alright,Im going all the way and and building fins for my boards too. i’ve searched the archives but didnt really find anything on foiling these fins. There was a lot of theory but without ever foiling a fin it was a little over my head. So what are some of the basics of foiling these fins or any fin? By looking at some standard fins, I foiled what I thought might work. You can see the thickness by the wood grain. here is my first custom fin…
You might want to start with thinner wood. I use 1/4" ply. I foil the ply, then attach it to a built-up glass & resin base. I’ve been experimenting with dovetailing the fin to the base and then adding rope to the front and 3 layers of volan to each side. Here’s one I foiled and then painted red before glassing. It was for Surfore because he wants all his fins red.
Draw a line on the planshape about 25% of the way from the front edge to the rear edge. This is your wide point. Although you may want to change it a little, 25% works pretty well for everything, and you never really want to be outside 15%-40%.
Use a different layer in the middle of the layup as a marker.
Draw a smooth taper from the rear edge to just behind the wide point. Take your time! Make the layers of the ply/glass into perfectly shaped contour plots.
Make the front edge rounded. You may want to finish the front edge by hand, a sander works well on nearly flat surfaces, but it takes a much steadier hand to do a tight curve. And, the front edge can be done pretty fast by hand.
You’re brave showing your first fin. After a dozen more you’ll want to burn it so no one can see it again. Keep at it, it will come with time. Glass is a lot easier to get feedback on, the layers show you the contours and let you get pretty decent pretty quickly (like, if you are instructed well and have good equipment, maybe something you’d want to show someone after 4-5 fins).
Hey Zach T,
Blakestah’s advice is sound IMHO.
Work toward achieving no flat spots in your foil. Start with very course grit (24) on your grinder and just get the general ruff foil. Then change to 80 grit and try and get real close to the final product.
When you think you’re close take an 8" half round bastard file and fair the leading a trailing edges. Then take block of wood 3 1/2"x 8"x 3/4" with 60 grit and fair the whole fin. Have a close look at things and go back to you 80 on the grinder to fair the uneven spots out. Then block sand with 80, 150 and 240. You’ll end up with something that will serve you well.
Dusty Trails, Rich
“You’re brave showing your first fin. After a dozen more you’ll want to burn it so no one can see it again.”
so its that bad.i have two different foils for that fin. should i make it one or keep the two seperated? if they are kept separete what about the area between them. should it be kept thick and taper it off at the very end? Thanks
hi zach…
did you see my private message [‘p.m.’] to you yet ?
THAT may hopefully answer the last question .
Cheers mate !
ben