Sanding my wing is safe?

[abel]

My 633 wing lost the transparent glossy look on the part that you see the carbon fibers on top of the wing and it felt kind of rough,... like the fibers were sticking out a bit. It was not abrasion given that its a part that doesn't touch sand and it was exactly on the shape contour of the grafics
I sanded it and painted with thin layer of yacht varnish.
Looks good and not feeling any issues while riding.

[cor]

I sanded it and painted with thin layer of yacht varnish.

I think you missed the topic of this thread here. If you varnished it after, you lost every advantage of sanding a foil.

[Michaelr123]

I sand my race foils and use a variety of paper but finish with 1200 or 1500 but different water needs different grit to be stable, fast and performant. I also tried sanding my moses onda surf foil but i just sanded the bottom surface so the top still looks nice, not sure it made any difference to the ride, maybe a little, it was ventilating quite a bit due to some scratches etc before I sanded it. I used 800 grit wet and dry paper on the moses.

Derek,

if you don't mind me asking, how do you determine what grit to use for the water condition? is it a salt/fresh water situation or is it more complicated than that? I never would have thought that really small changes like sanding grit or wing size and shape changing by 50cm^2 would make that much of a difference, but now that I've experienced it first hand I totally get it, it's like having a tuning fork running through the water.

[derek440]

Yeah when you first start out everyone thinks it won't make a difference but the surface that is supporting everything is vital especially when you are putting lots of force through it. There are loads of theories about sanding and which water for which paper, mostly I listen to others and use trial and error. Personally I tend to lean towards using easier paper to work with like 800, but now I am spending more $ on my foil I am reluctant to cut into it too much so am using finer paper like 1200 on my race foil but have only ever used 800 on the moses 633. Another thing with race foils is that now they often come race sanded which is the case for my latest foil the levitaz R5 with that foil I am just cleaning it carefully after every use and putting it back in the covers, one of the things with sanding is when you have the foil working well (almost no ventilation and stable and good feel) then you just clean it and keep it the same until somethings changes.

As an interesting side point at the recent foiling world championships the craftsman who makes the worlds other fastest foil - the Chubanga V3 was there in a boat sanding foils for the top pros between races! Crazy.

[JoseTumaco]

I sanded it and painted with thin layer of yacht varnish.

I think you missed the topic of this thread here. If you varnished it after, you lost every advantage of sanding a foil.

Thanks Abel for that information, can you explain why varnishing makes loosing the advantage of sanding? You mean thant it is not necesary to do anything else after sanding?. Thanks.

[cglazier]

Jose
Long before kiteboarding, sailors discovered that lightly sanding the hulls and rudders of their boats reduced the drag and increased their speed. This worked. Now all kiteboarding racers know to sand their foils to maximize performance. But it is an active discussion as to exactly which grit of wet sandpaper to use and just how best to do it.

For refence it is similar to the reason golf balls are made with dimples rather than being smooth.

In my opinion many (probably most) recreational kiteboarders will not notice much difference.

But be assured that there is no need to reapply a glossy finish to your foil after a repair. The glossy finish on new foils is just about appearance, not performance.

CG

[tomtom]

Golf ball is wrong example and very often used. Ball is one of least aero/hydro/dynamic shape. Dimple make flow around more turbulent to mitigate shape resistance. It doesnt work same way on streamlined and especially laminar profiles. Also sanding hulls is mostly anecdotal and not scientific proven. Sportsmen have lots of habits to help them win - lots of them are woodoo. There was article about this from expert aerodynamic engineer from lockheed martin but im lazy to find it. Sanding may work but from different reason than dimples on golf ball

[Flag53]

I’m just wandering if anyone has actually measured before and after “ Full foil sanding “ to see what difference it makes to actual speed

[Matty V]

If you have to ask the question if it’s safe, then no probably not

The variations of suggestion are indexation that’s it’s best left alone or you are highly likely to bugger up a decent foil.

You are better off keeping it clean and free of finger prints, grease and sun cream

[plummet]

What i dont think has been discussed here is the possibility of you sanding the wing too much and thus removing carbon, exposing the core and damaging the foil.

This is a particular risk around trailing and leading edges.