what are the performance characteristics/benefits of the orca fin, compared to the standard dolphin like fins? (i tried searching the archive but couldn’t find what i was looking for)
what are the performance characteristics/benefits of the orca fin? (i tried searching the archive but couldn’t find what i was looking for)
does it work in a thruster setup?
what kind of sander do you use?
thanks again!
This was more of a how-to demo, but the Orca is a basic raked ellipse with a mild cutaway. It works quite well, can be scaled up to whatever depth/rake/chord lengths (or aspect ratio) you like. It was designed to provide the best lift-drag characteristics of a stiff fin - I evolved to that design with my rotating fin system, it beat out fins with longer rakier tips easily.
The Orca does work in a thruster - it is about the same surface area as a G5 - it will certainly be quite usable, if you make one you can judge if it is better or not.
The sander I use is actually a very cheap angle grinder with a soft pad substituted for the grinding wheel. I think it was $30 or so at Home Depot. You could certainly use a bigger sander, but I think smaller is better for fins.
I forgot to mention - nearly all passes with the sander are made parallel to the max thickness line. Kind of a critical point.
thanks blakestah, my summer project if to lay up some fin panels, learn how to foil and make my own custom bases. so if i ever get around to it i will make some orcas!
There’s more to it than the steps I showed, mainly
the layup
the post-foiling casting of the fin tab for cant
the gloss finish
There’s plenty in the archives on 1), plusoneshaper did a little thing on 2) about a month ago, and glossing a fin is just like glossing a board…rough sand first, paint gloss on, sand to fine grit, and polish. The fins will work fine without the gloss, but no one will take your fins seriously without a really good sheen. Also, don’t gloss a flex fin…at least with polyester resin gloss.
I just finished glassing a set of a template that you posted last summer. What can I say, I’m slow. Came out pretty well for my first shot at foiling and glassing. I also made a traditional set that I rode today for the first time. I was pretty impressed. Not that they worked extrememly well, just that they felt as good if not better than the original. That and the fact that the fin tabs didn’t break off, I consider it a success. Both sets were wood core with 2 layers of 6 oz. on each side glassed with UV poly resin. Keeping it simple for the first few sets. Laying up panels seems like too much of a pain at this point.
I found that a half round bastard file really helps to get the leading edge shape just right. It’s kinda of hard to do with the sander.
This set is pretty thin overall, I’d guess around 6-7% of chord.
Fin on the right has been glosscoated. One on the left is hotcoated and needs to be sanded and glossed.
good show man…i’ve been thinking about making fins for about a year now and foiling has been holding me back. I had a eureka moment recently on making pufoam/balsa/CF core fins with CF shell using a molding method…light stiff and buoyant…actually made some progress the last few days…if i dont like the results i’ll go your foilin route…
