Cant is the sideways angle of the fin to the board measured from perpendicular. On a single fin that’s 0 degrees and it has balanced equal performance in turns on both sides. However at 0 degrees the fins performance has a range of alignment with rider, board, wave that is optimal but then tapers off.
Add increasing angles on the fins and it shifts that optimal alignment of rider, board and wave so that the board needs greater angle to reach that optimal alignment.
Now is there a way to incorporate a wider range of optimal drive by curving the Cant, essentially providing a range of Cant in one fin ?
Keeping any basic Cant angle from base to tip, say 6 degrees, it’s possible to use a curve, either continuous or divided into two panels and fared together.
That curve would provide a range of Cant from a standard of 6 degrees up to maybe 12 degrees, possibly customised to certain alignment for a rider or board or wave or backhand Vs forehand with a different Cant configuration on both side fins or a Butterfly style single fin with a more subtle range of angles reminiscent of a Wishbone shape.
When you roll a board over in a rail turn, the cant of the fin might become less than optimal but you are now not turning off the fin, you are turning off the rail.
That is a very provocative idea. It is what I love about your posts. They always make me think and envision the concept presented. Drawing #3 catches my eye the most. Another way to channel water at critical angles. Mr. Chrisp, most of the time in a full rail turn, there is still fin involvement particularly on multi-finned boards. Rail turns still need fins otherwise we would be “sliding ass” like the old Hawaiian boards. It sure takes a lot of effort to work out a concept with so many variables involved in surfing. Keep up the “Imagineering” Brett. Onya.
I see that the hull is always engaged, then as the board tilts, the fin starts to interact and then the rail. But every element plays a part.
F`rinstance, Twins are similar cant and out on the rail but they have lots of Vee in the hull to initiate turns before the fins engaged.
heres a pic of a multi fin side fin and a Wishbone Single fin with the angles of cant indicated.
Its just a matter of varying the curve to create a fin thats optimised over a range of conditions much like a template curve.
Thanks for the comments Tblank, Ill be making a few of these to test the “Imagineering” design out.
when you watch finless surfing, they can really bury a rail and jam a turn - but in the last third of the turn the tail comes up, and the momentum spins them, so they’re riding sideways, sometimes spin all the way around. I can’t embed video anymore, but there is video of Derek Hynd at J Bay finless, you can really watch how the board reacts to turns. He puts a biting edge on his tail, and his channels, but like I say, it only works when the rail is sunk, once the rail is back up, there is no engagement. the board spins. https://youtu.be/6h4RzMWlugk
Its kinda interesting to me to watch finless surfing in the context of a fin discussion, because finless lets you see how much you can do off the rails alone, and how much and where fins really add to the board’s performance.
Hi Greg, I’ve already got orders which is good as I’m unemployed at the moment ! But Huck gets a free one.
The testing is going well and I’ll post pics and feedback here.
Keep us informed as you go Brett. This sort of thing really piques my interest. Your usual level of creativeness and craftsmanship is clearly evident too.
Making the tabs strong enough and foiling the inside will test your ingenuity - but I know you’ll be up to the challenge…
Rohan, inside foil is an interesting beast, take a fin with a flat inside surface and by introducing an inside foil it creates an area of concave from leading to trailing edge,(see pic below) But also a concave from base to tip. so you already have a variable cant included in any fin with inside foil, but its very subtle.
Im not revealing anything new here but fin characteristics generally follow a rule of thumb around the waves shape and power.
Fins for waves that are flatter/fatter/less power generally have more cant, more toe in, more foil, inside foil, are thicker, even the foil is further forward.
But as the power increases these characteristics are changed to create a more stable board so the attributes that promote stability are increased so less cant, less toe in, the foil moves back, less foil etc…
This experiment will see if a range of cant will cover a range of wave shape and power.
Rohan, I’m going with unfoiled on both sides to see how the Twin curved fin concept works on its own. Just rounded edges.
There will be other versions with inside and/or outside foil but I’m keeping this one Unbiased to begin with.
A lot of the basic Cant theory is that Cant is designed to work at a particular positioning, alignment, orientation of board, wave and rider, it’s not an ON / OFF alignment but more of a buildup of alignments that meet at a range of angles to create a sweet spot that provides grip drive and balance that gets you across the wave at a premium performance.
It’s a Bell Curve where optimal performance comes from many elements.
Curved Cant is an experiment to stretch that Bell Curve of Performance so that the sweet spot of grip, drive and balance is easier to get and larger so you can drive high off the wave, mid turn or find power on the flat.
A board should be able to have a wider range of control over many angles of orientation.
I like the name Quad Thruster, it explains how it feels underfoot… The rides a lot like a quad but with less need for rail engagement. I’ve paired them with neutral fins at the moment.
More to come.
Huck, I had a look for similar fins, there’s the Velzy V fin and the more modern Butterfly fin but the angle between fins on those is about 65 degrees and they create a lot of vertical lift. Having the fins closer in Cant like mine they both are independent but work together.
I’ll ride some more and give feedback. If they pass the testing phase I’ll beg RDM to whip up a printing file and use that to make a few.
