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It is all about boundary layers which are major players in determining friction between moving and static surfaces. As a surface moves through a medium (air or water), there will be a layer of the medium that will move with the moving surface (static layer). Father away from the moving surface will be layer where the flow is laminar. In between the static layer and the laminar layer is the turbulent boundary layer. Dimples on the golf ball make the boundary layer thinner and therefore reduce aerodynamic friction and the ball flies farther. Americas Cup sailboats have a "rough" surface, much likes sharks, that thins the boundary layer, reducing hydrodynamic friction and the boat sails faster.
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gary
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