Replacing wet balsa core

[minaret]

Yeah, you got this. Burning the midnight oil and everything.


What'd you glass with?

[Scott Fuller]

Originally Posted by minaret

Yeah, you got this. Burning the midnight oil and everything.


What'd you glass with?

I used West Systems cuz I'm just a hack and it's easy not to screw up! Three layers of 1708, now I've got the fairing to look forward to.

You joke about the midnight oil, but here is Wisconsin when I did my layups the temps were in the upper 40's to 50's during the day but much colder at night, so I spent a couple of nights on the boat in the yard so I could keep some heat going to make sure I got a good cure!

Scott

[minaret]

Originally Posted by Scott Fuller

I used West Systems cuz I'm just a hack and it's easy not to screw up! Three layers of 1708, now I've got the fairing to look forward to.

You joke about the midnight oil, but here is Wisconsin when I did my layups the temps were in the upper 40's to 50's during the day but much colder at night, so I spent a couple of nights on the boat in the yard so I could keep some heat going to make sure I got a good cure!

Scott

Should be fine with epoxy, since it's all in non skid and thus can be finished in primer and paint with no blends. A little forethought saves a ton of labor later.

[BigSmile]

Originally Posted by minaret

To answer both questions at once:

If you add laminate to the top side of the inner skin, it will throw of your core thickness. That is, if you have 3/4" core which you have removed, and you replace it with 1/16 of glass + 3/4" core, your core will sit 1/16" higher than the surrounding core. If you rebond the top skin this way, the whole deck repair will be high by this amount. High is bad; it is relatively easy to add material and fair in a low, but it is much harder to fair in a high, as material cannot be removed without taking out part of the upper skin. Therefore, if the inner skin is damaged in the core removal process(common), you must either repair it from underneath if possible, or back grind it, glass it, and rough fair it from the top, to avoid high spots in your repair.


Don't get carried away, though. Just the act of bonding in Coosa with CoreBond will fill and bond together all possible cracks and voids, if done right. The very long open time makes a huge difference.

Ok, now I'm tracking. Here's why I wasn't.

The boat's situation is non-standard. The top-skin is gone. It no longer exists, can't change history (and don't worry, the yard is gone too), and all the non-skid areas are gone. New top-skin laminate will need to be glassed. Also, recreating the prior deck profile that included a teak deck is desired, because that profile with the teak included a scupper channel out at the gunnel. Teak is not going to be re-installed, however. So, an overall deck schedule to accommodate this profile is being sorted out, which might have core high on the scupper side, but of course it will all get glassed over and tied into the scupper gunnel area.

Since a new top-skin will be glassed in, and since it's recommended to work in all Iso Poly, I was wondering if non-skid could be done in Gelcoat as the final finish (seems like this could eliminate paint steps), and if so how is this done with the griptex? Or have I missed something, and this is a bad idea?

Thanks for the CoreBond background. The concern would be if any cracking existed beyond the area to be treated. Guess will need to do a few more inspections.

By very long open time making a huge difference, do you mean the time available to work with CoreBond before it cures?

Thanks for your guidance, it helps a lot!

[phorvati]

Scott, so are you going to be painting a 2-part epoxy paint over it?
Minaret I had another peel-ply question. Should i use it in-between layers? Also after the last layer of 1.5oz CSM, should i use the peel ply? I ask because I plan to do non-skid with cabosil-thickened gelcoat and roll it with a deep nap roller. This is what did 12 years ago and i liked how it came out. After the last CSM layer and fairing is done, I will probably do some sanding to level out the edges and I am beginning to wonder if i need any peel ply at all since I dont need peel ply smooth finish to roll the nonskid gelcaot.

[Scott Fuller]

Originally Posted by phorvati

Scott, so are you going to be painting a 2-part epoxy paint over it?

I am using KiwiGrip for my non-skid. I took it to Sherwin Williams when I did my cabin top and had them match it to my existing non-skid color.

[Reefmagnet]

About three years ago I redid my normally submerged pool step's non skid using washed and sieved course beach sand and epoxy, applied before painting with two pack epoxy paint. Cheap compared to kiwigrip because the sand makes up the bulk of the mix. I have to say it's non skid properties are excellent - if not actually a bit harsh, the final finish looks surprisingly good and although I had some concern that the paint would wear away quickly, so far it hasn't done so. I reckon it would work well on a boat too, although a slightly finer sand would probably be better.

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[mitiempo]

Or ground walnut shells - available at most marine stores.

[lateral]

Peelply = no anti-amine washing & no sanding.(except joins and the odd edge-very lightly)
Important in keeping the integrity of your structural glass, especially woven.
Also soaks up a little resin for a better glass/resin ratio.
Vacuuming you gotta use it.
Why would you not use it?

[phorvati]

Originally Posted by lateral

Peelply = no anti-amine washing & no sanding.(except joins and the odd edge-very lightly)
Important in keeping the integrity of your structural glass, especially woven.
Also soaks up a little resin for a better glass/resin ratio.
Vacuuming you gotta use it.
Why would you not use it?

Isnt anti-amine only for epoxy? I am using polyester. Ok i get the resin ratio. So my layup is
1.5oz CSM/laminating poly resin
Corebond/coosa
24oz 1708/laminating poly resin
24oz 1708/laminating poly resin
1.5oz CSM/laminating poly resin
1.5oz CSM/laminating poly resin
fairing/sanding
Cabosil thickened gelcoat(waxed)

and you are saying peelply after each fiberglass layer(CSM or 1708). And I might not need fairing/sanding step. It would be just light sanding.

[minaret]

Originally Posted by phorvati

Isnt anti-amine only for epoxy? I am using polyester. Ok i get the resin ratio. So my layup is
1.5oz CSM/laminating poly resin


Step 1.



Corebond/coosa



Step 2. Then sand/ chisel any Corebond squeezeout to prep for top layer of glass. Usually I do the edge grinding first so all grinding is done before laying Coosa, to mitigate the risk of hitting core with the grinder.



24oz 1708/laminating poly resin
24oz 1708/laminating poly resin
1.5oz CSM/laminating poly resin
1.5oz CSM/laminating poly resin




Step 3. You should be able to do this whole layup in one go, as long as it's not hot out. Make sure you're using poly iso resin that is not accelerated. Peel ply after the final layer of matt is a good idea, for the aforementioned reasons. One ply of glass at a time would be silly. Get everything laid out in advance, catalyze 2 qt batches, wet out with rollers, etc etc. No problem. Roll out the final plies of matt with the fattest longest roller you can find. It'll ease fairing some.



fairing/sanding



Fair in Rage. Not Rage Gold, or Rage Extreme.



Cabosil thickened gelcoat(waxed)





I assume you suggest thickened gel for a nonskid finish. I'd suggest you apply several rolled on coats of gel as a primer first, after fairing, to seal all pinholes and do final fairing. Fair in Rage to 80 grit, then roll on 3-4 coats of gel real heavy with wax in the last coat only, 30 min between coats or until tacked off. Then sand fair to 180.





and you are saying peelply after each fiberglass layer(CSM or 1708). And I might not need fairing/sanding step. It would be just light sanding.

A few pointers added to your text. There is absolutely no dodging the fairing stage.

[phorvati]

Originally Posted by minaret

Step 3. You should be able to do this whole layup in one go, as long as it's not hot out. Make sure you're using poly iso resin that is not accelerated. Peel ply after the final layer of matt is a good idea, for the aforementioned reasons. One ply of glass at a time would be silly. Get everything laid out in advance, catalyze 2 qt batches, wet out with rollers, etc etc. No problem. Roll out the final plies of matt with the fattest longest roller you can find. It'll ease fairing some.

wow, i have 12 feet by 14" area. It will be in the 50s, and i can add heat lamps underneath to get the temp higher if i want to. So yes I have the means to not let it kick too soon due to heat. The question is do i wet one at the time as i unroll them onto my large rectangle area making sure air is gone with each one, or do I dry-fit all 4 layers in-place and then pour resin over the top and wet out with laminating roller.

[minaret]

Roll up all plies, then lay them down in order starting at the bow and rolling aft. Unroll a few feet of the first ply, wet out, then a few of the next ply, wet out, etc etc. So, if you have 4 plies, as you go down the deck you should be pushing all four rolls of glass in front of you. This way you are doing all four plies all at once, no back and forth. Make sure you have a helper. Wet out and roll out 4-6' sections at a time. The other advantage of this method is that if the resin starts to kick on you it shouldn't matter, just dump that pot, make a new one, and keep rolling. But you gotta hustle!

[phorvati]

Im very pleased how the coosa and corebond came out. Deck is already very strong and i am yet to start the top skin.

[sneuman]

You need to keep things in perspective. Why did the balsa rot? Because the deck hardware was not properly bedded. How long did it last even without properly bedded hardware? How long do you expect to keep the boat? So, what if you get a fancy (and very expensive) coring material and water gets in ... you will still have water in the sandwich, it just won't rot said fancy (and very expensive) coring material. Don't waste $$. Use balsa again, but do it right this time. Btw, I re-cored my entire deck and so have some experience with this!