JS wrote:A pair of fins, canted equally in opposite directions, generate the same net vertical lift as two uncanted fins. The canted ones have slightly more surface and drag relative to useful lateral lift though, so may be slightly slower.
However, canting can affect handling. With fins canted outward, the leeward rail will get 'sucked' downward somewhat while the windward rail will get a bit of vertical lift, compared to uncanted fins, all other things being equal. In other words, outward canting causes more heeling moment, which must be overcome by the rider. Inward canting does the opposite.
Yes I was dead wrong
I was (incorrectly) thinking 90 degree cant = airplane wings = vertical lift and so I incorrectly assumed (heavily influenced by rista video) that any angle less than 90 would simply have a component of vertical lift
Not the case. The PRESSURE is what matters and due to the drift angle, all three fins will have positive pressure on the leeward side. making the "lift" of the 2 canted fins oppose one another....
Now I'm really confused though.
This provides a balancing moment to the riders weight by lifting the heel side, and sucking down the toe side which would tend to flatten out the board. The lateral "upwind" lift still produces a moment in this same direction (albeit with a slightly smaller lever arm located at the CP of fin rather than the 1 board width away.) but still I can't imagine 2-4 degrees of cant really has a significant effect.
For "stability" somehow I intuitively expect that as the board rolled from flat, the cant would create a self righting moment keeping the board flat, but looking at a free body diagram this doesn't appear to be the case either. Boardlift (buoyancy and planing forces) are the only self righting mechanism as it rolls due to parts of the board losing contact with the water.
(ONE of the reasons a big fat board is beneficial)
Guys who ride this stuff, what do you "FEEL" with canted vs uncanted fins. !!??
any other ideas?
Am I missing something?