Swaylocks is the greatest. I just finished sanding my first epoxy/eps board this morning and took it out for a surf. On about my third wave, the bottom turn tore out my whole fin box, It seems like when I set the fin box It overheated the foam. So now I have a finboxed size hole in the bottom of my board. WHAT DO I DO NOW? How do I keep this from happening again with my repair.
when you fiberglassed the fin box in did you use fiberglass to reinforce or did you use cabo-sil, aero-sil or whatever you want to call it.
sometimes reinforcing with glass weakens the strenght of the fin box.
good luck with replacement.
Howzit jfocker, Did you use only lam resin for the box installation since you don't want to use sanding resin because you won't get a good bond. Also turbo has it right about using glass around the box, I use the same resin mix that I install FCS plugs with and it works just fine. At least you don't have to remove the box just the old resin which is easier.Aloha,Kokua
I was used cabosil and resin reaseach epoxy with no additive f. I was left with exposed crunchy foam where. I think I got a good bond between the box and the foam, but the heat musta melted my foam. Any ideas about how I fill the old hole to put the new box in?
You gotta reinforce that whole area around the box anyways, so rout out enough foam to install woodies at least 3/16" wide and slightly deeper than the box. Overlap the end of the box by at least 4".
Some guys put in a top plate for the box to rest against for extra strength, basically a full wooden box for your finbox to rest in.
Don’t use fins much longer than 10", or the leverage just rips out the box.
No hotbatches, use chopped glass mix for strength.
Posting thru to the deck is another good idea for extra strength.
Yes, the exotherm melted the foam around the box. This can be a tricky thing.
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Real imprortant. You must get the resin out of the bucket as soon as your finished mixing. We had these melt downs years ago and found that if you let it heat up in the bucket, for even a minute, you were asking for trouble.
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Keep the resin cool before you mix it for boxes. I like my resin and hardener to be under 75º before I start to mix. For laminates I actually like it a little hotter.
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If your using 1# foam, you must attach the box to the deck (through hull) I do this by drilling a hole through the rout hole to the deck and the putting a piece of tape over the exposed hole on the deck. Shoot the boxes and then puyll the tape after the resin has kicked. On long single boxes I put one of these holes in each end unless I have a stinger. A stringer is enougth support by itself.
Now that you have this issue, it’s actully pretty easy to fix. Go to HD or Lowes or Ace and get yourself some of that foam in a can called Great Stuff or Insta-foam or some other like product. Use that to fill the hole, let that harden up and then reinstall the box with resin taking the precautions above. If your not supported by a stringer you once again have to through hull anchor the box. The only thing wrong with kind of repair is that it doesn’t look to good. Time for some creative cover up.
Two other options for next build or for this repair. use ofish’l boxes that are capped and place box prior to fiberglassing the board or in your case for replacement… Put reinforment patches around box when glassing also. I also will use a 1:1 epoxy paste to set the box. The paste is a thick peanut butter consistency, it will not get smoking hot and you get minimal foam absorbtion. Sets in 15 minutes and cures in about 6 hours.
I get it in 1 pound tubs, but you can buy small syringes of this at hardware stores. You also can add tint to this product. I think it’s called powerpoxy. I will have to check my supply tomorrow for the actual name.
Thanks Greg, I would have never thought instafoam. How cold can have the epoxy, I am in california it has been pretty warm, can I put the resin in the fridge for a while till it feels cooler, or would that cause me curing problems? Also, which filler works best, Cabosil, microspheres, chop glass, or do I just use resin? The board is 10’ and I am a large guy, other than the drilling holes to the deck, is there anything else I should do to make it strong enough for the bigger fin?
A good place to get 5 minute epoxy is from a hobby shop. I use the stuff for all kinds of things. It does have it’s limitations… not real strong and not real water proof and it yellows. But it is fast and sticky and doesn’t exotherm too bad. CMP is right about O’Fish"Ls. That’s what we generally use. They fit pretty snug into the rout and don’t seem to build heat. Futures and Lokbox are good as well. We have more problems with FCS. The O’Fish"L long boxes are nice as well and we also use their leash plugs. We don’t have any problems with the long boxes as long as the rout is tight. Epoxy is strong enough that excess resin around the fin box for strength isn’t nessasary. So if your using one of the box systems try getting the rout snug and you won’t have as many problems in the future.
Oh yeah, If you do use an epoxy paste, it will have a waterproof rating. Get one you can tint and that is waterproof. The powerpoxy stuff I use has a couple different types, so get the waterproof one.