Contact   Imprint   Advertising   Guidelines

Sanding foils? Trying to understand why and how?

A forum dedicated to Hydrofoil riders
richy-c
Medium Poster
Posts: 51
Joined: Wed May 16, 2018 7:48 pm
Kiting since: 2007
Local Beach: Ainsdale, Cleethorpes, Rhosneigr, Los lances Tarifa. Mar menor Murcia, El Medano Tenerife
Gear: Best Kites. Shinn boards, North Boards
Brand Affiliation: None
Has thanked: 7 times
Been thanked: 2 times

Sanding foils? Trying to understand why and how?

Postby richy-c » Sun Apr 28, 2019 3:34 pm

I hear that some guys are sanding carbon foils. Why is this please?

Matteo V
Very Frequent Poster
Posts: 1180
Joined: Mon Mar 20, 2017 3:42 pm
Kiting since: 2008
Local Beach: US, Iowa/Nebraska/Kansas/Utah/Oregon Coast
Favorite Beaches: Ft. Stevens, North coast of Oregon
Style: Just like school in summertime
Gear: Delta Kites and LF Kitefish QuadMod
Snowboard (Cambered and Rockered)
Foil kites on the snow
Brand Affiliation: NONE F--- the corporate world
Has thanked: 20 times
Been thanked: 49 times

Re: Sanding foils? Trying to understand why and how?

Postby Matteo V » Sun Apr 28, 2019 9:35 pm

Catamaran sailors, for a time, thought that a mirror smoothed surface creates more drag than a flat (fine grit sanded) one. While the principle is soundly based in physics, actual use mostly showed no significant differences.

There may be some additional "cavatation (not real vacuum cavatation)" issues with a hydrofoil that a sanded surface may help with. But again, you are more likely to get a placebo effect, than a real one.

richy-c
Medium Poster
Posts: 51
Joined: Wed May 16, 2018 7:48 pm
Kiting since: 2007
Local Beach: Ainsdale, Cleethorpes, Rhosneigr, Los lances Tarifa. Mar menor Murcia, El Medano Tenerife
Gear: Best Kites. Shinn boards, North Boards
Brand Affiliation: None
Has thanked: 7 times
Been thanked: 2 times

Re: Sanding foils? Trying to understand why and how?

Postby richy-c » Sun Apr 28, 2019 10:10 pm

:thumb:
Matteo V wrote:
Sun Apr 28, 2019 9:35 pm
Catamaran sailors, for a time, thought that a mirror smoothed surface creates more drag than a flat (fine grit sanded) one. While the principle is soundly based in physics, actual use mostly showed no significant differences.

There may be some additional "cavatation (not real vacuum cavatation)" issues with a hydrofoil that a sanded surface may help with. But again, you are more likely to get a placebo effect, than a real one.

User avatar
gmb13
Very Frequent Poster
Posts: 1407
Joined: Wed Sep 12, 2007 10:19 am
Kiting since: 1999
Local Beach: Flag Beach, Fuerteventura
Style: Everything
Gear: Ozone, Axis, Moses, Zeeko, Firewire, SBS
Brand Affiliation: Foiling Basics, The Boardroom Fuerteventura, Ozone, Axiskiteboarding,Schwerelosigkite, Triggernaut,
Location: Fuerteventura
Has thanked: 3 times
Been thanked: 19 times
Contact:

Re: Sanding foils? Trying to understand why and how?

Postby gmb13 » Sun Apr 28, 2019 10:17 pm

It's mainly to reduce ventilation.

Basically, if you are not racing and you are not having issues with your foil ventilating, you do not need to sand it.

--
Gunnar

Matteo V
Very Frequent Poster
Posts: 1180
Joined: Mon Mar 20, 2017 3:42 pm
Kiting since: 2008
Local Beach: US, Iowa/Nebraska/Kansas/Utah/Oregon Coast
Favorite Beaches: Ft. Stevens, North coast of Oregon
Style: Just like school in summertime
Gear: Delta Kites and LF Kitefish QuadMod
Snowboard (Cambered and Rockered)
Foil kites on the snow
Brand Affiliation: NONE F--- the corporate world
Has thanked: 20 times
Been thanked: 49 times

Re: Sanding foils? Trying to understand why and how?

Postby Matteo V » Sun Apr 28, 2019 11:56 pm

gmb13 wrote:
Sun Apr 28, 2019 10:17 pm
It's mainly to reduce ventilation.

Basically, if you are not racing and you are not having issues with your foil ventilating, you do not need to sand it.

--
Gunnar
What is the best indicator of ventilation? Do you have to see it, or do you just feel it?
These users thanked the author Matteo V for the post:
gmb13 (Mon Apr 29, 2019 7:36 am)
Rating: 10%

User avatar
jakemoore
Very Frequent Poster
Posts: 1717
Joined: Tue Jan 20, 2004 3:59 am
Kiting since: 2004
Gear: Foil and 1strut kites.
Brand Affiliation: None
Location: Oleander
Has thanked: 24 times
Been thanked: 52 times
Contact:

Re: Sanding foils? Trying to understand why and how?

Postby jakemoore » Mon Apr 29, 2019 12:52 am

It can help a lot to reduce the noise if the hydrofoil sings.

User avatar
jakemoore
Very Frequent Poster
Posts: 1717
Joined: Tue Jan 20, 2004 3:59 am
Kiting since: 2004
Gear: Foil and 1strut kites.
Brand Affiliation: None
Location: Oleander
Has thanked: 24 times
Been thanked: 52 times
Contact:

Re: Sanding foils? Trying to understand why and how?

Postby jakemoore » Mon Apr 29, 2019 12:54 am

Matteo V wrote:
Sun Apr 28, 2019 11:56 pm
What is the best indicator of ventilation? Do you have to see it, or do you just feel it?

User avatar
gmb13
Very Frequent Poster
Posts: 1407
Joined: Wed Sep 12, 2007 10:19 am
Kiting since: 1999
Local Beach: Flag Beach, Fuerteventura
Style: Everything
Gear: Ozone, Axis, Moses, Zeeko, Firewire, SBS
Brand Affiliation: Foiling Basics, The Boardroom Fuerteventura, Ozone, Axiskiteboarding,Schwerelosigkite, Triggernaut,
Location: Fuerteventura
Has thanked: 3 times
Been thanked: 19 times
Contact:

Re: Sanding foils? Trying to understand why and how?

Postby gmb13 » Mon Apr 29, 2019 7:50 am

Matteo V wrote:
Sun Apr 28, 2019 11:56 pm
gmb13 wrote:
Sun Apr 28, 2019 10:17 pm
It's mainly to reduce ventilation.

Basically, if you are not racing and you are not having issues with your foil ventilating, you do not need to sand it.

--
Gunnar
What is the best indicator of ventilation? Do you have to see it, or do you just feel it?
Both and also sound. The first indicator is the that your foil will loose the grip on the water. It feels like a spin out on a windsurfer. You can also see if you look at your mast as it happens. You can also hear it. It's a sucking noise.

Contrary to popular belief, all Foils ventilate at some point. The difference between a well designed and well sanded foil is what happens after the ventilation starts. On a good foil the air does not propagate down the mast to the wings, and it stops almost instantly and the water reattaches to the mast. On a badly designed or badly finished foil the air will propagate all the way down to the wing, which leads to you crashing.

--
Gunnar

User avatar
gmb13
Very Frequent Poster
Posts: 1407
Joined: Wed Sep 12, 2007 10:19 am
Kiting since: 1999
Local Beach: Flag Beach, Fuerteventura
Style: Everything
Gear: Ozone, Axis, Moses, Zeeko, Firewire, SBS
Brand Affiliation: Foiling Basics, The Boardroom Fuerteventura, Ozone, Axiskiteboarding,Schwerelosigkite, Triggernaut,
Location: Fuerteventura
Has thanked: 3 times
Been thanked: 19 times
Contact:

Re: Sanding foils? Trying to understand why and how?

Postby gmb13 » Mon Apr 29, 2019 7:52 am

jakemoore wrote:
Mon Apr 29, 2019 12:52 am
It can help a lot to reduce the noise if the hydrofoil sings.
It can, but mostly the singing comes from a "dirty" trailing edge. If your foil sings loudly, then fix the trailing edge first. There are lots of tutorials online on how to do this.

--
Gunnar
These users thanked the author gmb13 for the post:
revhed (Mon Apr 29, 2019 10:50 am)
Rating: 10%

cor
Medium Poster
Posts: 129
Joined: Thu Apr 10, 2014 1:20 pm
Kiting since: 2007
Gear: -
Brand Affiliation: None
Has thanked: 39 times
Been thanked: 9 times

Re: Sanding foils? Trying to understand why and how?

Postby cor » Mon Apr 29, 2019 2:31 pm

jakemoore wrote:
Mon Apr 29, 2019 12:52 am
It can help a lot to reduce the noise if the hydrofoil sings.
+1

Sanded mine and noise is reduced drastically. But that wasn't the reason for me. It had scratches that I wanted to get rid off.


Return to “Hydrofoil”

Who is online

Users browsing this forum: Baidu [Spider], kuit, mar menor, matanshapira and 3 guests

cron