Author Topic: Paddle Blade Coatings for a Race?  (Read 1994 times)

ukgm

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Re: Paddle Blade Coatings for a Race?
« Reply #15 on: September 19, 2018, 09:43:29 AM »
The size of the grooves is matched to the density of the fluid (water in our case) and the speed of travel so that the grooves dampen the turbulence of the water as the flow detaches from the hull.”

Absolutely. ..... and this is for watercraft that are typically operating at 13-15kph. SUP's are lucky to get to 10 so you can imagine how relevant that probably isn't when compared to other factors at that point (such as addressing theoretical maximum hull speed).

Note: We use 'trips' and changes in surface texture on our skinsuits in cycling now to do the same thing. I've got a time trial suit designed for 40kph and another for circa 40kph that I use (depending on the kinds of courses I might be racing over..)

PonoBill

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Re: Paddle Blade Coatings for a Race?
« Reply #16 on: September 19, 2018, 05:44:45 PM »
Dolphins have tiny lateral grooves in their skin that vibrate with muscle movement to mitigate wall drag. Sharks do a similar thing with their denticles, which are a lot more prominent. Dolphin skin also seems to shed bacteria and fungus by its microstructure. Nothing much grows on a dolphin.
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Pierre

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Re: Paddle Blade Coatings for a Race?
« Reply #17 on: October 01, 2018, 03:52:50 AM »
Boundry layer, also called limit layer, laminar, turbulent, means a lot... purpose is to get it as thin as possible.. on a paddle blade I guess purpose is NOT to take water out with it.
on a hull, 400 to 500 sand paper... many other solutions here...and finally!!!   https://www.gp14.org/a-smooth-bottom-is-a-fast-bottom/
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yugi

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Re: Paddle Blade Coatings for a Race?
« Reply #18 on: October 01, 2018, 08:26:03 AM »
^ Yep.

The article’s conclusion is spot on:
“In the end, it’s not that complicated. Your appendages should be as smooth and fair as possible, and your hull should be just as flawless in the forward areas. Aft of where you expect transition on the hull (certainly by amidships), the surfaces need only be “hydrodynamically smooth.” Finally, when faced with the myths, remember the no-slip condition.”

Thanks for the link, Pierre. Fun, because I was at Brown with Paul Grimes but no longer sailing undergrad regattas.

After that I was mostly in board sailing (and traction) sports. Where I quickly learned first-hand that when planeing no one cares about the “boundary layer” on their boards.

More relevant at our (SUP) speeds, but still technique, ability and fitness still count so much more that it’s practically irrelevant.
« Last Edit: October 01, 2018, 08:28:35 AM by yugi »

 


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