Surf Show and Tell: Comparison of Varial Foam vs PU

 

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The quantitative results you have been waiting for are finally here. Noel Salas did a comparison of two identical boards:

 

– Both were a Channel Islands Sampler 5’7” x 19 x 2 5/16”.

– One made with a standard polyurethane foam (PU) blank containing a wooden stringer, and the other with stringerless Varial Foam.

– Both boards were glassed polyester resin and with single 4 oz fiberglass cloth on the top (S Glass) and bottom (E Glass).  Salas used Traceup data to compare the performance of the Varial Foam board to the PU board, while also filming each test session.

– The testing, which was performed at Lower Trestles, was recorded over a period of 3 sessions with Salas riding each board for half his session, and alternating which one he rode first.

 

The results of the testing were intriguing, and we learned a lot about what makes one board outperform another. The testing showed the average speed of the PU was 5% faster, but the Varial was significantly faster and more powerful in cutbacks.  The Varial cutback power was 16% greater compared to the PU and the cutback rotation speed was 8% faster.  It is impossible to separate average speed from wave height, so the average speed difference could very well be due to larger waves being caught on the PU board.  However, the fact that faster and more powerful turns were made on the Varial Foam board, in perhaps smaller waves, reveals a significant performance difference. We were able to notice this difference in watching the video footage of Salas surfing these boards.  It looks to us the Varial Foam board is displacing a lot more water in turns, and is carrying more speed during the change of direction in a cleaner, tighter arc.

 

Varial had an 8% greater cutback turn angle compared to the PU core, however the cutback roll angle (degree the board is on rail) of the PU was 5% greater. This seemed counterintuitive to the cutback speed and turn angle being greater.  What we suspect is happening is that the faster you go through a turn the more centripetal force you have pushing the board horizontal.

 

To put all of this into context, let’s break down a cutback.  The duration (or total time) of the cutback was about equal between the Varial Foam and PU boards.  The difference the data shows is that during those cutbacks Salas had significantly more speed and power on the Varial, which allowed him to travel in a more complete arc and then exit the turn going faster. In a judged format this type of turn would likely score higher based on WSL’s speed, power, and flow criteria.

 

The results for bottom turns favored Varial. Even though the bottom turn speed gain percentage of the Varial was the same as the PU board, the bottom turn roll angle degree (amount of rail in water) was 14% higher. The bottom turn duration of the Varial was also 4% longer but the vertical degree after a bottom turn was 1% higher for PU.  Salas commented that he felt he could push harder on the Varial, which may explain why the roll angle was greater.

 

Overall this experiment was very interesting and by far the most scientific study that has ever been carried out to show the difference between two technologies in the same shape.  Noel Salas is an excellent and very consistent surfer, which makes him the ideal person to do this type of study.  We owe him a huge thanks for all the hard work he put into this effort and for helping consumers better understand Varial Foam.  We look forward to working with him more and fine-tuning the process to further minimize experimental variables such as surfer fatigue, wave height differences, and differences in surface conditions.  Stay tuned for more studies to come…