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Inflatable Boat Materials

Inflatable boats use several different types of hull materials and production processes. Over the years, there has been much discussion and much controversy on the pros and cons of each material and each production process. Generally speaking, the production process used is tied to the material being used. Here is a summary of major different materials and production processes used and a summary of the pros and cons of each:

Unsupported PVC

Used by Sevylor, Sea Eagle, Intex & others, this type of material is made from an unsupported PVC film - there is no fabric. It is generally used on the least expensive inflatables and the quality and durability varies greatly Quality and durability of an unsupported inflatable boat is determined by the formulation and the thickness of the PVC material being used. Generally, the thicker material and the higher quality of the material the stronger the hull material and the longer its durability. There is a molecular weight standard that is used in the evaluation of unsupported PVC, which ranges from K-60 to K-85 material. Often this value is not published by the manufacturer, but the higher the molecular weight, the stronger and more durable the material will be. This type of material is almost always die-electrically welded (this process uses very large welding machines with large dies).

Advantages:

  • Extremely economical as a material
  • Extremely fast and economical manufacturing process
  • Equal tear strength in both directions, making long tears less likely
  • When welded properly, extremely durable & long-lasting
  • Very forgiving because it operates at a lower PSI (.75 psi).
  • More abrasion resistant because it is a solid material

Disadvantages

  • Can be quite weak and not very durable when using the nylon/polyester sewn fabrics and & unsupported PVC
  • Can be quite expensive when using best materials (i.e. 1000+ denier polyester with urethane bladders)
  • Can be prone to sewing problems
  • Can be subject to “poor fit” problems – i.e. where bladder or outside chamber is smaller, larger or not properly adjusted for a proper fit.
  • Less able to take a motor because of lack or rigidity
  • Because bladder system boat use both an inside and outside hull, water often gets in between the 2 layers and adds significant weight to the boat. This can also pose difficult cleaning problems

Supported Polyester Fabric with PVC coating

(Used by Zodiac, Sevylor, Sea Eagle, Mercury Inflatables & others) – This type of material has a polyester fabric with an outside PVC coating. This is the most widely used material for supported fabric inflatable boats because of its relatively economical material and production cost. It also has a reputation of being more susceptible to UV radiation, salt water and chemicals.

The quality of this type of hull material depends greatly on the quality of the PVC coating used and whether is calendered (brushed on as a top and bottom layer) or laminated (composed of 3 layers outer film coating, fabric middle and inside film coating).

Generally speaking, the calendaring process is far more reliable adhesion process than the laminating. The chemical make-up of the outer material is also extremely important – it must have additives specifically for sunlight and chemical resistance.

Advantages

  • Economical production system
  • Flexible production system – can be either welded or glued.
  • Economical hull material – far less expensive than hypalon nylon or hypalon polyester
  • Very strong and puncture resistant.
  • Can be inflated at quite high air pressures for good rigidity
  • Extremely durable & long-lasting
  • Capable of being used in the roughest white water or handling large outboard motors

Disadvantages

  • Can be subject to a “brown & sticky” problem – when using a PVC coating that has not been formulated to be resistant to sun, salt water and chemicals, the material can become over time “brown and sticky”. This is where the plastifiers have migrated from the PVC and the material can be attacked by bacteria. This generally does not occur in “good” formulation PVC coatings.
  • When welded, it can be, if not done properly, can be subject to delamination of the seam.
  • When glued in an environment where the temperature and humidity are not controlled, the seams can be weakened in spots and become defective
  • When welded or glued in an environment where there is dust or dirt, the seams can be weakened and become defective.
  • Less able to take a motor because of lack or rigidity

Supported Nylon or Polyester Fabric with Hypalon coating

(Used by Achilles, Avon, Caribe & others) – Hypalon has the advantage that it is generally more resistant to sunlight and chemicals, but it has the disadvantage that it far more expensive as a material and the production process is more costly because the 2 part glue used requires a longer layup time (time between applying the accelerant and being able to apply the glue) – this makes the production process for this type of material far more costly. It is also not capable of being welded.

Advantages

  • Very strong and puncture resistant
  • Very resistant to sunlight and chemicals
  • Can be inflated at quite high air pressures for good rigidity
  • Extremely durable & long-lasting
  • Capable of being used in the roughest white water or handling large outboard motors

Disadvantages

  • Very expensive material
  • Very expensive to manufacture
  • Cannot be welded
  • When glued in an environment where the temperature and humidity are not controlled, the seams can be weakened and become defective
  • When welded glued in an environment where there is dust or dirt, the seams can be weakened and become defective.