i want to make a old school classic noserider with a glassed in fin but the first time i glassed in a large fin it broke off and havent done one since. i used the technique in glassing 101 is there a different technique for larger fins?
Thats that way I do it, is a good method. I would say you didn’t use enougth glass of roving (glass rope) If you cant get rope ot roving then cut a piece of 6oz coth and put out the long strands. I use 5-7 piece of rope on long board fins and 3-5 for short board, (each piece of rope has 5 strands)
On large fins I like to sand a little fillet in the fin base to give extra area for bonding and also means I can use a touch more rope.
First off you need a min of 2 oval patches of glass under were the fin is going to go, make one slightly larger than the other and put that on the bottom. I find its better to put the patches under the glass, but if you forget they can go on top but tha makes extra sanding. sand the area with 60 grit for a good bond.
See the patches under the fin, I’ve just alligned and tacked the fin in place with some 5 min epoxy, some use glue gun glue or resin but this is what works for me. The spring clams are great for holding it in place while the glue dries but you can also use putty or tape.
Then you need cut out 2 layer of cloth for each side and get some fin rope. make the rope about 2" longer then the base of the fin.
Now put on some glove coz here comes the messy bit, it helps to have a spare pair ready aswell. mix up some resin and soak the rope, hold on to one end, it elps to tape up one end or tie a knot in it. then when its saturated squeeze out the excess resin through your hands.
Run a piece of wet rope either side of the fin so it extends about 1" ether end of the base and smooth it out with a finger.
Change gloves. seperate the patches for each sied and wet them out. Brush the resin up fin and around the the base. Then att the patches so they start on the board then cother the rope and go up the fin. Work out any air bubbles with your fingers or a small squeege (credit card size, I raide shpes for the plastic gift/top up cards) Pintch the glass together along the edges like your making a mohawk.
Come back latter once the resin has gelled and trim the edge with a blade. onse the resin has fully set you can feather the edges of the patch and use a file or some sand paper wrapped round a pencil to et a nice smooth transition at the bass of the fin.
Then flip the board over and hot coat the fin avoid getting resin on the bottom of the board for now, just paint the side of the fin, gravety will stop resin pooling at the bass and a few drips on the tip are a lot easier to sand.
Rember to sand the resin and resin at the base before hot coating the rest of the bottom.
Never had one break so far, the one above actually had a meeting with some submerged rock and only had a few chip on the leading edge.
Hope that helps.
Do like Woody says, good advice and well done instructions. Keep in mind that if you hit rocks or the bottom and your fin comes off, it’s not necessarily a bad thing. A bad thing is when the fin is over-glassed on and when it gets knocked off, it takes with it most your bottom and/or rails. Just glass it enough to hold in the water conditions, not the bottom conditions.