I purchased a partially delaminated bamboo Naish Mana for cheap. I thought it would be a fun project but am learning the intricacies of repairing laminate construction boards and greatly appreciate input.
I have cut out the delaminated section to expose the EPS. I have also sanded down the ding. The rest of the board is in great shape.
I have received/entertained different ideas including:
Use pourable foam to rebuild the volume and glass/laminate
Put a piece of 1/8 inch 3 lb/cu ft divinicell in there with vacuum after sanding EPS flat. Vacuum it in place, fit gaps with pourable urethane foam. Glass over.
I am looking for durability (board for kids) over keeping it super light.
Any other thoughts here appreciated. I don’t have a vacuum setup, but will pay someone locally to help me.
Level it our the best you can - sand it flat after cures.
Laminate 2 layers 4 oz or 6 oz (or combo - up to you) with yellow pigement, extend the patch 12" onto bottom and over the rail to cover that rail ding.
Fair the fiberglass edges into the bottom and rail, hotcoat, sand.
was the delam section that you cut out div.cell? I would replace like for like. Also get rid of that straight cut and angle the cuts so that your replacement section is a diamond shape. Also grind a angle into the edges of the skin (up at least an inch) so the repair can ‘scarf’ into the existing structure.
having different constructions or horizontal cuts will create a hinge.
The inside is EPS. The laminate was glass, wood (I think bamboo), then glass over the EPS. I wasn’t going to do wood laminate, but if I can find it maybe. It certainly is stronger to have those laminates (for puncture etc).
I was just thinking of using the divinycell as the filler for the EPS foam for a little extra strength(as opposed to the microballoons/epoxy, but your hinge thought makes sense). They have a 1/8 H60 mat that has little grooves in it so it fits curves. The actual delam was not at the glass/EPS layer, but within the EPS so it took up ~ 1/8 inch-1/4 inch of the foam when I peeled it back.
I will round out the cut as you specify.
I was also planning on feathering the glass over the rails to the top (ending at the end of the white so don’t have to mess with the nice bamboo section).
Thank You again for all your suggestions. Amazing amount of expertise here.
I have filled the defect with 3lb 2 part polyurethane foam then sanded it down flush to the level of the existing undamaged section. There is ~ 1/4 inch of the PU foam over the EPS, resulting with it flush to the level of the outside of the board(outside the glass). I will post pics when I get a chance.
I think I have two options.
Sand it down a little more and then put down a layer of glass, layer of 1/8 or 1/4 divinycell with vacuum($20-30), sand to make bottom shape smooth and consistent, then glass on top with bag.
Sand down only the thickness of the current glass/bamboo/glass layer (1/32-1/16 inch thick) and then then laminate just glass, or try to find a verneer to sandwich in between, all in one step more like a new board would be done. This would be most like the initial structure, but verneer is expensive ($80 plus shipping unless I can find local) and I am going to paint over anyway.
In either case I will wrap the glass onto the rails, but not the verneer or divinycell.
I was trying to mirror this, but the board in this example is a glass/foam/carbon sandwich, I don’t have as much “thickness” to my skin over the EPS, which makes it harder in some ways. Hence my question above.
Here’s the easy way: Fill the exposed section with layers of 8 oz cloth and it will take a lot to level it. Cut it right to the edge of the openings while wet. Sand the edges of the inset cloth around the perimeter and fill any irregularities. Laminate a fabric to hide the mess, then a very large 4/4 or 4/6 clear wrap. Then sell the heavy thing. You probably know why this happened in the first place, and a delam this big will have the glass/foam bond weakened over the whole board. Even if vented, this may happen someplace else or right next to what you just did due to the weak bond. The effort and cost will get very close to glassing a new blank (or this one stripped). Once a board is blown up like a balloon then just repaired in the gross sections, well it just isn’t something I would keep.
Your many layers of glass idea has many merits, as does your comment it may delam right next to where I repair it. The local respected shaper listed on surftech repair site passed on repairing it for the reasons you specified.
I agree this is not an economically smart project (materials and tools cost as much as just getting a used demo board at end of season).
If I had to do it again I probably would have passed on the board, but I have already started and am using it as learning experience rather than any high expectations for longevity or performance.
That said I want to do the best I can and learn some skills (get some tools) for when it matters more on a more reasonable repair. In the future I would love to build a real board.
I am going to try to recreate the shape and strength like the board lady, but do not expect her quality of result.
I use the glass layering technique on poly delam’s also, but the best way with epoxy is to 2 step bag it (1/4" D-cell first, smooth it out, larger clear lamination second). Fixing delam’s is always a lost cause, no matter what kind of board. Get some kind of vent in your project before you use it, maybe two of them.
Brian or Pete’s method will work just fine. I’ve even used spackle to fill the beads and smooth the foam surface. Then a layer cut wet right to the edge. Another layer or layers to bring it up flush and overlapped. Hot coat and sand. Then fair it with the one part body filler, filling pin holes etc. Prime and paint to match. Clear coat if needed. If it had a veneer under the glass and you can get ahold of some I would glue or bag that onto the foam then glass and fair. Going back with what came off is always the best bet. You don’t need to inject anything into the foam on that ding. Just fill it and glass over it. Fair prime and paint to match. Fixed lots of Surftechs,Boardworks and Naish boards using this method.
I had started with the board lady method of the 3lb PU 2 part foam to recreate the bottom shape and smooth the EPS. Left with big bumpy mess initially on top of EPS, but sands down nicely and is quite rigid. Downside is a couple places I didn’t mix the foam well enough and the foam is not as high quality. (Any fast mixing methods appreciated!). Might try a drill with a stick but you literaly only have ~ 15 seconds.
I have cut our the bad spots and will repour there and sand down. Crushed foam underneath rail also injected with the PU and now rigid, not compressible.
I got H45 1/8 and 1/4 inch divinycell sheet in the mail last night (my original plan) to layer up on top of the EPS(sounds like would have worked as above). I think I will do glass, D cell, then sand to almost finished shape, then glass/veneer/glass. If I can do the PU foam layer nice enough I could do PU, glass/verneer/glass, but I am not sure I trust the PU. Maybe if I knew how to pour it better.
Yes, Casica Goretex vent ordered, although it might not save it. It is just a 9 ft x 30 in SUP so I am thinking one will do it.
I basically made the PU foam flush with where I want it to be so probably won’t need the D cell. Thinking glass, wood, glass.
Bamboo sheet large enough seems quite expensive ($150 for 4’x 8’’ locally or $100 shipped online). Any cheaper options? I want something ~ the same thickness as the bamboo layer which is probably 1/40 or so.
Was looking at Corecork in 1 mm and splicing it into the bamboo? Would another wood listed here work? Gonna get painted anyway.
If you’re just going to paint it anyway then you might as well stick with FG. I think laying layers in different directions improves the strength characteristics.
I’d also route in a couple of mini-stringers to bolster the core at the break before glassing. Paint sticks are cheap and easy. 2-4 per side, offset from the stringer and each other. If the board breaks again it won’t be at the original break.
Thank You. There was no break, it was a delam only, but it pulled up ~ 1/4 inch of the EPS, which is why I used the PU foam to recreate the bottom shape.
Am I going to lose impact resistance without wood sandwich? That was my concern.
The wood is basically a lighter replacement for an equivalent thickness of fiberglass/resin. When used as a small repair panel the impact resistance is similar, albeit at a lighter weight. The stuff definitely dents and dings under impact when the force involved is that significant.
I have used veneer for replacing bad deck delams, but I mostly did it to save a little weight and to cover my patching efforts below, and in lieu of painting. On a small deck patch the weight we’re talking about isn’t that much - it’s nothing like the weight savings of doing veneers on both sides of an SUP or longboard.
I guess what I’m saying is that if you already had some veneer scraps from other projects onhand then bagging a deckpatch on doesn’t really cost anything. If this repair requires the purchase of a new 4x8 veneer panel and you’re only going to use a 2x2 piece of it in order to save a few ounces of weight on your repair then that doesn’t seem like a great bargain at all.
If you really want to do a veneer patch for cheap, try ordering a couple smaller pieces from CertainlyWood.com. They sell an 18" x 96" panel of bamboo veneer for $20 plus shipping. You’ll have enough left over to do a couple deckpatches. They’ve got a 19.5 square foor piece of Ash veneer on sale right now that would work great for your repair - price is $12.35 + shipping costs. Cut-n-paste to get your deckpatch.
Don’t spend $120 on a 4x8 piece of bamboo for a simple repair. I can get those panels locally here in SoCal for $55 on a will-call basis.
The best way to fix an issue with any SUP is as follows:
Take a it to a safe and open area away from dogs and children.
Pour and entire gallong of premium gasoline over it
Strike a match and carfeully place it in the exact center of the SUP
Say a prayer to Buzzy Trent using these words “Makaha” and “Marylin Monroe”
Wait until the SUP is a pile of black dust
Man up and denounce Satan, Laird, and the global-surf-industrial-complex
Look at the pretty flowers, smiling children, cute little dogs, chirping birds, and the sunshine on the ocean, and breathe a sigh of relief that the darkness is a thing of the past
Yours is is a rather soulful approach to the problem. with a slight hint of “Point Break”, but given the level of expertise and knowledge on Swaylock’s perhaps we could get more creative.
Maybe drill multiple small holes and fill with nitroglycerin, to create sequenced explosions to carve it into a cutout of “insert most hated global surf industry” synchronized to music, finishing with a final finale of EPS confetti?
Other suggestions of course welcome.
In all seriousness, learning quite a bit from this. The pourable 3 lb PU to recreate the bottom worked pretty well, it really sticks to the EPS and is quite light, but tougher than the EPS.
Waiting for my Gast 704 and then will try next steps.
