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Old 15 December 2011, 09:30   #11
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Very good!
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Old 18 December 2011, 12:37   #12
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See this, interesting thread from another forum:
Golf ball boat - install a dimple plate? - Boat Design Forums
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Old 18 December 2011, 18:25   #13
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Osmosis in the mould
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Old 19 December 2011, 08:55   #14
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lookin at it, it should reduce wetted surface area, though i'm not sure about the trade off with all the edges causing extra friction and reduction in laminar flow?
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Old 20 December 2011, 04:15   #15
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A golf ball spins and this won't.

Water will follow the hull and flow into the dimples as there won't be a sharp edge to separate the flow from the hull.

Making it would also be a nightmare.

I'm sure someone would of tried this before and if it worked we would see this everywhere.
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Originally Posted by Zippy
When a boat looks that good who needs tubes!!!
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Old 20 December 2011, 04:32   #16
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Quote:
Originally Posted by jyasaki View Post
I seem to recall an America's Cup yacht using a similar surface (though much smaller dimples), maybe 20 years ago?
If memory serves, 1200 grade sanding of the Gelcoat on an Oppie was about optimum - even smaller dimples! Granted speed through the water is somewhat less, but that theory does seem to scale down based on the three part heresay we have generated here.

I vaugely remember it being described as it setting up lots of small circular motion elements of water, thus essentially creating a "rolling" layer a bit like pushing something along on a floor covered in ball bearings. Perfectly smooth the laer of water beside the hull is in sheer, so energy wasted doing that. How that scales up to a rib at 40 knots I'll leave to the hydodynamicists.....
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Old 20 December 2011, 04:41   #17
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Boundary layer.
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Old 21 December 2011, 15:58   #18
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Quote:
Originally Posted by Cookee View Post
A golf ball spins and this won't.

Water will follow the hull and flow into the dimples as there won't be a sharp edge to separate the flow from the hull.

Making it would also be a nightmare.

I'm sure someone would of tried this before and if it worked we would see this everywhere.
Cookee - that seems a somewhat blinkered view to possible innovation. Everyone told James Dyson that if there was a better way to make a vacuum cleaner Hoover and Electrolux would have found it. Given, as you say, the complexities of making loads of dimples in a hull, that actually fluid dynamics are not as well understood as many people think especially when air, water and solids all interact and that a lot of boat building and design has been about gut feel and trial and error rather than computational models - even if someone thought it might work, that doesn't mean they would have turned it into reality with the right size dimples distributed in the right pattern etc.

Although the idea has been known about for years in golf balls, its only relatively recently that people have started to apply the concept to aircraft: How golf ball

Of course there may be downsides to it too, and any advantage (if there is any) may not justify the cost increase from complexity of production for either average or high performance users, especially compared to other approaches like steps / scallops etc.
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