The dimples on a golf ball "delay separation of the boundary layer from the ball. Early separation, as seen on a smooth sphere, causes significant wake turbulence, the principal cause of drag. The separation delay caused by the dimples therefore reduces this wake turbulence, and hence the drag."

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Has windsurf gear ever used dimples, either on a sail, fin or board?
I'm giving it 1 hour before someone says "back in the nineties..."

Yes, Back in the nineties ....Angulo boards from Mauii had dimples.

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Herbylyn said...

Yes, Back in the nineties ....Angulo boards from Mauii had dimples.

The dimples were pretty large,small size dimples like on a golf ball covering the bottom of the hull would be interesting although it would be a bugger to make.

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choco said...

Herbylyn said...

Yes, Back in the nineties ....Angulo boards from Mauii had dimples.

The dimples were pretty large,small size dimples like on a golf ball covering the bottom of the hull would be interesting although it would be a bugger to make.

Nah. Ever heard of a ball pien hammer?

I'm still hanging out to see the board with the shark skin finish, and the whale bumps on the fin.

Called a "phaser" if I remember correctly back in the nineties

So... they didn't work as intended,
even though they made it through R&D, testing and production?

They were called "phaser" bottoms and they were a production item for a small time on the angulo boards and one or two other brands, circa 1989-1992.

I had a couple of prosail boards with phasers in them. Cant remember if they actually did any thing or just looked crazy for their time.

Yeah !!

I had a fluro Red, Green and Yellow Asymmetric wave scalpel with about 30 x 10cm phasers on the bottom ( back in the 90's)

And they did absolutely nothing Guess I bought into that gimmick


MG.

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evlPanda said...

So... they didn't work as intended,
even though they made it through R&D, testing and production?

Are you sure you want to open that can of worms?

I believe that there is a bigger picture that we, the end users, are not seeing. In a hundred years, it will all make sense. Trust in the manufacturers, my son.

the theory doesn't apply to us- spheres yes foils no. They would have better been applied to angulo wave boards as producing a cushioning effect, increased surface area (lift) & possibly increased skin strength.

I used to have a Morey Boogie board called The Mach 8TX which had weird golf ball dimples on it!

Dont think it made that much difference but was only a boggie board so not excatly high performance!

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morph said...

I used to have a Morey Boogie board called The Mach 8TX which had weird golf ball dimples on it!

Dont think it made that much difference but was only a boggie board so not excatly high performance!

OI! Are you slagging off Boogie Boards now????? Wanna make something of it???

I recall from my Biomechanics days that the purpose of the dimples on a golf ball is to lower the "Reynold's number" of the ball.

The resistance a projectile experiences is proportional to its velocity squared.

However, as a projectile goes faster, there is a point in its velocity when resistance suddenly becomes proportional to velocity (instead of velocity squared)

ie- velocity suddenly becomes considerably less!!

The velocity this occurs at is known as "Reynold's critical number". This number is different depending on the projectile and can be altered by varying the properties of the projectile (shape, mass, surface texture etc).

The dimples on the golf ball have the affect of lowering Reynold's critical number, so the advantage gained by less resistance is easier for average golfers to attain.


In windsurfing terms, it's a bit like how as the board goes faster, it experiences increased resistance (slogging) until it reaches planing speed. Suddenly when planing, the resistance is way less. We can vary the characteristics of a board to make planing occur at a lower velocity. (weight, volume, width, fin etc)

Once planing, the wind can drop, yet we can often keep the board planing due to the much less resistance we're experiencing, compared to the poor bugger next to us who is just trying to get started in the same amount of wind!

Believe it ...... or not

was there something about using wet and dry on the hull to increase speed?

My first board was an Ulladulla custom. Jsut a floater with a 6m sail for my 55kgs at 15. Wish I had kept it. It had dimpes all over the bottom......but I think this was due to being driven around on roof racks in a hail storm. I really don't think that it was faster than a flat bottom board.