What Are Whitewater Rafts Made From?

The material a raft is made from affects its handling through major hydraulics.

Today's inflatable whitewater rafts are primarily made from either polyester or nylon coated with a waterproof plastic or synthetic rubber material. The most common of these coatings are Hypalon, urethane and PVC. Each material has its own advantages and disadvantages, based on intended usage, handling on the water and the climate in which the raft will be used.

Base Fabric

The base fabric provides puncture and tear resistance, with coatings applied for air retention, durability and resistance to abrasion. Nylon fabric tends to be stretchier yet stronger, while polyester stretches less but has a lower tear strength.

Hypalon

This synthetic rubber coating is most frequently used over nylon, which is also lined with neoprene. Highly durable and resistant to harsh environments, this type of raft is used in military and rescue operations and for harsh whitewater environments.
Advantages: high air retention, resists mildew, UV deterioration and chemicals damage. Hypalon rafts usually have twice the usable life of PVC rafts
Disadvantages: Hypalon rafts are usually much more expensive because of the fabric preparation necessary. Seams need to be butted and glued by skilled technicians to prevent separation during use. The end product is less rigid and more flexible on water, which may cause the raft to be harder to handle and hang up on objects more frequently than its PVC counterparts. Professional repair is necessary if tears or leaks develop because of the several layers of material and coatings.

PVC

PVC (polyvinyl chloride) coating is a vinyl-based material similar to Hypalon in UV resistance. Lighter in weight and stiffer than Hypalon, PVC rafts are more maneuverable in rapids and hang up less on rocks because of being slicker and more rigid than Hypalon counterparts.
Advantages: Seams can be thermobonded at the factory, resulting in extremely strong molecularly bonded seams. Glue repairs are easily done using Stabond. Affordable because of the simplicity of materials.
Disadvantages: Stiffer material makes rolling up the raft more challenging. PVC material can crack when rolled or stored in cold environments. Plasticizers leach out over time, leaving the raft brittle and the material weakened.

Urethane

Not as common as PVC or Hypalon boats, Urethane is appearing more in top-end rafts due to its light weight and durability.
Advantages: Similar in durability to Hypalon while providing slick maneuverability like PVC. Lightest of the three coatings where weight may be a factor. It can be used by itself as a sealer or applied over other coatings. Can be thermobonded like PVC
Disadvantages: More expensive than PVC. More difficult to weld or glue than PVC, increasing repair expense.

Other Material Facts

Three other factors contribute to the strength of the inflatable raft; denier, fabric weight and thread count.
Denier refers to the weight in grams of one thread 9000 m long. The more it weighs, the higher its denier will be. Most quality rafts have a minimum of 420 denier, with commercial-grade rafts having a denier of more than 1000. Thread count refers to the number of threads per inch and fabric weight is the weight of one square yard of the base material. As with denier, a higher number indicates a more durable fabric.

References

• "The Complete Whitewater Rafter"; Jeff Bennett; 1996
• The Don Casey Library: Inflatable Boats
• NRS: Hypalon and PVC Inflatable Boat Repair

Resources

• The Don Casey Library: Inflatable Boats
• "The Complete Whitewater Rafter"; Jeff Bennett; 1996