Equipment Series > Bodyboard Cores

Author: Derek Footit
14th April 2008

Part #1: Bodyboard Cores

When searching for a new bodyboard, we are often faced with brands advertising materials which we are not familiar with, using abbreviations or trade names for types of cores, deck skins, slick skins etc ... But what do they stand for, what do they do and which one is right for me?

The materials used in the construction of a bodyboard play a very important role in the performance of your board and hence your performance on it. It may be your riding style, your physique, the wave types you ride or water temperatures which suit one bodyboard or material over another.

So here's what we plan to do - over the next few months we will try help give you a better insight into the construction of your equipment.

In part 1 we cover the types of cores available; essentially there are two main core types - Beaded and Extruded - with Combination cores being a mix of the two.

A. BEADED CORES

Beaded cores have a cell structure like a white Polystyrene cooler box. Small beads are put into a mould and heated until the beads expand to fill the mould. The core is then stored to allow it to cure and let gasses escape. Beaded foams are more expensive than extruded foams due to the cost of raw materials and the time to make each core. The cell structure of beaded foams creates a stronger material compared to extruded cores, but when flexed return to their original shape slower than extruded foam. This recoil effect, referred to also as memory, is the dynamic which provides the projection out of a bottom turn - greater recoil effect = greater projection.

Pros:

* Greater Stiffness
* Product longevity
* Water Resistance
* Less Rocker Distortion
* Popular warm water core

Cons:

* High Price
* Prone to Denting
* Less "Recoil Effect"
* Less Floatation
* Can be too stiff in really cold waters, dependant on personal preferences

B. EXTRUDED CORES

Extruded foam is made in long sheets and is cut to size by the manufacturer. Extruded foams contain "air" bubble cells. Chemicals are mixed by large machines and then forced out an opening mixed with a chemical that infuses the "air" bubbles. The cost to make extruded foam is far less expensive than beaded foam due to the speed of manufacturing and cost of raw materials.

Pros:

* Lower Price
* Increased Floatation
* Dent Resistance
* Greater "Recoil Effect"
* More control
* Less bounce
* Softer landings
* Popular cold water core

Cons:

* More flexible
* Rocker Distortion
* Prone to cell damage and water absorption
* Can feel heavy in small waves
* Can be too flexible in warm waters, dependant on personal preferences

C. COMBINATION CORES

Combination cores are made by laminating two or more different materials together. A combination core can be made using a layer of extruded foam and a layer of beaded foam or the same type of material, but with different densities.

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The following are some of the most popular cores:

1. POLYETHELENE (PE)

Core Type: Extruded

Polyethylene cores give you more control due to the core being more flexible and forgiving, it is a perfect core to be used in cold water when coupled with stiffeners such as the modern day stringers and high quality slick skins. The reason for the PE Core being more forgiving is purely because of the fact that there is more flex in the core and will cushion a lot of the blow on landings of big aerial moves and heavy take offs. The recoil is amazing, but the core is prone to deck lift if left in the hot sun or car or deck sink just from heavy abusive riding. The PE Core is slightly heavier than a PP Core but can give a lot better recoil in cold water. A PE Board, if looked after well, will last as long as the PP Board and at a cheaper price can be better value for money.

1.a. Extruded Polyethylene (EPE)

Core Type: Extruded

Commonly known as DOW or PE cores, this has been the dominate core material since the invention of the Bodyboard. PE is relatively inexpensive and is readily available. But since the EPA changed the laws regarding chemical emissions several years ago the strength of the material has decreased and thus the life of the high performance board, which spawned the development of stiffeners like stringers, intermediate stiffening layers of foam, and other materials.

PE is the core of choice for entry level boards offering a good price to performance ratio. PE is also excellent for cold water conditions, since low water temperatures increase the stiffness of all cores.

Boards of 40 inches and under are small enough to remain stiff without the help of a stringer, resulting in good performance for small riders. Since PE contains air bubbles it is soft to land on when doing aerial manoeuvres. PE is very dent resistant but as pressure is constantly applied to the same location the "air" bubbles will break down causing a mushy feel to the area. Water absorption is caused when the cell structure of the "air" bubble is damaged by either constant impact or cuts exposing open cells.

1.b. Crosslink

Core Type: Extruded
Generic Name: High Density Polyethylene (HDPE)

This is a High Density Polyethylene Core. That just means that the foams construction consists of super tiny bubbles compared to that of the normal construction of a PE Core. From that you would assume that this would make it heavier, but actually it's as light as a PP Core and is waterproof. The best qualities of the Crosslink Core is that it's as light as PP and rides like you're on a PE Core -- the best of both.

This core is light and fast with enough flex to handle heavy airs. It does get elbow dents quite easily and will start to get rocker after months of punishment, however, it can be forced back into shape.

2. POLYPROPYLENE (PP)

Core Type: Extruded or Beaded

Also known as PP or POLYPRO, this core is available as either beaded or extruded. This is creating some confusion in the market since the material Polypropylene will follow the rules explained regarding extruded and beaded cores. The main advantage of Polypropylene is Memory - the material has superior retention of its original shape - and remains water resistant longer than most cores. Lightweight Polypropylene has an excellent strength to weight ratio.

2.a. Beaded Polypropylene (BPP)

Core Type: Beaded

A beaded Polypropylene core will not dent as much as Arcel but will follow the same rules of beaded cores, less Recoil Effect (memory), Cost, etc.

2.b. Extruded Polypropylene (EPP)

Core Type: Extruded

Extruded Polypropylene is made from strands of Polypropylene and follow the same rules for extruded cores, but it has better memory or enhanced Recoil Effect.

3. ARCEL

Core Type: Beaded
Generic name: Expandable Polyethylene/Polystyrene Interpolymer

Arcel has not been around for a long time, but we'll cover it as it gives you a bit of history of what was at one time a very common core. Arcel is a beaded core which started to show up in the late 80's as a high performance core material due to its superior strength over PE. Arcel will maintain its rocker and stiffness giving you about twice the performance life compared to PE especially in warm water.

The main draw back of Arcel is it will dent particularly where your elbows contact the deck and where drop knee riders put there knee. The dents are viewed differently by each rider. Some like the indentation at the elbows because it helps to keep there arms from slipping off the board.

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For the next instalment we'll be covering the different Deck Skins!

Please feel free to contact me for impartial, no obligation advice.

Derek Footit
Factory 7 Online Board Shop

0800 FSEVEN (0800 373836)
+27 (0) 39 315 6698
www.factory7.co.za

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