bgytr

injectadeck or similar?

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Has anyone used injectadeck or a similar injection method for fixing bad deck cores?

The seemingly preferred solution is to cut the top deck skin off, replace the bad core, then reglass the deck back in place.  My concern with that method is the joint seam when glassing the deck back.  If the transverse seam is not scarfed in well, it will be a weak spot when the hull bends from rig loads.  In addition to likely developing a crack, it could also be a long term structural issue.  But if done right, it could be good as new.

Injection techniques seem interesting, but I'm wondering if there's anyone here who might vouch for the technique.  It could be better to not introduce large cuts in the structural glass, although you will get a stress concentration factor of 3 around each hole from in plane stress.  As long as there is enough of a bond to prevent local buckling from in plane compression, and enough rigidity in the foam to eliminate the spongy-ness, it seems like it could work.

Anyone used these techniques? 

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I am very interested in responses. I just purchased injectadeck to seal up some rot in my transom. 

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I had a boat once with balsa cored deck The prior owner attempted a fix like the above photo.  It was a small area, maybe a 1' diameter circle. He drilled about 8 holes and filled with epoxy. Not sure what type or if any drying involved. The deck was rock solid in the area of the repair. But a hairline crack developed around the exterior of the repair. It was in a high traffic area on the deck. I always assumed it was from the different core materials. The epoxy was solid and the balsa might flex a little.

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Injection for core repair is wishful thinking.

It doesn't work.

I speak from experience.

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49 minutes ago, SailMoore1 said:

I had a boat once with balsa cored deck The prior owner attempted a fix like the above photo.  It was a small area, maybe a 1' diameter circle. He drilled about 8 holes and filled with epoxy. Not sure what type or if any drying involved. The deck was rock solid in the area of the repair. But a hairline crack developed around the exterior of the repair. It was in a high traffic area on the deck. I always assumed it was from the different core materials. The epoxy was solid and the balsa might flex a little.

 ya I can see that with the epoxy being hard spots.  I  wonder if the injected structural foam might be more pliable and thus reduce the tendency for cracking.

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47 minutes ago, SloopJonB said:

Injection for core repair is wishful thinking.

It doesn't work.

I speak from experience.

what material did you inject and what problems did you have?

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Epoxy. Problems were basically what caused the delam in the firs place - water intrusion.

I tried all the usual methods of drying core - vacuum, compressed air, drilling patterns of holes & leaving it in the sun, you name it.

Trust me, it doesn't work.

The only way to repair bad core is to cut the deck open and replace the bad core.

The only situation I can imagine injection working would be some dry delam from improper construction. If it's wet it simply won't work.

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I did it in a small area around a stanchion.  Dried out in hot summer sun for a couple of months first.

Somewhere on here is a (Ranger 28?) Rehab thread where the owner did an entire side deck.  Sounded like it ended up being more work than simply opening the deck and re-coring.  

 

Edit: I meant I did that sort of repair with epoxy.  Not the two-part polyurethane shown on that web site.  Interesting idea, but I don't think I'd buy from that site. I have been intending to buy some for ice box insulation.  Injecting foam into small places is always a minor disaster to begin with... Still I've done it a little bit in the void between hull and liner when installing ports and hatches.  

I'd like to see them tear open a deck after that repair and demonstrate where the foam went.  

Edited by toddster

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1 hour ago, toddster said:

I'd like to see them tear open a deck after that repair and demonstrate where the foam went.  

Yes. 

Just speculating here - even when balsa has turned to soup, it's not all going to drain out - there could be many areas where the balsa is severely compromised but not turned to soup yet. There needs to be accessible voids for this stuff to work, and without removing the skins, you may never really know where there are and are not voids.  To remove decayed balsa to create a sufficient volume of voids for this stuff to work may end up requiring a lot of effort. 

On the other hand, my main concern would be the bond between the new "core" and the skins.   More precisely, there needs to be significant interlaminar shear strength at that point  or you defeat the whole purpose of a cored laminate.  One of the main problems is obtaining a clean bonding surface on the inner sides of the skins.

Now...IF (and it's a big if in my mind) the product acts as claimed: "epoxies cannot stick to wet dirty surfaces like water catalytic injectadeck" , then maybe this product just might work, in certain instances.  It might tap out okay, but I would sill be concerned about the bond.

 

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3 hours ago, 12 metre said:

Yes. 

Just speculating here - even when balsa has turned to soup, it's not all going to drain out - there could be many areas where the balsa is severely compromised but not turned to soup yet. There needs to be accessible voids for this stuff to work, and without removing the skins, you may never really know where there are and are not voids.  To remove decayed balsa to create a sufficient volume of voids for this stuff to work may end up requiring a lot of effort. 

On the other hand, my main concern would be the bond between the new "core" and the skins.   More precisely, there needs to be significant interlaminar shear strength at that point  or you defeat the whole purpose of a cored laminate.  One of the main problems is obtaining a clean bonding surface on the inner sides of the skins.

Now...IF (and it's a big if in my mind) the product acts as claimed: "epoxies cannot stick to wet dirty surfaces like water catalytic injectadeck" , then maybe this product just might work, in certain instances.  It might tap out okay, but I would sill be concerned about the bond.

 

It depends on the span if core shear is necessary.  Ya for a long span where you get bending behavior, you need a good bond for the length of the span.  If it's a small soft spot with short spans, you're probably ok.

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Unless your boat is built to really tight structural margins, so much so that your deck would fail after a delamination, then any proper repair will not weaken the structure. Like others have said, injecting resin isn't a good fix. Cut the delam out, laminate the border, bond in a new core, add new outer skin.

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I think it depends on the core and the laminate thickness. There will always be some rotten material left around the edges. Some materials will quarantine the rot and it won’t spread and others will. For my boat the balsa core rotted around deck fittings but doesn’t seems to extend further once you remove the source of the leak. For small areas it worked well and after several years is still solid.

 

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On 2/27/2019 at 8:21 AM, bgytr said:

If the transverse seam is not scarfed in well ...

Then fuckin scarf it in well

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I have successfully used the swiss cheese method on a part of my balsa deck.  The trick was to use large enough holes that you can really see inside and make sure you have the glass completely cleaned up, and to go far enough that you are definitely getting to solid core around the edges.  I also filled with a West epoxy mix with a lot of filler in it - the theory being that extra filler will make the repair able to flex slightly and avoid the cracking mentioned above.

The only thing that didn't work well is that the exposed epoxy filler in the holes shows a little through the new gelcoat non-skid on top of it, so you can see where the swiss cheese holes were.

This was also a small circular area, perhaps 30 cm in diameter.  I wouldn't try this on a large area - I'd suggest going back to cutting away the deck in sections, replacing the core with same and then glassing the deck back in.  I would suggest making the deck cuts inside the edges of the non-skid so all you have to do is re-apply the non-skid when it is done to cover the repair.

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5 hours ago, fucket said:

Then fuckin scarf it in well

that can be difficult to near impossible with a thin skin cored composite.  There's often not enough thickness to develop enough of a scarf to get a good connection, especially in a transverse cut. 

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We had problems with delamination in the cabin top. Essentially everything under the handrails - areas about 18" x 72" on one side and about 10" x 48" on the other.  We attacked from underneath, so no troubles with deck structure or recreating the nonskid pattern. Cut out the overhead & removed all rotted balsa & let any other areas dry out. Then replaced w/new balsa core & fiberglass w/polyester resin.  (Didn't want to create hard spots or "edges" in an area that large by using epoxy.) Took several weekends of work.  Then had the overhead shot w/gelcoat to match existing.  Shooting epoxy into the core is, by definition, hit or miss.  Unless you stop the water getting into the deck, problems are going to continue.   

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I have fixed  y injecting Gorilla Glue. Because it is ureathane it cures in contact with moisture. Because it foams, it fills the voids.  I don’t have 25 year data, but it seems to have done the trick. If it doesn’t hold up, you make the Proper job of it later.

SHC

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On 3/1/2019 at 4:03 AM, bgytr said:

that can be difficult to near impossible with a thin skin cored composite.  There's often not enough thickness to develop enough of a scarf to get a good connection, especially in a transverse cut. 

Partially true, partially not. I'm speaking from experience, having repaired highly loaded composite structures with 30gsm (yes, sub 1oz/yd^2) skins. Fortunately the skin isn't loaded beyond the limits of the material but the spar often is. At some point you accept a small (<0.010") bump where the new laminate scarfs over the old laminate. With some compression added to the repair you can make this nearly invisible; I'm OCD as hell so can spot it under the right lighting but I would rather have that overlay vs. a straight butt joint with no overlay. Most boats have enough gelcoat/paint thickness to accommodate this during finishing work to boot..

Steve C., that is interesting and makes perfect sense. What time frame has the repair held up under, 1+ years?

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One year and counting.

Its an A cat.   So consequences are minimal.

SHC

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      if the leak isn't fixed , the surrounding areas will continue to rot and the problem will get worse

the above method is you end up with a multitude of  hard little pillars  surround by saturated rotting junk and then you have to fair in the deck to get rid of all the divots..

 

trying voodoo fixes  only makes the last fix harder..

 

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If balsa core that has gone squishy I doubt anything except proper repair (remove, replace, replace laminate) would work.

Injecting decks is pretty common on Hobie 18s (foam core). I did it on my ex-Hobie 18 and the repair held up great for years. I used West epoxy in small bottles to inject into a grid of holes drilled into just the top laminate. Took way more glue than I anticipated, but once it was done that deck was solid as a rock for years.

 

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