Kayak Materials 101

There are a wide variety of materials used in the construction of kayaks. Choosing the right material depends on several factors including weight, durability, performance, and your budget. The three main types of materials used are polyethylene plastics, thermoformed plastics and composite materials (fiberglass, kevlar and carbon fiber).

Polyethylene Plastic

First used in the 1970’s for making kayaks, polyethylene plastic has revolutionized the paddling industry. The low price, and high impact resistance of polyethylene has made it the material of choice for many paddlers. Polyethylene kayaks are made using a process called ‘rotomolding’ where the polyethylene powder is put into a mold which is then heated and moved around. The heat melts the plastic and the movement ensures that the plastic is spread out evenly inside the mold.

Polyehtylene is the least expensive and heaviest kayak material. It is also the softest material used in kayak construction. This makes it flexible and therefore the most impact resistant material on the market. This softness also means that polyethylene kayaks can become deformed if improperly stored and paddlers may notice some flex while the boat is being paddled, thereby reducing efficiency in the water. The softness of polyethylene also makes it less abrasion resistant. Over time this will result in scratches to the hull which will increase drag and slow the kayak as it is paddled. The lower price makes polyethylene kayaks a good choice for a first kayak, but avid kayakers will usually opt for thermoformed, fiberglass, or kevlar.

Advantages:

  • Inexpensive
  • Excellent Impact Resistance

Disadvantages:

  • Heavier
  • Less abrasion resistant
  • Has more flex

Thermaformed Plastic

Thermoformed or polycarbonate plastics are your next step up in terms of weight, performance and price. They are constructed using two separate molds for the top and bottom of the kayak which are then assembled together and bonded with an adhesive.

When compared to polyethylene, thermoformed kayaks are lighter, have better glide, are stiffer and more abrasion resistant. As a result of their shiny finish and abrasion resistance, they have less drag in the water and feel more like a composite kayak when paddled.

When compared to composites they have a similar weight to fiberglass but are heavier than kevlar or carbon kayaks. While stiffer than polyethylene, thermoformed plastics are not as stiff or as abrasion resistant as composites. These kayaks are also tend to be less expensive than fiberglass.

Advantages:

  • Light weight
  • Moderately priced
  • Good glide
  • Good impact and abrasion resistance

Disadvantages:

  • More expensive than polyethylene
  • Not as stiff and abrasion resistant as composites

Composites

As the name implies composite kayaks are composed of two distinct materials; a cloth and a resin. The cloths most commonly used in composite kayak construction are fiberglass, kevlar (aramid fiber) and carbon fiber. Composite kayaks are also usually covered with an outer gelcoat to give them their color and an extra layer of abrasion protection. This gelcoat is not painted on but applied during the molding process. On some ultralight kayaks it is possible to apply a thinner clear coat instead of the gelcoat to save on weight, this generally makes them slightly less abrasion resistant.

Depending on the cloth used in a composite kayak the weight of the boat will change substantially. Fiberglass is the heaviest and least expensive option and is similar in weight to thermoformed plastic. Kevlar fabric has a higher strength to weight ratio therefore less cloth can be used for the same strength and the result is a lighter kayak. Carbon fiber with the highest strength to weight ratio is the lightest.

From a performance perspective composite kayaks are first to cross the finish line. They are stiffer than their plastic counterparts which means energy is more efficiently into the boat and less  is lost to flex. Composites also offer better glide and glide properties that are less likely to change over time due to scratches due to a higher resistance to abrasion. A scrape against a rock in a plastic boat will result in a deeper scratch than the equivalent scrape in a composite kayak. While composite kayaks are less impact resistant than polyethylene or thermoformed kayaks they are still quite durable and are very easily repairable.

Advantages:

  • Stiffer
  • Better Glide
  • Lightweight
  • Easily repairable

Disadvantages:

  • More expensive
  • Less impact resistant