Help! Bad burn-through on tail: best way to proceed?

Hi everyone – thanks in advance for your guidance. 

I’m almost done making my first-ever complete board – a 5’9’’ shortboard using RR epoxy, FCS II boxes. Some noob mistakes there but it’ll float and i’m really psyched. BUT…

i got a burn through (not just weave exposed – it’s all the way to foam) behind the back fin – it’s about quarter-sized, right over the stringer. 

i can’t just paint a thin layer over the burn through (right?) because it’s all the way to the foam so i’ll need strength, and anyway if i do that it’ll just be a bump. sanding the bump flat will take me right back to the foam!

So, instead, i’m planning on mixing up, say, 1-2 ounces of resin, taping off the tail just like for a hot coat, then applying that resin just to the last 12-18 inches of the tail to build up some resin there behind the back fin box with a new layer. then try and gently re-sand.

question #1: i ran out of those shaped stickers you get with FCS II fin boxes – **can i just use regular old adhesive tape like this? (** to cover up the boxes before applying resin? 

question #2: and then pull the tape when the resin just begins to get tacky?

question #3: the reason i plan to pull the tape – i’m worried that if i leave the tape until the resin is hard and just sand the tape away, i’m going to be grinding the fin boxes too far down when my problem is, of course, that i’ve taken that tail down too far – if i grind the fin boxes down even more, that’s just going to create ground-down fin boxes below the level of the coat, which i have to leave higher so i don’t burn through.

hope this makes sense. 

thank you for your advice!

Yes you need cloth, If you want to do it right. carefully sand around your burn through by another inch or so until you see the weave. tape off the rest of the board and re lam this new area. then apply small hot coat and sand carefully. don’t be afraid to hand sand around the tail area especially while you are getting the hang of things. good luck! post some pics

thanks, jcyr! i will try the glass patch + local hot coat. 

it’s so near back fin box i’ll have to tape that off – can i use regular tape and then pull when tacky?

Sand and tape around the area and patch with glass. feather the edges then tape around it and hot coat. Sand flush. Surf. I don’t see why you’d have to re hot coat the whole tail area, but pics would help. 

Also yeah you can use high temp tape to cover the fin box and pull t when tacky

thanks you guys! this is great. i’m actually delighted to avoid doing full tail hot coat. i’ve got spare glass and will cut a football patch, tape, glass that spot, tape, coat, sand. 



Cloth and resin followed by a coat of lam resin followed by hot coat.  This will leave you with a little more room for error on the sanding

I would use 2oz cloth for the small patch you describe

for removing tape/resin protecting a fin box slot, use a single edge razor to cut around the opening when resin is rubbery

okay, this morning i glassed/resined a football patch over the burn. tonight i’ll gloss coat then CAREFULLY sand tomorrow. will send pix and an update when i have something!

thanks everyone!