Hey Rohan, they're some sweet fins !!!
Do you make them all , or build some and get some made elsewhere ?
and what sort of wood and resins are being used ?
What a Great gallery of classic designs.
They're all my own tawdry handiwork Brett.
The wood is mostly Paulownia. The Spitfire is Bamboo ply and Balsa. The full flex Brewer has a fibreglass reinforced Paulownia spine with cork on the sides and no outer fibreglass to allow it to flex properly whilst still being thick. The edge flex Brewer has a cork trailing edge to allow flex, again without outer fibreglass in the area required to flex. The resin varies depending on what I have on hand at the time - some are polyester and some are epoxy. The two flex ones I made sure I used epoxy because of its better flex characteristics.
I made the flex Brewers (I still haven't finished the edge flex design) because I wanted to know if a thick flex fin would perform any better than the standard thin flex design - of which I'm not a great fan. I can report that I'm still not a fan of flex. The thick one had the general performance enhancements you get with thick foils, but the flex/rebound and associated timing of this adds another factor that I don't like to have to take account of when I'm surfing. Too unpredictable for my liking. Maybe fun in waist high waves, but no good for me in anything bigger.
For those of you interested in investigating thicker foils this is a good place to start.
This is set to search for symmetrical foils with a minimum percentage thickness of 13%. Surfboard fins operate at low Reynolds numbers (typically around maybe 600,00 maximum), and generally thicker airfoils perform better than the thinner at large angles of attack at low Reynolds numbers. As Bert Burger has suggested early on in this thread, the angles of attack generated when surfing are actually much higher than you might expect. Also generally speaking, foils having a location of maximum thickness closer to the trailing edge have worse stall characteristics, but at low angles of attack they have higher lift-drag ratios. It's all a bit of balancing act to get exactly what you want.
Great thread! Shame many links do not work any longer and the photos have disappeared.
Should have let this one die about twenty pages ago. About as scientific as Calif. Air Resources Board statistics. Typically Sways though.
A good read, thanks everyone!