glass on fin question (pics)

Ok so the ‘blue jimmy’ is coming along nicely and I glassed on the fins yesterday. I read through the archives and interpreted the information as best I could.

Now I’m wondering if I did it right. I used hot glue to tack the fins in place at the desired cant and toe-in. I cut fin rope and added three strands to each side of each fin, then cut a 6oz patch that covered most of the fin on each side and two 6oz footballs for each side of each fin as well.

Needless to say I made a mess with all the resin so now I’m sanding it all flush.

My question is this - when I sand this down won’t I be sanding the glass patches that are holding the fin on? If I try to sand it all down flush it would seem this would be the case. Same thing for sanding the fin.

I glassed them on after hotcoat (because I got confused and misread a post) - will this be a problem? I assume that once I’m done sanding the fins I have to hotcoat them again to fill in the weave?

Here’s a couple pics. Thanks for your help - Santiago

WHen i do my fins I just sand it so there is a smooth trasition to the fin it is going to be slightly raised over the deck but only a little

As far as glassing after hot coat it is not that big a deal you just have to sand very well before setting the fins otherwise the resin won’t bond well because of the wax. It is not as strong as if you do it after laminating but if you surf spots where your fins always break on the reef it is better because it will make a clean break instead of tearing apart the bottom of your board. I don’t know if you are going to gloss coat or not but even only gloss coating the wood fins would look great.

Thanks Skeletor. I sanded the hotcoat really well so that shouldn’t be a problem (hopefully). I’ll just sand it well again before the gloss. And thanks for the fin gloss idea, hadn’t thought of that.

Jimmychuck, didn’t see a mention of “roving” or fin rope used here. Also don’t see it in the pics. Did you use any? If so, how many strands? Also hot glue is a bad idea, even though many use it now. After 15 years in ding repair, I’ve noticed that when fins are tacked on with hot glue, they are never completely rigid. In fact, they wiggle slightly with every bottom turn and cutback. What happens is it starts to pull up the lam from the foam, and eventually the fin breaks off, but not without a big delam left behind. This also occurs if the fin takes a good hit. If you use lam resin for tacking your fins on, it’s much stronger, plus in the event of a collision, the fin will usually break off clean without a delam, making for a much easier repair. As far as sanding, it only comes out clean and strong if everything is applied cleanly. The roving should be shaped with your gloved fingers to form a perfect transition or “ramp” going from the flat up onto the fin base, and use your fingers to point the roving off the ends of the fin both front and back. Then your 2 layers of glass should be applied flat and cleanly so that when you sand it, the shape is already there and you don’t break through your patches, which would negate the whole purpose of putting the glass on it in the first place.

Good luck!

Thanks LokBox. I did use roving, three strands on each side of the fins, and I did make the ‘ramp’ up the fin and the fillet front and back. First time glassing fins on so I suppose I have a fin repair to look forward to.

I’ll try and keep the sanding from going through the patches and just smooth the transition instead.

Thanks for the tips.


PS - Where can I buy your boxes down here in SD? Mitch’s didn’t have any…

No worries, next time use 6 strands or 8 for keels! Our boxes are available here - Thanks


Are you saying 6 strands of roving on each side of the fin or 6 strands for the entire fin (i.e. 3 on each side)?

Best of both worlds: use 5 minute epoxy from a hardware store to tack on the fins. Almost as instant as hot glue; sets up as hard & as compatibly with the materials (poly or epoxy) as using lam resin. 5 minute epoxy can even be tinted with regular resin tint, if you need to.

Howzit the fishexp, That would be 6 strands on each side of the fin. Aloha,Kokua

The worst feeling is to set up a fin, think it is perfect, come back in a few hours after the resin has gone off and, upon closer inspection (e.g., viewing it from different angles), realize that it is off by a slight tilt or not quite what you wanted. Really SUCKS! At that point you have two choices; live with it or grind it off and do it again.

The advantage of hot glue is that you can set the fin(s) in place, hold the board at different angles/perspectives to make sure that it is set right, and then if you are not happy with it, BINGO you just snap it off, scrape off the congealed glue, and try again (try that with a fin set in resin).

And having a hot glued fin break off somewhat easier (e.g., if it hits a rock) may be an advantage as that also means it will most likely break off CLEANER (instead of taking a huge chunk of fiberglass and underlying foam with it).