Sea Kayak - Construction Materials

It can be said that modern materials of construction are the key to the growth of kayaking as a popular sport. In other words, if kayaks were still being made from wooden frames covered in animal hides, the sport would be very handicapped in popularity for a number of reasons including high cost, high maintenance, and animal rights issues. Instead, we see that kayaking is experiencing explosive growth in popularity.

Let's look at the different materials used and their advantages and disadvantages. These are listed in chronological order of appearance and development to emphasize the corelation between the newer materials and the kayaking sport's growth.

Generally only used north of the artic circle by die hard purists and out of sight of animal rights activists. Not an off-the-shelf item. Produced only by the paddler himself. Time consuming and expensive. Must be oiled regularly with natural oil such as seal fat.

A step up from wood and seal skin but still not a realistic choice for most paddlers. It is not an off-the-shelf item. Generally only produced only by the paddler himself. Weight is usually high making handling difficult and reducing payload. Time consuming and expensive to build. Difficult to repair. Limited life span for the materials.

This method is still used today, particularly on folding kayaks. The flexible fabric skin can aid in stability but may adversely affect speed performance. It is light weight and is the preferred material blend for most folding models. This method is, however, expensive and difficult to repair. The fabric also has a limited life span. Fabrics originally used were canvas but now more modern stronger fabrics are available.

Plastic kayaks are the least expensive and the most common. At the factory, pelletized plastic material is poured inside a mold and then heated and rotated in what is called a Roto-mold process. The plastic takes the shape of the inside of the mold. The process is challenging as cooling the plastic results in shrinkage and improper techique can result in warping and distortion. Yet, it is an inexpensive method to mass produce recreational kayaks. It is also used to produce some well priced sea kayaks too.

Polyethylene is robust but heavy, thereby limiting the boats performance compared to higher priced materials such as composites. UV inhibitors in the plastic give it a long life. The seats are often molded as part of the hull in some low end economy models and are non-adjustable. This one size fits all design reduces crew comfort and limits use to short range pleasure boating. Because of the disadvantages such as heavy weight and low strength, low grade polyethylene is generally not considered a good material for larger sea kayaks.

Higher quality polyethylene, however, is used successfully on a number of sea kayak models thereby making them a well priced option for many paddlers. Typically a polyethylene kayak is priced about $1000 less than a comparable thermoformed model and is about 8 lbs heavier. The surface finish of polyethylene is not as appealing as that of thermoformed or composite boats.

This is not to be confused with polyethylene material and the Roto-mold process. This method uses sheets of hybrid plastic materials wrapped around the outside of a mold. This material is stronger and harder than polyethylene. It has a glossy finish similar to fibreglass. It gives superior performance than polyethylene but is heavier than fiberglass or other composites. It is less expensive than composites but more expensive than polyethylene. It is very durable and long lasting. This method is very quickly becoming the method of choice for intermediate priced boats.

Composite means a blend of materials which are usually held together by a resin or glue. Plywood is actually a composite of woods. However, in the modern language sense "composite" is a all inclusive term that includes a number of newer materials including fiberglass, Kevlar and carbon fiber. These kayaks are built by applying sheets of the composite material over a gel coated mold. Then the sheets are coated in a bonding resin. Several layers are added for strength, ridgidity, puncture and tear resistance. The last outer layer of gel coat on an exterior mold gives a very smooth glossy surface.

The result is a boat hull that is both light weight and very very strong. Fibreglass units are about 20% lighter than a similar polyethylene boat. Kevlar and carbon are even lighter still. These materials and the method of manufacture make these boats the most expensive. They can be repaired with little weight penalty after suffering even serious damage.

Which Kayak Material is Best?