If you were to apply super-hydrophobic coating to the hull of ships or even submarines, would you get more or less water friction?

If the coating completely repels the water you could argue there would be even more friction as it pushes the water out of the way rather than have water stick to it. But perhaps this is not the case as the repelling of the water might be less turbulent and so might decrease friction, and that ships would be able to travel faster with less fuel required.

  • $\begingroup$ How would being water-repellent increase friction? If your ship is less "sticky", it's going to be dragging less water around with it. $\endgroup$ – David Richerby Nov 30 '14 at 21:54
  • $\begingroup$ @DavidRicherby there could be more complicated reasons at play that some one might know better than I. On initial thought it sounds obvious, but when is science ever that straight forward. $\endgroup$ – Dave Nov 30 '14 at 23:13

I did some research and it seems that superhydrophobic coating can be used to decrease drag forces to a certain extent because the coating repels the water. It creates an air layer between the surface and the water that causes slip through two-phase flow. This allows the ship to slip past the water.

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  • $\begingroup$ When you say "to a certain extent" does that imply theres a tipping point where it is no longer effective and worsens the situation ? $\endgroup$ – Dave Dec 1 '14 at 0:41
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    $\begingroup$ Could you cite some of that research? $\endgroup$ – pentane Dec 1 '14 at 13:30

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