Understanding Ply orientation for surfboard deck

I was reading about a surfboard called “Futue flex”, it uses a quad axial glass fabric for lamination. I understand this means one of each 0, 90, 45 and -45. I have some questions:

1‌) Would it matter if I used UD 0,90,45,-45 or if I used woven 0,90 and +45,-45. My question how would it differ if I used UD vs woven, I understand that UD has less crimp and less resin rich regions, does it also have any effect on the mechanical properties?

2‌)‌ If I understand correctly, 0 & 90 are used for longitudinal and transverse stresses, what are ±45 used for?

  1. If quadaxial lamination common practice for surfboards?

less crimp= slightly higher stiffness and higher elastic limit. But the main advantage is a noticeable better fatigue strengh.

Multiaxis allow a better spread of stress under foot pressure, around rail against impact too.

Not a standard, easier to go with clear plain open wave surf glass

I think Stretch is doing some 0-90 and 45-45 ‘controlled flex technology’ on production boards: http://www.stretchboards.com/construction/


A very smart guy who used to post around here did some qualitative testing of various laminate schedules to include the use of Innegra along with various fiberglass weave orientations.  If I recall correctly, he posted a chart that indicated a fairly substantial advantage to ‘backing up’ a normal 90 degree weave cloth with a 45 degree weave.  I believe in his testing that the addition of the additional weave direction sort of ‘filled in’ the gaps between strands that are left when using a straight 90 degree fabric.  His destructive testing process proved this to be the case.  

If you do a search for Benjamin Thompson you might still be able to find some of his stuff.  He also did some interesting research on flex analysis.

This is the sort of stuff you can expect when science nerds start getting involved with surfboard design and contruction…  https://www.youtube.com/watch?v=HopUXYfW9zs




In answer to question #3: no, quadaxial lamination is not common practice in the industry. 

This is not because it isn’t a good idea, but rather because user-friendly fabrics have not been available until very recently (meaning narrow rolls of glass with +/- 45 orientation in ~4 oz. weight and that are stitched so the fibers don’t twist and move around as soon as you touch it).  

Again—-  Plain Weave E or Warp combined with Vector Net.   One under and one over or just one over.  Very good.

1 - woven fabrics are easier to drape on a surfboard contour. 2 layers are easier to work with than 4 layers. differences in mechanical properties will be a small factor for a surfboard.

2 - 45’s will stiffen the ‘twist’ 

3 - common practice is just 0/90 farbic with more fibers in the 0 than the 90 (this is called ‘warp’)