Epic Introduces Measurement of Stiffness

Thursday, 22 June 2006 12:27 | Written by 
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ImageThe metrics commonly used to compare surf skis are length, width and weight. 


But it seems to be a commonly accepted fact that stiffness also affects a hull's performance.  A Google search resulted in a number of articles that had a common theme: if the hull flexes as you pull a stroke, energy is absorbed (and wasted) that would otherwise propel the hull forwards.


Epic just introduced a new measurement of stiffness in their skis: flexion.


In order for it to be useful of course, you need the equivalent measurements for all the skis for comparison.  Perhaps this is where Surfski.info could be useful!  We could take a range of skis and measure the flexion of each under the same conditions.


At any rate, Oscar Chalupsky sent us these photographs from the Epic factory in China.






The ski in the photographs is an "Ultra" lay-up example i.e. the lightest in the range and therefore the ski that you'd expect to have the most flexible hull.  The measurements were done with supports "about 5.5m apart" and with a 20kg weight in the cockpit.  The deflection on this ski was 7mm.  (The ski looks like a V10L; perhaps the V10 would flex less given the greater height of the foredeck?)


Oscar says that the Standard lay-up ski flexed 6.3mm and they expect the Economy ski to flex still less.


For the results of any comparison to be meaningful too, one would need to come up with some way of estimating the effect of flexion on speed.

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