Great stuff Rob! I am starting to appreciate the silent flight of my Slingshot

Nice soundtrack

DavidJohn said..
Do those foils come with a volume knob..

Yes, it is a piece of sandpaper :-)

Seriously, if you want to reduce the humming you must sand the trailing edges (mast and wings), ideally in a asymmetric way to lock the trailing vortex on one side of the thick trailing edge. See my post with schemas at www.seabreeze.com.au/forums/Stand-Up-Paddle/Review/Fin-Whistle
You should aim for the case #7 of Fig 6.35, but without getting an edge that can cut the skin.

Myself, I prefer the humming than taking the risk for me and others. Plus you get used to humming, the auditive feedback is welcome to know what is happening (On my foil, the humming seems proportional to the length of mast in the water). And it makes the prone surfers think twice before thinking dropping on you, it save you the trouble of whacking them on the head with the paddle :-)

Seriously, I nearly never shout on people dropping on me (never on small kids / girls / women anyways), as I consider that I can get so much waves that it doesn't matter, but I had to shout to a guy and threaten him with my paddle as he was trying to drop on me nearly on my trajectory as I was foiling... there are some suicidal types. I try to go foil on peaks where I am alone, but of course seeing me taking wave after wave attracts always some prone bozo who think he can thus take also waves... of course he catches nothing and leave disgusted, but this was the first time saw one trying to drop me, with of course not a chance to actually catch the wave.

Stev0 said..

colas said..

Seriously, if you want to reduce the humming you must sand the trailing edges (mast and wings), ideally in a asymmetric way to lock the trailing vortex on one side of the thick trailing edge. See my post with schemas at www.seabreeze.com.au/forums/Stand-Up-Paddle/Review/Fin-Whistle
You should aim for the case #7 of Fig 6.35, but without getting an edge that can cut the skin.

This was explained to me the other day when I was talking about my Neil Pryde windfoil humming loudly. I want to get a bit more information about how do sand the trailing edge correctly before attacking my wings. Any more advice on that?...

You could ask Alex Aguera (via his "Go Foil" account on facebook), as he has stated that he would tell people how to do it if they asked him.

On my fins, to get the case #7, I just sand by hand on one side of the trailing edge to round up one side, trying to shape a round edge rather than a sharp one.

Ah ah ah... I don't believe it.

This was the first of my foiling video I didn't upload to seabreeze, thinking "Why bother, the usual band of fools will just nitpick on irrelevant details, ". I am so sad to be right...
And to think some are accusing me of always speaking of these mast positions...

Let's focus more on the important parts: technique: I do not pump vertically (a la "Huntington hop") on takeoff because I do not have yet the balance needed to start the flight without being destabilized in the first meters (you can see an example of this at 1:25). Instead (but I do not do it in the takeoffs in the video) I just pump longitudinally, pushing back & forth my feet to give forward acceleration to the wing and raise the lifting speed. I find it easier to enter the flight fully prepared, plus it is stabler in hot situations (late take offs, take offs in the foam) Note that I can paddle feet in the straps, so my feet are actually quite forward, and thus the mast quite backwards compared to them.

On the rest of pumping, you can see that the waves were very, very slow (5s period), so I am in near-stall mode (The wing, hence the board, is pointing upwards). This is the main problem, I should have focused more on getting more speed rather than lift.

And I also do not use my arms and upper body enough. And my feet are too contracted (toes are flexed). BTW, this is what an expert foiler told me when he saw the video: actual issues with my technique, not some imaginary drivel.

Seriously the tail dragging is not very important, as Finn Spencer shows us here (he starts at the center of the board): the technique is 10 times more important. One could even think he actually uses the tail to push on the water for leverage.

www.facebook.com/Gofoils/videos/658305287705088/

Colas said:- This was the first of my foiling video I didn't upload to Seabreeze, thinking "Why bother, the usual band of fools will just nitpick on irrelevant details, ". I am so sad to be right...
Guess that makes me the fool

Colas said:- I should have focused more on getting more speed rather than lift.
You won't get any speed without lift. That's what a foil does giving you speed from your lift , without it you are dead in the water.

Colas said:- Seriously the tail dragging is not very important, as Finn Spencer shows us here (he starts at the center of the board): the technique is 10 times more important. One could even think he actually uses the tail to push on the water for leverage. (no way)
Seriously it's a kid on a flat water start on a micro board and you want to compare that technique to your video. The whole point about my rebuttal, is just maybe you are wrong but for some reason, you won't entertain the idea or consider other expierenced advice. I'll leave you with this.

Piros said..
This is GoFoils reply to my video on how to stop the hum:-

Usually it is the back wing but also can be the front wing. The back one inch should be sanded to almost a concave. Look for trailing edge going to a rounded shape towards the middle of edge either top or bottom surface. Think of it releasing the other way like a concave. Usually last 1/4" of rounding is the culprit so try and see if you can see it. Put sideways in light as it is very hard to see or put straight edge on it to help see it.

Interesting. It looks like the wing trailing edge is somewhat near the case #3 of the figure above, and he advises to "remove the bump" to get to case #5. Or going from #6 to #8. Makes sense.

Piros said..
This is how the rear front wing looks on a Kai Go Foil , it's quite square from the factory.

Ah, it looks more like case #1 then.

colas said..
To continue with videos that show how a foil works, this one is quite interesting as it mixes two types of pumping:
The vertical one, and the "roller coaster" classical surf action (or gulls in upwards winds on the face of a dune).
Or even three types, if you separate the simple vertical hungtinton hop from the more "circular" pumping where the legs push the foil forward at the descent.

www.facebook.com/patrice.guenole/videos/10214013237147332/

If it is flat try this way more fun :)

charlieuk said..
That doesn't really make sense to me, at speed if anything it would be worse and you will have to fight it even more. I cant see why you would want it different for the two conditions personally.

What I said is I have been at very high speeds already, and the foil is perfectly balanced at speed. Note that at these high speed, 1" difference on the placement of the front foot (space between straps insert positions) had very noticeable effects, the proper front foot position was quite obvious when tested at high speed. Back foot position is not really important.

So, your proposition being true(*): "if the foil lifts too much in the slow waves of the video, then it will be worse at speed",
simple logic thus dictates that the foil does not lift too much in the slow waves of the video.
If we have "B is false" and "A ==> B", then A is false.

Thus my analysis is that since the foil doesn't lift too much, the stalling is a pilot error, not a gear problem.

(*) actually, it could be false, maybe if the wing / stabilizer balance was changing with the speed. This is why I said that I'd rather have my foil tweaked for the high speeds (which is the case) because I cannot imagine struggling against the huge forces in play at high speed, whereas compensating for some inbalance at low speed seems doable. Hossegor waves can switch from mellow to hollow quickly with the tide.

colas said..

hilly said..
If it is flat try this way more fun :)

But much, much more dangerous. :-) A wheelchair is not my idea of fun ...
I never skated again after falling off a ramp on the concrete. As Gerry Lopez said, "The best surfer is the one that can still surf the day after."

Interestingly, on the video the rider is Patrice Guenole whose son was doing BMX competitively but had him stop and spend more time foiling because of the high probability of ultra-serious, crippling injuries in BMX.

Yes foiling is the rollerblading of surfing