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Old 4th June 2008, 10:45 PM   #9
Dream Team - School Guru
Join Date: Aug 2006
Posts: 2,177

Hi windfrancois,
I think the current wisdom on "surface finishes" for windsurf gear/hi speed sailing dinghys/huge racing yachts is that a polished surface is too smooth and actually cuts down your speed.
Using a "figure 8" pattern with 400 wet/dry abrasive cloth is about the best you can do.
Some folks like a straight pattern in line with the water flow.
The idea is to create a little "tooth" (microscopic maybe, but "tooth" just the same) to hold a boundary layer of water molecules on the surface.
Testing has shown that water has less "friction" on a fully wetted out boundary layer than on a polished surface with no boundary layer or "wet out".
Surface finish can have a positive effect on preventing spin out, but mostly spin out
is due to imperfections in either the foil or the planform of the fin.
Hope this helps,
Roger is offline   Reply With Quote