Hi Dspace, I had exactly the same problem with my new Sabfoil 799 that I bought a couple of months a go, it was doing my head in. I was previously a Naish foil rider and had never experienced this problem with their foils which are silent. I also went online and had a look at numerous videos like yourself, was it the stab, was it the front wing, was it both?? 45 deg, round off, sharp tips of not sharp tips..whatever I sanded it didn't make a blind bit of difference.until the other day!
I had a look at my Naish wings and tried to get my Sabfoil looking similar in profile on the trailing edge but the breakthrough happened when I actually sanded some of the sharpness out of the front wing trailing edge. I still had the 45 deg angle to it on the underside but I also took a little bit of sharpness out of the edge by sanding it around onto the top of the wing so it's blunter than when I recvd it from new. I now have a foil that is virtually silent which is amazing as it was really pissing me off! It was an absolute pleasure to be using ot the other day ??

So my advice is if the foils are thin in profile on the rear edge and quite sharp then try taking them back so they are blunter, I was using 240 wet&dry on the 45 deg then 400 and finishing it with 800

Good luck, hope u manage to get it sorted

I think the important thing mentioned in the Levitaz video is the change in angle as you sand the edge. A simple sharp, straight 45 degree edge can be just as noisy as a blunt trailing edge. I made a foil mast noisier when I sanded the trailing edge to be sharper. Following the Levitaz video fixed the issue.

The other trick is determining whether it's the mast, stabiliser or front wing causing the problem. It's not always obvious if you've just bought a foil and can't swap wings/stabiliser to work out what's the causing the problem. One solution is to put clear tape (e.g. Gorilla clear) along all the trailing edges with an overlap of a few mm. This creates a temporary, perfect trailing edge which should get rid of the noise. Then take the tape off each component one by one until the noise reappears.

Dspace said..

simonp65 said..
I think the important thing mentioned in the Levitaz video is the change in angle as you sand the edge. A simple sharp, straight 45 degree edge can be just as noisy as a blunt trailing edge. I made a foil mast noisier when I sanded the trailing edge to be sharper. Following the Levitaz video fixed the issue.

The other trick is determining whether it's the mast, stabiliser or front wing causing the problem. It's not always obvious if you've just bought a foil and can't swap wings/stabiliser to work out what's the causing the problem. One solution is to put clear tape (e.g. Gorilla clear) along all the trailing edges with an overlap of a few mm. This creates a temporary, perfect trailing edge which should get rid of the noise. Then take the tape off each component one by one until the noise reappears.

That's a neat idea on isolating the noise with tape. Definitely worth a try. Got my wet/dry sand paper in hand so some tweaking this afternoon and test rides/ retweaking tomorrow

Both my SAB/Moses masts (72 and 82cm surf) have been quiet based on using them with my quiet wings.

It would be cool if someone could come up with a preconfigured one-size-fits-all "noise reducing" trailing edge sanding profile block. Perhaps impossible wishful thinking

I just sand mine at 90 degrees. I use a wood block with brand new wet and dry, no water. Works every time.

simonp65 said..
I think the important thing mentioned in the Levitaz video is the change in angle as you sand the edge. A simple sharp, straight 45 degree edge can be just as noisy as a blunt trailing edge. I made a foil mast noisier when I sanded the trailing edge to be sharper. Following the Levitaz video fixed the issue.

We'll, I finally made some major improvement following your (Levitaz) advice, and doing it with the 220, 400, 800 progression.

I think my first time mistake was ending with 220 and not using 400/800 wet/dry to finish up, and not rounding off better. I had the trailing edge with a sharp 45, then finally squared off a bit using the 220 with a hard block.
So this time I resharpened the tip and trailing edge with 220, then rounded them off a bit with the 400 and 800 on a block. My final step was a light 800 sand with no block so it would conform to everything, including dulling/ rounding the very rear edge which I had just sharpened. Even went over some of the scratches elsewhere on the foil with the free hand 800. For whatever reason it worked great. Happy winger now Thanks!

The Levitaz method produces a Donaldson trailing edge which has some history and a bunch of research behind it.



www.seabreeze.com.au/forums/Stand-Up-Paddle/SUP/The-definitive-solution-to-fins-and-foils-whistling-humming--The--Donaldson-trailing-edge-

"The Donaldson trailing edge is characterized by a progressive smooth change in the slope of the trailing edge in the pressure side of the vane." iopscience.iop.org/article/10.1088/1755-1315/22/3/032045/pdf