I recently had a repair done on a foil and it left parts of the foil with more resin and a rougher finish. I’m pretty sure that sanding the excess down will help, but does polishing it make a difference? I would assume it could reduce drag, but don’t really know if it’s something worth exploring.
Any of you have tried it?
Waste of time
You might get minor difference speed , but most of it will be in you head
You polish when it’s time to sell at a swapmeet. People like the shiny straight from the factory look when buying. Sanded to a hydrophilic finish is better for daily performance.
There are different theories as to what grit is better (800 through 3000), but the general consensus is that a shiny polished surface is bad. I’ve been happy with about 2000 grit.
How do you acheive a hydrophobic finish? I might try to use the mentioned 2000 grit and call it a day
Hydrophobic finish is bad.
Sanded finish is good.
If water drops bead on foil then degrease (alcohol is good,do not use cleaners with silicons etc..) .
If it still beads then sand.
I use 1000 wet,but lots of different opinions on this.
PS : I once cleaned the foil with KH7 , a general cleaner-degreaser.I was generous with it 
It must have some silicon,wax or whatnot because the foil was almost unrideable afterwards, draggy,high stall speed,unpredictably twitchy.
Had to come in and clean it with acohol.
Hydrophobic is factory finish or polish finish. You don’t want your foil scared of water though.
Hydrophilic is very easy to get and you can tell when your foil gets wet and stays wet instead of beading up and kicking the water off. I pretty much only sand using 2000 grit and rarely go higher or lower.
Here’s an under 60 second repair with a hydrophilic finish:
Before:
One ultra thin clearcoat to fill in the scratches (takes5 seconds) and then a quick sand at 2000 for 30 seconds.
What clear coat do you use?
do you coat the entire wing or just a spot?
As recommended by a local shaper:
Entire wing is best for as much damage as that foil had. Sometimes you can get away with a small spot but it’s easier to spray the whole thing evenly and then sand the entire thing evenly.
I didn’t have time to properly sand a foil once after repairing it. Think I ended up sanding it with 300. It was a dock start foil and it was almost impossible to start with. Felt extremely draggy and difficult to control. Once I sanded it down to 600 it felt pretty much like it did before. Haven’t tested how much of a difference going to 1000 or 2000 does compared to 600 but nowadays I always sand down to at least 1000 to be sure.
This is insanely helpful. I wing in an area where hitting debris below the surface is common. Do you have any tricks for restoring the trailing edge of foils? Super small less than 1mm deviations along the trailing edge.
@TooMuchEpoxy I’ve been meaning to respond but here we are with a related thread.
I try to avoid rebuilding the trailing edges because whatever I use to fill them in usually isn’t the same hardness as the carbon. As such, sanding gets wacky and imperfect which causes problems.
With the clear coat you for minor scratches you are just spraying it on and then sanding it back off so I have minimal concern about changing the shape of the foil.
Sanding trailing edge is tricky to get it right.
But if I had to do it, I would make 1/8" cut out in the broken area, stick a clear plastic tape on the underside of the wing, fill the cutouts with wetted-out carbon strand, use my finger to mash them fuzzy and finaly put a clear tape on top of it all. You can then sand it back to the original shape.
Hope it help!
