fin plugs and eps

hey guys I know everyone will say go pro-box but  I am a bit too far into the current board I am doing and I can't get hold of them here in NZ.

anyway I have hotcoated the board and I am ready to drill my FCS plugs in but I am having second thoughts on the strength of the foam.

the foam is around about #1.5 eps at best ( was given the billet of foam )

I was wondering if there are any good ways to strenghen the install of the plugs i have at this stage in the game? 

next time i will be adding high density foam inserts were the plugs or boxs go.

cheers for any ideas

 I had a search but could not find much on it when this far into a board



All you can do at this point is a proper install, and reinforce the skin around the plug… extra patches. It’s really important make sure the H-pattern hole is drilled properly, going all the way through to the deck, and leaving a pillar of foam under the plug. If the resin in the hole bonds well to the foam and plug, the only thing that can fail is the foam tearing out. To prevent that, reinforce the skin.

yah tis a problem along with the epoxy kicking off and cooking the foam. I had to cut out a saucer sized section due to rotorua type smoking and heat.  apologies TS. the only thing I recommend is to dip the glass in resin then put aside then mix the resin with some microfibres/glue powder till you have a paste and put some paste in first. place glass on top add some more paste then push plugs in. wipe excess. oh and keep the insides of the plug hole rough. poke a few small holes through close to the deck.


also wait until someone with a better idea gives you better advice 

use fcs fusion boxes


I know there is someone in nz that has probox just not who

for sure, go with FCS fusion. they already have the high density foam around them, and you don't have to drill through the deck. use slow hardner in that light foam. 

I'd say go with Fusion, you can still do it post glassing, just sand the board as usual then do the install. Likewise, you can still add a hi-dense foam insert then put the plugs in that. Just rout the hole right through the glass, add foam insert, then glass over and install plugs, just drilling into the hi-dense foam, not through to the deck.

However, if you're set on using the plugs as is, do what NJsurfer said, but I would do it in two separate pours, allowing the resin to cool down after the first pour so you don't have a major meltdown.

go with the fusion boxes, if you route the holes properly there is not much space for the resin to build up and get hot so you shouldnt have to worry about a foam melt down

cheers for the imput I am looking into pro box for the next one as i have a contact here in nz now.I think the skin will be strong as aounrd the fins as i have a heavy carbon tail patch (18 icnhs long by the width of the board) and 1x4 &1x6 oz cloth back there.... maybe glass on's could be an idea on this one what you thoughts. see pic.

cheers antony

so i got a cheap set of "shapers S-plugs" to try out hopefully these will bond to the deck skin better and help with stenght. I will drill the holes pretty tight to help keep the epoxy from heating up.



Put some plastic bags of cold water under the board when the resin is setting as cold sink. I use a solar shower bag…

sounds like a good idea bro may even add a few ice packs for good luck


remember that the obsticle that every fin system must overcome is that the foam adds little or no strength.  That means that the only strength will be found in the skins and the box must bond to the skin gain strength.  Any glass or chopped fiber merely pressing against foam is wasted. I have had succes in eps  by using the two pour method noted previosly and adding micro ballons to further reduce heat.


Greg is correct about adding a layer of cloth over ANY embeds in the eps blank.  The reason is not only strength, but the fact that when eps expands, it tends to force leash plugs, fin boxes, etc out.  Not really pushed completely out, but enough to fracture the resin around it and create a leak path into the blank.  The easiest method to overcome this is to only use pre-lamination style embeds (capped or raised) and just glass over them when laminating.  Put the embeds in when you seal the board using the same micro-balloon slurry.    For getting around melting foam, there’s a several of methods I use:  (1) Use polyfoam inserts bonded in place with white Gorilla Glue. (2) Use epoxy putty or 5 min cartridges, and a shallow fill after it’s cured. (3) Use 2-part urethane pour foam, but you’ll have to clamp down the embed since the foaming action will push it out.  A couple of padded shaping weights works for me.   I glass over pre-sanded down FCS plugs by putting modeling clay in the slot and screw hole and cutting out the cloth when cured (use a drill on the hole).  

hey guys thanks for all the imput. I put the fin boxes into day. i used a combination of a few different ways and i think it should work.

I ended up using the "shapers-s plug" and the FCS system of attaching to the deck skin. I also after drilling out the plug hole took a drill bit and removed a groove of foam 1/4 by 1/8 under the skin on the edge of the hole. I was hoping that this will help bond the fin plug to the skin better.thought this would help by having epoxy bonding to the skin from the under side. The tail area has a carbon patch you can not tell the foam was groove out under the skin.

I followed the advice and poured in two pour and keeped the shaping room at lower temps and had not problems with exothorming

i will post a pic when it all dry

thanks again