sanding mast & foils - which grit to use

[mede]

Hey everyone

I would like to sand my mast and foils, in order to avoid ventilation and increase speed.
Did my online research, but did not find consensus on what is the best grit to use at what places on the foil and mast.

Older posts seem to favor 1000 - 2000 p, newer ones rather 400 - 800 p.

Recommendations? I'm also interested in the reasoning behind those.

Many thanks in advance,
Mathias

[evan]

LE > TE
Submerged surfaces 2000 - 1200 - 800
Breaching surfaces 800 -1200 - 2000 (top mast, wingtips)
all cross sanded 45deg and use a spraypaint base coat before sanding to fill any imperfections.

Big plans for trying to reach cavitation speeds of 55kn+ ( or did you mean ventilation?)

[Oldman]

LE > TE
Submerged surfaces 2000 - 1200 - 800
Breaching surfaces 800 -1200 - 2000 (top mast, wingtips)
all cross sanded 45deg and use a spraypaint base coat before sanding to fill any imperfections.

Big plans for trying to reach cavitation speeds of 55kn+ ( or did you mean ventilation?)

Can you explain what you mean by '2000-1200-800'?
Thanks

[evan]

LE of the profile 2000 grit, middle 1200, TE 800 for least drag.

The reverse for least ventilation on the surface piercing profiles, some even do a single perpendicular pass with even coarser grit just on the first cm of the LE to reduce the ventilation even further.

[mede]

Big plans for trying to reach cavitation speeds of 55kn+ ( or did you mean ventilation?)

Corrected, thanks

[mede]

LE > TE
Submerged surfaces 2000 - 1200 - 800
Breaching surfaces 800 -1200 - 2000 (top mast, wingtips)
all cross sanded 45deg and use a spraypaint base coat before sanding to fill any imperfections.

What is the source of your info? What is the rationale for going so fine for a start ? (on French forums, consensus seem to become to go more coarse for performance gains, finer more for looks)
Did you personally test this? If yes, with what methodology?

[evan]

This is what the Levitaz and their riders are using, winning almost all the big events last year so they must be doing something right

[kit3surfer]

Is it possible to sand too much - will I recognize this?
Are there risks to demage the carbon layers and what happens if yes?

[StellaBlu]

Is it possible to sand too much - will I recognize this?
Are there risks to demage the carbon layers and what happens if yes?

Im not a tech, but if it starts producing dark sanding residue you have probably gone too far. I say probably because I've also seen pigmented clear coat or filler that produces similar residue (which is still probably ok to sand). Someone suggested spraying additional clear coat on top in order to fill any imperfections, which I agree with, but it also gives you a little bit more surface to sand. Keep in mind, that this kind of sanding isn't to remove material - the purpose is just to finish the surface (hence the superfine grit).

[kit3surfer]

Thanks, and in case it becomes black dust, what is the consequence after stopping to sand of course. Will the carbon layer suck water and do I have to put on a kind of finish/spray afterwards or will it be also fine if I keep it like that?