Contact   Imprint   Advertising   Guidelines

Happy Foil Has Grainy Finish

A forum dedicated to Hydrofoil riders


User avatar
NYKiter
Very Frequent Poster
Posts: 1668
Joined: Fri Mar 22, 2013 9:17 pm
Kiting since: 2010
Style: Wave
Gear: .

Happy Foil Has Grainy Finish

Postby NYKiter » Sun Jul 30, 2017 1:50 pm

Seems to go against the grain of everything needing to be super-polished and smooth to reduce drag....if wetting the surface is faster why dont they all do it?..anyone have any info on this surface?

User avatar
davesails7
Very Frequent Poster
Posts: 1983
Joined: Sun Apr 01, 2007 7:36 pm
Kiting since: 2006
Local Beach: Virginia Beach
Style: Race
Gear: Delta Hydrofoil and Board
Flysurfer Sonic2 9m,11m,15m,18m
OR Mako 130x35
Brand Affiliation: None

Re: Happy Foil Has Grainy Finish

Postby davesails7 » Mon Jul 31, 2017 9:55 pm

If it isnt vibrating and you're not racing I wouldn't worry about it.

My spotz 2 had a very inconsistent finish, as many of them did. Not smooth, a bunch of pinholes. I painted it with primer and sanded it so it was nice and smooth. It rode much smoother after that

NorCalNomad
Very Frequent Poster
Posts: 742
Joined: Thu Feb 13, 2014 4:40 am
Kiting since: 1900
Local Beach: San Francisco
Gear: Why should it matter?

Re: Happy Foil Has Grainy Finish

Postby NorCalNomad » Tue Aug 01, 2017 3:04 am

Not a race foil, and cheaper to leave a rougher surface

User avatar
davesails7
Very Frequent Poster
Posts: 1983
Joined: Sun Apr 01, 2007 7:36 pm
Kiting since: 2006
Local Beach: Virginia Beach
Style: Race
Gear: Delta Hydrofoil and Board
Flysurfer Sonic2 9m,11m,15m,18m
OR Mako 130x35
Brand Affiliation: None

Re: Happy Foil Has Grainy Finish

Postby davesails7 » Tue Aug 01, 2017 4:32 pm

NorCalNomad wrote:
Tue Aug 01, 2017 3:04 am
Not a race foil, and cheaper to leave a rougher surface
Its not expensive to smooth the finish. A can of rustokeum filler-primer and a pack 600 grit wet-dry sandpaper is only $15. It does take a few hours of time though.

NorCalNomad
Very Frequent Poster
Posts: 742
Joined: Thu Feb 13, 2014 4:40 am
Kiting since: 1900
Local Beach: San Francisco
Gear: Why should it matter?

Re: Happy Foil Has Grainy Finish

Postby NorCalNomad » Wed Aug 02, 2017 8:53 pm

davesails7 wrote:
Tue Aug 01, 2017 4:32 pm
NorCalNomad wrote:
Tue Aug 01, 2017 3:04 am
Not a race foil, and cheaper to leave a rougher surface
Its not expensive to smooth the finish. A can of rustokeum filler-primer and a pack 600 grit wet-dry sandpaper is only $15. It does take a few hours of time though.
That right there is $$$

Mossy 757
Very Frequent Poster
Posts: 1182
Joined: Fri Sep 11, 2015 5:10 pm
Kiting since: 2013
Local Beach: First Landing State Park, Virginia Beach Oceanfront
Style: Kitefoil
Gear: Delta Hydrofoil and board. Cabrinha Velocity 9m, Flysurfer Sonic2 11m, Elf Joker-7 15m

Re: Happy Foil Has Grainy Finish

Postby Mossy 757 » Wed Aug 02, 2017 9:54 pm

It's possible that grainy finishes provide a microgeometry for delaying boundary layer separation. It's almost certain that the Happy Foil wasn't designed with this in mind. It was reported once on here that Maxime Nocher was spotted roughing up the trailing edge of his Banga foil strut at a regatta because it was having some issues ventilating along the strut. Not sure if that's related to boundary layer separation, but either way the jury is still out, I believe, on the best way to finish a foil.

All of that basically amounts to, "if it ain't broke don't fix it," but maybe more so, "if it ain't broke AND you're not actually measuring performance metrics relative to other competitors, don't fix it."

It's nice every year to tune up your gear, and mass produced foils could almost certainly benefit from some careful tweaking, but I agree that spending the time to really obsess about the surface finish probably won't produce a positive ROI.

borist
Frequent Poster
Posts: 469
Joined: Tue Apr 20, 2010 12:30 am
Kiting since: 0
Brand Affiliation: None
Location: San Diego, CA

Re: Happy Foil Has Grainy Finish

Postby borist » Thu Aug 03, 2017 12:56 am

If wings are made from G10 it makes sense. G10 is not to easily machined to mirror like surface. If even possible, then not cheap. It is layered material and subtle curves like on HF wing make this even harder. My Spitfire wings are a bit on the rough side. Add scratches and nicks, they look like they need major overhaul. However foil rides as good as new. :lol:

User avatar
NYKiter
Very Frequent Poster
Posts: 1668
Joined: Fri Mar 22, 2013 9:17 pm
Kiting since: 2010
Style: Wave
Gear: .

Re: Happy Foil Has Grainy Finish

Postby NYKiter » Thu Aug 03, 2017 2:17 am

Actually the mast and fuse are textured as well...

dylan*
Very Frequent Poster
Posts: 790
Joined: Sat Mar 26, 2016 4:33 pm
Kiting since: 2011
Gear:
Brand Affiliation: None
Location: Florida

Re: Happy Foil Has Grainy Finish

Postby dylan* » Thu Aug 03, 2017 10:47 pm

borist wrote:
Thu Aug 03, 2017 12:56 am
If wings are made from G10 it makes sense. G10 is not to easily machined to mirror like surface. If even possible, then not cheap. It is layered material and subtle curves like on HF wing make this even harder. My Spitfire wings are a bit on the rough side. Add scratches and nicks, they look like they need major overhaul. However foil rides as good as new. :lol:
happy foil wings are carbon

BWD
Very Frequent Poster
Posts: 3139
Joined: Thu Jun 05, 2003 3:37 am

Re: Happy Foil Has Grainy Finish

Postby BWD » Fri Aug 04, 2017 1:24 am

I wouldn't mess with the finish on the spitfire.
To work a canard needs specific stall tendencies on each wing, that envelope is abit more uncommon and less obvious than the front wing lifting, rear wing pitching dynamic in conventional foils. The exact shape, and the surface on the canard may or may not be more important to it working right.

Nocher definitely knows what he's doing. To say the least.
But. Tweaking the trailing edge is normally done because it's the easiest way to reduce vibration in any blade/fin/foil in fast sailing. In general, by the TE there is little or no laminar flow, and not too well attached flow on the high pressure side, definitely not the low pressure side (turbulent is the adjective there).

Surface roughness on the low pressure side, especially upstream of max thickness, delays flow separation and turbulence.
Blunting trailing edges, or making them just sllghtly assymetrical on a symmetrical (mast) foil can reduce resonance/vibration from vortex shedding. Synched up vortex shedding from both sides of a symmetrical foil will cause larger oscillations in pressure at the TE leading to excess drag and ventilation/crashing of a surface piercing foil (mast). Excess resonance from same is the cause of loud humming foils, also draggy.

Grainy finish all over in conventional foil? It's just cheap. Smooth it out if you don't like how it rides.


Return to “Hydrofoil”

Who is online

Users browsing this forum: jaros, Peter_Frank, qdwhaty and 4 guests

cron