Does anyone know of any windsurf design that has incorporated riblets in the design of the hull of a windusrf board.
I've seen a few boards with dimples like that of a golf ball but none with ribs.
In aerodynamics riblets can give around an 8% reduction in in skin friction drag (which accounts for around 50% of total drag).
I think this increases even more for hydrodynamics.
Some studies have been done on shark scales that give the same effect as riblets, i'll try to find it.
Something for you speed sailors?
i think this topic has been done before?
not sure about riblets on windsurfers but the 12's where trialling them for the americas cup 20yrs ago.i think 25 said he trialled them as well but i am not sure of the facts on that ,he could elaborate. i seem to recall a comment of the film (3m) peeling off at speed...
The topic may have been done before. Probably by me!
I seem to remember something about the 3m tape.
I was just wondering if anyone knows if it has been applied to a windsurfer?
I had a Seatrend "accelerator" in the late 90's. It had a sparse pattern of very slightly raised pimples over the bottom of the board.
I think the idea is to trap a boundary layer of fluid (in our case, water) that actually moves with the board, reducing skin friction. Don't know if it worked.
I'm pretty sure Stars 'n Stripes used skin from 3m on its hull when it whooped Kookaburra 11 in Freo in '87 that was supposed to do it too.
I think windsurfers have used a matt finish rather than gloss with the same aim.
Didn't like the look of the bottom of the Seatrend!
i remember seeing a waveboard with half a dozen golfball styled dents in the bottom in front of the fin box, it looked like someone had taken a goldball and pushed it against the board while the resin was drying. the board also had a sticker on it stating it was constructed using hexcell, whatever that means?
The riblet idea came to mind again after they were talking about it on the telly regarding the olympic swimsuits.
Would be great to get hold of some of that 3m tape and give it to the GPS boys and see if you could tell a difference.
How about re-spraying the bottom of a board while there are a couple of silicone soaked rags lying around the paint booth?
Instant riblets.. Okay, more Orange Peel than riblets, but the effect would be similar?
Back in 1987 after the America's Cup had returned to the USA, 3M contacted the Gaastra ADTR R&D team based in Southern California. We were interested in testing the riblets on a board to see if there was any advantage for speedsailing. The riblets used on Stars and Stripes were designed to work in the 6-10 knot speed range, what we were looking for was a design range around the 40 knot mark. 3m ran the numbers and produced some film for us to test. Initially there was a speed gain of a few percent, we did the testing side by side and with some speedwatches, but when you span out it was almost impossible to recover without stopping. We put this down to the leeway angle exceeding the angular range the riblets would work in before before the flow dettached. Also after a few runs the riblets got debris embedded in them and the drag increased. We never went to tank testing as there didn't seem to be much potential in the idea. We also tested some solutions that could be applied to the boards to reduce drag but these were not that effective. I wrote a report and published the data in Windsurf magazine. Since then there has been more development with polymers and coatings for boats which do seem more effective. I have run some of them on my Trimaran and speedboards to good effect.
Try some of the Interlux paints that have teflon added and also Nautical Ease works well on both the Tri and the speedboards.
Thanks for that Roo.
I'm sure some of our GPS boys would be dying to get a few more knots out of their boards.
Do you have a soft copy of the board magazine article?
