TomW wrote: ↑
Wed Apr 25, 2018 10:00 pm
Just round those sharp corners in the outline. They are non functional and catch water.
TomW as in TW surfboards?
It's a twin tip I'm designing, not a surf board. If I wanted drag from the coander effect then I'd redesign it. The rounded end board tapers from the top so it doesn't induce coander effect. (hard under side corners)
Conventional hull boats have smooth sterns and speed limitations. Planing hulls have sharp sterns and can go much faster.
I suggest you look up the coander effect so you can resolve our difference of opinion.
Here's a link showing the effect over a spoon: https://www.youtube.com/watch?v=AvLwqRCbGKY
From the moment a stream of water starts flowing along a surface, that stream will be resistant to separation from the surface while the path over the surface is smooth. Any trailing edge of a kite board will entrain water around curves, more so with soft curves.
By breaking up the perimeter of my board I'm also breaking up the flow of water where it would otherwise stick to the rail(smooth rail outline) or flow around the back and up (rounded under edges.)
I believe this effect is used on parts of the sides of surfboards intentionally for grip but I'm avoiding it on purpose in my last two designs.
Makes it easy to fit kwila rails too