Greg, I’ve made clear ones but they don’t photograph well. But I’ll do some new ones.
I don’t think there’s a speed difference but there’s a control difference. The single foils are all lift all the time so they need to be the right size/ area for a certain wave size. The split foils can vary the lift as they speed up so they cover a wider range of waves and speeds.
Red boards, thanks for the props, I’m all over the place with lots of inventions on the go.
I just round the leading and trailing edges of the struts and leave it at that unless you think there’s a benefit to be had with more foiling ?
Distance make the foil/ wing grow longer.
Surf foils are different to plane wings because there’s a boundary between the water and air.
If you’ve got a wide surf foil, you need to keep it submerged or it pokes thru the surface and the air rushes in and the foil loses lift which is a disaster. It’s called ventilation
In fig A, a flat foil gives uniform lift across the span which is fine if you’re doing level flight like an aeroplane.
But in the surf you will want to turn, that means the very wide Outer tips will rise up near the surface but that’s not good if it ventilates. Maybe turn the tips down the avoid venting ? But lift is at right angle to the surface so a down turn tip doesn’t support turning…
However an upturned tip gives wide lift so you can confidently turn and weave down the wave knowing intelligent design is behind you.
If your design is wrong with ultra-wide down turned tips you need to drop the foil away from the surface to avoid venting but that downturned design doesn’t create lift when you lean during a turn.
The result of a wide foil is you need to nurse every turn, stay away from the tube and keep to the shoulder no matter how big the wave is.
I’m very impressed that my mentor Terry Hendricks moved from his patented wide foils to my delta shaped low aspect foils. Until the current commercial foil dudes change design, Surf Foiling is doomed to be a highly technical experiment that’s going to sit with ‘Tow In’ as a dangerous and difficult derivative.
Ive been foiling exclusively since 2006 and made over 300 foil designs or maybe 400, but take my knowledge and make a better foil that safer, easier to ride and will be a new journey for all surfers to try.
I know you’re reading this, just make the jump…
Brett, is there any video of Terry riding his papio foil? I’ve looked and cant find it.
All the best
Not that I can find, there’s a few still shots of Terry but that’s about it. Google Terry Hendricks / hydrofoil / Slicer Dicer.
I think there’s a lot of people here who wish they had more pics and video of their inventions, Surfboards and travels.
misplaced post
@surffoils,
Your assertions about wing shape and properties on a wave are fascinating, especially because they are in some ways the opposite of how conventional foil wing work when not in the critical breaking section of a wave. The wave shape and motion turn the dynamics of foiling in flat water or nonbreaking swell inside out.
One thing I thought you might find interesting, and may or may not be applicable to your designs, is one conventional foil maker has apparently succeeded in making wings for windsurf and kitesurf that don’t ventilate when the tips emerge, by using a grooved surface on top of the wing, claimed to act like anti-ventilation fences or shark skin. Sounds suspect, perhaps, but the video is pretty convincing that it works, at least in flat water:
https://vimeo.com/260463200
https://vimeo.com/258219952
Makes sense! Like leading edge tubercles with undulating wing surfaces reducing water flow toward the wing tip.
It would be interesting to make a fin that has the undulating surface, but not the leading edge tubercles, just to figure out how much the tubercles contribute vs the contributions of the surface undulations.
Or, of course, make a hydrofoil with tubercles and undulations and see if it works even better.
Given those videos are only 2 weeks old I’d guess the AVS will appear on GoFoils and the like soon enough.
Powered foiling is a bit different as the lift comes from the kite/boat/ electric motor whereas the surf foiling relies on the water flow.
With the non venting tips they can curve the foil upwards so it gives better lift when turning and that’s a big improvement.
