottom layer that resists your pushing as the fibres work best in tension. A proper repair of high stress areas need the laminate to be rebuilt. e.g. deck area where your feet are etc. This is NOT what you need to do here.

Also keep in mind that fibre and the top looks like carbon and kevlar weave. The kevlar is there for impact strength, but it is painful to sand.

Agreed. Stop overthinking it. Sand all the paint off the nose. Then 3 layers of 4 oz over the whole lot, make them progressively bigger to save on filler

Fill over with resin and q-cells, or auto bog

Sand.

Then watch the painting video.


(For any continuing unbelievers on nose softness - like the whingers on Yoochoob - if it is a little soft around the crack, that's natural and you don't need to go nuts rebuilding the sandwich. In the middle of the board you would, as its highly stressed. Heel dents, you would. Etc.
However the nose is not stressed at all. You can glass over soft (ish) bits. Think about it....... Spend days cutting out large areas, reshaping styro, heat forming PVC foam, vac bagging it on, blending it out, then glass and carbon and fill and paint. Etc. Then the rounded, small diameter, very hard mast hits it again at 60kph. Will it fare any better than the above nose with 3 layers of glass over? Nope.

If it's not soft and you've removed all the loose stuff then glass over. You first start with a small piece of glass (right over the damage) then go larger and larger. No need to go crazy just a bit beyond the damaged area. Try and squeeze the resin out of the glass so you use the least amount.

I've had to repair my boards nearly daily when learning forwards. It helps to try on both tacks to distribute the load evenly !!!

Thanks all for all the great advice. I finally took the plunge today and applied the fiberglass and epoxy to the sanded nose section. It's all dried now after about 3 hours and for the most part I'm happy with it. The area of concern though is the area which had the most damage (down to the exposed sandwich). When I push down on this section it's not solid like everywhere else on the board, it sort of squishes down like there's a gap between the sandwich and the fiberglass I've applied.

Have I buggered this up or will the qcell harden this up?

I'm not after perfection but the squishy feel doesn't seem right. Any advice appreciated.

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cleverku said..
Thanks all for all the great advice. I finally took the plunge today and applied the fiberglass and epoxy to the sanded nose section. It's all dried now after about 3 hours and for the most part I'm happy with it. The area of concern though is the area which had the most damage (down to the exposed sandwich). When I push down on this section it's not solid like everywhere else on the board, it sort of squishes down like there's a gap between the sandwich and the fiberglass I've applied.

Have I buggered this up or will the qcell harden this up?

I'm not after perfection but the squishy feel doesn't seem right. Any advice appreciated.

Nice job . That's the great thing about DIY. If you're not happy with it, you can scrap it off and start again.

I would leave the outside as it is. Buy a 5, 10, 20ml (whatever's cheapest) syringe at a Chemist, and drill a few 4mm holes along your rework. Fill the syringe (with 4ml nozzle) with epoxy and inject about 1-2ml in each hole (make sure you tape the board up, this can get messy noting that the epoxy may be under pressure when you pull the syringe out. It takes a bit of knack). Then put some masking tape over it. Once it's cured, clean job up as usual.

Just out of curiosity: What exact resin did you use? Mine will not be hardened in 3h. Maybe it is not sticky anymore, but it will take 24-48h to harden. Better leave it as ist is and wait.

If it's not hard by the next morning , chuck another couple layers of glass over the soft area .
If it's still not stiff , something is wrong . Even if it's hollow underneath, it should be solid .
If after that it is still soft , it's a resin malfunction problem .

as said, epoxy takes a while to harden after 3 hours that will still be very soft.
That area does look a little low, some smaller lengths of cloth over that gap in the sandwich, to bring the level up to the rest of the rail will help a great deal.

Quick update on this. As many suggested the epoxy just needed a bit more time to set. It's pretty solid now that I've given it 24 hours. Though feeling firm to the touch, the area in question does make a different sound when tapped. Not sure how to describe, more of a higher pitched "tapetty" sound than a lower pitched "donk" sound. I'm inclined just to leave it as is and move on to the next steps, I'll likely need to fix it up again soon following my first catapult anyways. On reflection I think the error I made was to apply a large piece of fiberglass to the nose rather than start small and build from there.

Hopefully smooth sailing from here on. I'll make sure to post pictures of the finished product to seek praise and admiration

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cleverku said..
On reflection I think the error I made was to apply a large piece of fiberglass to the nose rather than start small and build from there.

Hopefully smooth sailing from here on. I'll make sure to post pictures of the finished product to seek praise and admiration

I remember reading online that Boeing and Airbus have opposing views on how to feather in, in their case, carbon fiber for a repair. I don't recall which was which but one recommends starting with small pieces and building to bigger pieces and the other just the opposite. ie don't worry too much about this.

Edit: mansbergeraircraft.com/Aircraft Composite Repair Design Paper.pdf page 5

"Two different methods of scarf joint lay-ups are currently being used. In general,
military specifications and Boeing use a lay-up starting with the smallest ply down first and
building up to the largest ply last on the outside. Airbus and many European aircraft
manufactures use a reverse method and start with the largest ply down first and the smallest ply
on last. In the Airbus method the orientation of the laminate schedule must be reversed and the
lay-up becomes a mirror image of the original skin. "

The most important is that it's water tight. If it cracks from stress you can revise later. Just keep an eye on it.
This is where lighter colored boards make it easier to spot cracks.

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cleverku said..
Quick update on this. As many suggested the epoxy just needed a bit more time to set. It's pretty solid now that I've given it 24 hours. Though feeling firm to the touch, the area in question does make a different sound when tapped. Not sure how to describe, more of a higher pitched "tapetty" sound than a lower pitched "donk" sound. I'm inclined just to leave it as is and move on to the next steps, I'll likely need to fix it up again soon following my first catapult anyways. On reflection I think the error I made was to apply a large piece of fiberglass to the nose rather than start small and build from there.

Hopefully smooth sailing from here on. I'll make sure to post pictures of the finished product to seek praise and admiration

What you are saying then is that the repair does not sound "hollow" like the rest of the board, I think. In my experience, that is common because the repairs I make tend to have a little bit more layers than the original layup.

As promised here are some pics of the final product. I have to say I am quite blown away with how well this turned out. Always just assumed my first attempt would end up looking a bit of a Frankenstein.

Thanks to all for the advice provided. Particular thanks to Paul and Mark for making that video and inspiring me to take on this challenge. As someone who doesn't consider themselves handy this has been a really rewarding experience.

Small notes to self for next time:
- I think I'll use blade putty instead spray putty next time. The spray putty I got from super cheap auto didn't seem to achieve much (didn't fill in the pin holes or paint chip indentation I assumed it would)
- I'll make sure to put the f*$%ng vent plug back in before I hose the board down. Can't believe I can be such an idiot.

looks great! Now you'll be really upset next time the mast/boom crashes into it.
My thoughts on a tapered build up.
I normally aim to put on more cloth than needed, so the outer layers will get sanded back. so it's better these layers are the short ones, other wise you'll loose tension strength when the full length fibres get sanded away.

Then of course, if you're filling in a valley, fibres across the valley will be pulled up under a tension strain. So there are reasons for doing it both ways, for best tension strength the fibres need to be at least straight or better, convex. So I'd start the base of the valley with short lengths, then use full lenghts approaching the surface level.

So I've made arguments for both cases, maybe go for a hybrid

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cleverku said..
As promised here are some pics of the final product. I have to say I am quite blown away with how well this turned out. Always just assumed my first attempt would end up looking a bit of a Frankenstein.

Thanks to all for the advice provided. Particular thanks to Paul and Mark for making that video and inspiring me to take on this challenge. As someone who doesn't consider themselves handy this has been a really rewarding experience.

Small notes to self for next time:
- I think I'll use blade putty instead spray putty next time. The spray putty I got from super cheap auto didn't seem to achieve much (didn't fill in the pin holes or paint chip indentation I assumed it would)
- I'll make sure to put the f*$%ng vent plug back in before I hose the board down. Can't believe I can be such an idiot.

Looks great Cleverku well done!