The core material of your surfboard—Polyurethane (PU/Poly) or Expanded Polystyrene (EPS/Epoxy)—makes a massive difference in how the board performs, influencing its momentum, responsiveness, and durability. Choosing the right construction is critical for optimal surfing.
Key Takeaways & Tips
PU/Poly (Heavier & Settled)
PU is the standard construction and is heavier. It tends to settle more in the water, offering a damp feel that is good for absorbing vibration. Due to its weight, once you stop paddling, the board continues to glide, maintaining momentum longer.
EPS/Epoxy (Lighter & Responsive)
EPS is more buoyant and lighter, making the board more responsive. This is excellent for smaller waves, as the lightness and buoyancy provide more flotation. However, once you stop paddling, the board stops quickly, lacking the glide/momentum of PU.
Flotation Adjustment
EPS floats more than PU. If you want the same float as a PU board, you should order the EPS board about 1/16th of an inch thinner in the same dimensions. This makes the boards feel about the same in buoyancy.
Advanced Use Case
EPS is used mainly for smaller wave performance shortboards to add responsiveness and flotation. PU is used with heavier density for bigger boards (guns, longboards) to provide stability and durability, and to help them get down into the wave.
EPS Sensitivity
EPS can be chattery in windy conditions and doesn’t hold as well on turns as PU. This is due to its buoyancy, which keeps it above the water more. EPS also takes on water quickly if dinged, requiring immediate repair.
Common Mistakes to Avoid
Ignoring Durability
Not accounting for EPS’s durability drawbacks. EPS is more heat sensitive (keep out of the sun) and takes in water much quicker than PU if damaged. You must get out of the water as soon as possible if you get a ding.
Riding EPS in Wind
Riding EPS boards on windier days. The board’s lightness and buoyancy can cause it to become chattery and negatively affect turn hold due to being easily unsettled by surface chop.
Not Adjusting Paddle Stroke
Assuming EPS has the same momentum as PU. Because EPS is lighter, you must adjust your technique and paddle stroke to be more frequent, as the board stops gliding once you stop paddling.