Hello
I just finished foiling a set of fcs quad fins (see pics below).
They’re made from 3ply pine, and I’ve inserted some nails that run from the fcs tab through into the body of the fin (the pic below is before I trimmed the nails). Hopefully it’l be strong enough. Any advice on the foiling/tab-strength etc would be sweet, but what I really wanted advice on was the glassing. I’ve got some poly resin left over from the last board shape I did, but no fibrecloth. Do I NEED the fibrecloth? or can I just glass over the wood.
Thanks in advance.
Check out this video
https://www.youtube.com/watch?v=QvRBWiUjlR0
Using fibreglass cloth with give the fins strength and I don’t know whether the resin will form a strong enough bond with the wood if you dont use the cloth i.e the resin might chip off. In all the videos I have seen of this type of thing all have used cloth so it’s probably the way to go but I’m not talking from experience so don’t take my word for it.
Hello Elbretto,
The fins look very nice, and the nails are an interesting idea.
If they were my fins I would fill in around the nails with resin plus some filler ( glass spheres or fumed silica) and then use fiberglass cloth, so that there are two layers per side on the tabs going part way up the fin and one layer per side on the rest of the fin. I broke a similar 3 ply fin at the tabs (without the nails) that was only one layer of glass per side. The plys are weak when they are carved away for the tabs.
Hopefully the more experiened folk will add to this. You could also make it an experiment by trying just the resin (I would be afraid of the nail breaking the fin plug) or a different type of cloth for reinforcement.
-J
If “fibrecloth” means fiberglass, then the answer is an emphatic YES. Otherwise, you really aren’t “glassing” anything by just using resin. The term “glassing” means applying a lamination of fiberglass cloth and resin to a surface. Simply coating the fins with resin will add no strength. It will keep them waterproof until such time that they flex and the resin cracks. Then, you’ll have soggy fins with no added strength. You’ll also want to seal around those nails really well. Unless you’re a fan of rust.
4 layers of 4 oz per side is pretty safe (or 2 layers of 6 and one of 4). Make sure there is a SOLID, CONTINUOUS set of layers from the tab to the body of the fin, otherwise those tabs will snap right off (I know this from experience). I wouldn’t bother with the nails…the resin won’t stick to it and it’ll be a great conduit to bring water into the wood core…and when your fin breaks (as it surely will the first time you take them surfing, if you don’t glass them), it’ll leave nasty stabby bits exposed. You’ll also want to fill the area where the fin screws contact with very dense milled glass fiber, otherwise you’ll push right into the wood tab, even with a couple layers of glass on it and compromise the whole fin.
Glass roving is also your friend. If you have a local glasser, if you ask nice, they’ll often give you their scrap fiberglass, you really don’t need much for a set of wood keels.
FYI, glass-on wood fins are much easier than anything going into a finbox…you need a lot less precision to get them to work right!
The nails probably made the fins weaker splitting the plys. Use 5 ply and you could get away with varnish, but they would need costant maintenance.
Sure will. Better off just doing glass-ons. Cut the tabs off, glass them on.
I have made wood fins in the past. I’d baste the ply with several coats of lam resin, then glass as usual. The tabs will increase the frustration of the glassing process trying to get everything glassed for strength.
I used to do the Nail trick in early generation FCS molded fins because I kept snapping tabs off during turns.
When I started making wooden fins I also tried the nail trick, and all that did was keep the bent fin attached to the board when the tabs snapped. I’ve also used stainless screws into the base of Fins unlimited single fin box fins. Stainless is only Stainless in the prescence of oxygen. Encase it in resin, it will rust. The fins which I installed these SS screws into, had sucked water and allowed the wood to rot. I’ve since replaced them with carbon fiber rods epoxied in, but honestly I believe the many many layers of cloth on the tapered base of the fin make any additional reenforcement unnecessary.
Now I strengthen wood fcs tabs with fiberglass or Carbon Fiber roving into grooves I made on both sides of the fin’s tabs, and make sure several layers of cloth extend from wood fin into tab itself.
I have some small plywood fins that the tips snapped off when glassed with 3 layers of 4 oz on each side, though a lot of that was sanded off in secondary foiling stage.
Not using fiberglass cloth, and depending on the Nails to impart tab strength, is going to leave you with nails sticking out of your FCS plugs. Perhaps you can find the fin on the beach afterward. I never found some of my earliest attempts which were woefully inadequate.