Dynamic plank measurements

In my practice sailing in Żnin I was testing two full carbon masts. One each day. Both seem to be on a soft end of the range. My feeling was that my plank has a lot to do with how the mast performs.  When I studied my action cam recordings I felt I need to make dynamic load measurements of the plank.  This measurement was done last time long time ago so I had to find all accessories hidden in the boxes covered by dust. 

DN runner plank dynamic load measurement
DN runner plank dynamic load measurement

The setup is very simple. One important notice: apply tension/load with system built of non-stretchy materials. In my case steel cable connected to hunters’ digital scale and to dyneema wrapped around the plank.  

I used headstay adjuster to precisely apply load. The laser range finder fixed to the tripod was delivering precise continuous reading of deflection. Reading of deflection was taken after every 10kg load added from 0 to 120kg. 

Simple graph below shows interesting results:

DN plank dynamic deflection chart
DN plank dynamic deflection chart

Orage represents the plank that I was using for testing the masts. In some load range it is up to 10% stiffer than the other plank. I think I found the answer to my question. I should go with blue plank instead of orange.

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