The fastest board surface possible with DIY

[plummet]

On a technical note. The velocity required to obtain turbulent flow and create the boundary layer must be dependant on surface roughness.

So...

Surface roughness needs to selected based of speed of the craft.

Too much roughness will yield too much drag and slow your board down.

Not enough roughness will mean the laminar flow will still prevail at board surface.

[KerryBara]

What about coating the board with this stuff

http://www.spillcontainment.com/ever-dry

Check out youtube clip, pretty amazing stuff

[downunder]

Thanks guys

I like the coating idea as well.

Cheers

D.

[Eurus]

F1 cars aren't designed to be aerodynamic. They are designed for down force because they are fast as f*** and need to be pushed into the track to improve traction.

[downunder]

I'm a proud Razor owner and probably the only one in Perth

And just watching this:



Looks like the rough surface IS a go.

Will see in a few weeks time after I finish my board and compare with a production one:)

[Kamikuza]

F1 cars aren't designed to be aerodynamic. They are designed for down force because they are fast as f*** and need to be pushed into the track to improve traction.

Above certain speeds, they produce enough down-force go overcome gravity and could be driven on the ceiling...

[Kamikuza]

I'm a proud Razor owner and probably the only one in Perth

And just watching this:



Looks like the rough surface IS a go.

Will see in a few weeks time after I finish my board and compare with a production one:)

Be an easy DIY project to make a Razor... Should be cheap too, there are plenty of windsurf fins lying around at the clubhouse!

[downunder]

The core already built

Will be a bit smaller tho! Watch this space

[fogmeister]

why are they roughing only one side of fin and what would happen if both sides of fin were rough?

[BWD]

They sand both sides of the fin, from LE to maximum thickness.
The part from the thickest part of fin back to TE is not sanded, as sen on kf tv.

The point is to roughen the most curved parts of the foil enough to trip the boundary layer of water so it makes turbulent flow over more of the surface, because turbulent flow tends to stick to a foil surface better than laminar flow, which sticks perfectly in a perfect world, but as soon as a bubble, strand of seaweed, bad chop, sneeze, or whatever happens, it totally detaches causing a spinout and crash.
It's interesting they choose 150 grit sandpaper.
The amount of roughness has to match the size of the foil and the speed range.
For example for a board or planing boat surface, higher grit is used, typically 300 to 1200. Has to do with water viscosity, object size and shape, etc.
Some people also do this with surfboard fins, I believe with lower than 150 grit.
This is because the surfboard fin is even smaller, lower AR and lower operating speed....
This stuff is pretty cool to learn about.

BTW if you did sand only one side, it would be the low pressure side, since that is where the flow detaches causing spinout.
But this wouldn't make sense for a symmetrical foil sailed on both tacks, since both sides see high or low pressure from tack to tack.