Thursday, October 05, 2017

Everything On The Inside... Brought To You By US Blanks (Pt. 5: Rocker)

Everything On The Inside
brought to you by...
US Blanks

Rocker Selection
by David Scales, US Blanks

We’ve been hosting a tutorial series detailing how to select the precise correct blank for your surfboard build. It’s easy to pick a blank that works, but our goal with this series is to find a blank that generates the least amount of physical waste while allowing you to focus on fine tuning the details such as contours, subtle curves, foil, channels, etc. In past lessons we’ve covered Foam Selection, Density Selection, Blank Size Selection, and Stringer Selection. Today we will focus on Rocker Selection.


Rocker is the amount of rise in the Nose and Tail, as measured from the bottom plane of the blank. In other words, it’s the curve that you can see from the profile view of the blank. Rocker is a vital element when considering board design. Rocker is a highly influential component of speed and turning radius. The basic hydrodynamic principles to consider here are:

1) Lesser Rocker (i.e. flatter) = More Speed
2) More Rocker (i.e. curve) = Tighter Turning Radius

Your goal is find the right amount of flatness to allow maximum speed, but then the right amount of curve to control that speed through turns. One design consideration is that these two features contradict one another. When a board is tracking straight along the water’s surface, that upward curve in the Nose pushes water. Pushing water slows the forward momentum. However, once you turn the board on it’s side and the rail line is in the water, that curve will naturally lead the board through a turn. The more curve in the rail line, the tighter the turning radius.
So again, the goal with Rocker Selection is to select the right combination of flatness and curve for your desired speed and control (i.e., turning radius). Every board design has a different ideal Rocker based on the other design components, the surfer, the specific waves where the board will be ridden, and a variety of other variables. 
Every US Blanks blank is engineered with a “Natural Rocker” that is designed
to meet the widest variety of needs for that blank’s style. For example, our Shortboard
blanks have increased Nose rocker to accommodate for high-performance surfing
whereas our Fish blanks have flatter Nose rocker to accommodate for speed in smaller


The Rocker is written as an equation (using the Imperial System). That equation is written as, the amount of rise in the Nose, followed by the amount of rise in the Tail, as measured from the bottom plane of the blank. Let’s use the 6’4” EA as an example:

Natural Rocker 5 1/2”N 2 1/6”T

This indicates that the tip of the Nose is raised 5 1/2” and the Tail is raised 2 1/16” from
the bottom plane of the blank.


In an effort to allow you to find your exact desired Rocker, we allow for Rocker Adjustments. These adjustments are always written as adjustment from the Natural Rocker and are always adjusted from the center unless otherwise specified. For example, if you wanted your 6’4”EA with increased Nose rocker and increased Tail rocker, you might order:

+1/2”N +1/8”T

This indicates a 1/2” rise in the Nose and a 1/8” rise in the Tail, above the Natural Rocker.


You may want a “flipped tip” in the Nose of a shortboard or an excessively rockered Tail for a noserider while maintaining flatness through the middle of the board. For this we allow Rocker adjustments to be made from locations other than center. This is indicated by number of inches from the tip of the Nose or Tail. For the equation, that number is located right after the adjustment height. For example:

+1/2”N18” +1/8”T12”

This indicates a 1/2” rise above the Natural Rocker, but only in the last 18” of the Nose. And a 1/8” rise above the Natural Rocker in the tail, but only in the last 12”.


To recap, the exact right Rocker for your build can only be determined by you. If you’ve carefully selected the right blank for your build, then the Natural Rocker of that blank will likely suit your needs. However, should you feel that you need an adjustment to the Rocker to fulfill a design concept, we can certainly accommodate you. Again, the more precisely we can deliver a blank to you, the less wasted foam and the more you can focus on fine tuning the details of your designs.

US Blanks Rocker Templates

No comments:

Post a Comment

Thanks for checking out our blog and sending comments. Stay tuned!

The Foam E-Z Crew.