dearjohn said..
that's a really interesting fun setup. How does it perform?
It is my favorite. It is faster and looser than a traditional setup. These are size M fins, small for my weight (97kg), but this board has thin rails that do not need big fins to provide hold, so I can reduce them to get more speed... and the rails work even better at speed, a virtuous circle. The setup above is for my "max glide & speed" board. I also use the glass version, not carbon, as I feel a bit of flex helps reduce drag in better keeping the fin in the water flow.
Side fins provide hold, the raked part of the traditional template keeps holding through all kind of trajectories
The center fin has less drag than a traditional template, and also frees the tail, you do not have the added latency of the raked part, especially at low speed (top turns), but keeps hold at speed where it is needed as it still has depth. A bit like spitfire wings that were used in WWII planes that provided a manageable stalling.
I use bigger fins (L) for my "vertical surfing" SUPs, more drag but more hold to be able to push harder on the fins to tighten turns:
I use carbon sides to push on them and have a direct feel, with glass rear for looseness and speed.
On my fish for slow & weak waves, I use rear fins with less depth to avoid fins gaining too much hold at speed, that I find can lead to tracking in quads. Small sides for more speed for horizontal surfing.
A rule of thumb is to picture the area covered by a fin in a second as a measure of the fin lift. A tall fin covered area will increase more with speed than for a low aspect ratio fin.
And on my SUP for small hollower waves for vertical surfing, a compromise:
Note that FCS is now also using an elliptical outline in the center fin of their most advanced design, the H4.
At 2:01
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