Neoprene was developed during WWII as a practical replacement for natural rubber. It is truly a miraculous product, displaying most of the desirable properties of natural rubber and correcting a few of the negative ones. Neoprene is as elastic as rubber, much tougher, not as photodegradable, and it resists heat, hydrocarbon fuels, and many chemicals that turn natural rubber into a sticky goo.
When three chlorine atoms are added to the neoprene molecule, we get Hypalon, which retains most of the desirable qualities of neoprene with a dramatic increase in toughness and resistance to abrasion. It is even less vulnerable than neoprene to photodegradation, and it is less thermoelasticmeaning it won't soften when you leave your boat out in the hot sun. On the down side, Hypalon doesn't hold air quite as well as neoprene, and it's harder to glue.
The original inflatable dinghies introduced in this country by Avon and Zodiac were made from fabrics impregnated with neoprene and Hypalon. The Avons used Hypalon on both sides of the fabric. Zodiac used Hypalon on the outside, where abrasion resistance was most important, and neoprene on the inside, where airtight qualities were paramount. Today Avon maintains the same construction techniques as in the original boats while Zodiac has switched to the new kid on the block, polyvinyl chloride.
Polyvinyl chloride is a modern plastic. Record albums were made of it, and it’s the insulation around household electrical wire. We encounter this polymerized synthesis of acetylene and hydrochloric acid on a daily basis. There are problems with PVC and inflatable boats.
The PVC used to construct inflatable boats is the same material used to make plastic drain pipes, with one difference. Several plasticizers are added to the PVC that fabricates the boats airtight, soft and flexible, and dyes attain different colors. Plasticizers, while used to make rigid boats flexible and soft, are also destabilizing. Some PVC boats are remarkably more durable than others that came from the same manufacturer, but made with a different batch of material.
PVC has two major advantages over Hypalon fabric. One is that PVC seams are thermoelectrically welded quickly by machines run by semiskilled workers. Hypalon, or Hypalon and Neoprene fabric seams are painstakingly glued together by hand, by skilled workers. The savings to the manufacturer are passed on to the consumer because the cost of labor is lower. Thus, the second PVC advantage is cost. PVC inflatable boats are a lot cheaper than Neoprene and Hypalon.
However, PVC is difficult boat material. It’s highly photodegradable, meaning prolonged direct sunlight breaks it down. Cracks start to appear, the boat becomes less flexible, and eventually leaks air through the fabric. Many PVC manufacturers add an ultraviolet ray protectant, similar to UVA (ultraviolet absorbers) to paints and varnishes, but the long-term effectiveness is questionable.
The welded seams of a PVC inflatable are undeniably strong, while seams of fabric attached to wood, like the transom or flooring, are weaker than Hypalon, because they aren’t adaptable to cold glue, which makes the repair of punctures and tears difficult.
PVCs also have damage occuring from hydrocarbon fuels, and other chemicals.
The gasoline won’t eat through your inflatable, but it does stain, and shorten the fabrics life. Hydrocarbons and other various chemicals don’t affect Hypalon, proven by the usage in liners for chemical and fuel tanks.
In the Caribbean, I asked about a dozen full-time living aboard sailors and their families about PVC dinghies. The negative answers were startlingly emotional. Stories of dinghies falling apart in two seasons, and those who had purchased one, unanimously declared angrily they will never buy another. The manufacturers quickly, willingly, replaced the damaged boats with new ones.
Three recent surveys on PVC inflatable boats were in accordance with the Caribbeans. They were taken by the World Cruising Survey, Practical Sailor magazine, and Seven Seas Cruising Association. The results of all three were the same. Over 90% of the participants preferred Hypalon over PVC. All agreed also in choice of manufacturer, Avon or Achilles, giving Avon a three-to-one advantage.
Despite this information, consider buying a PVC inflatable boat. Surprised? All the surveys were conducted among people who dwell or spend a lot of time in the tropics. It’s a harsh environment for inflatable boats. Not only with the constant hot sun and sopping humidity, the trade winds alternate rainy seasons and hurricanes with squalls, and the extreme salinity is corrosive. It’s not appropriate to judge an inflatable boat in the tropics to more temperate regions.
Our Sultana sails during the brief New England summers, where the ultraviolet rays are not a problem. The short sailing season means PVC boats aren’t exposed as long to the elements. They’re stored for six to eight months, and even in the summer, the sun is not as damaging. The lower priced PVCs are a perfect buy in the area, as long as you avoid leaving your boat out for extended periods of time, and wipe up gasoline spills immediately.
The bottom line is your boat’s life depends on how it’s cared for and maintained. A PVC boat used daily as a dinghy to cruise ships should last about five years. The same PVC used for fishing or short family boating trips will last up to 20 years or more. We have yet to know how long the new generation of inflatable boats will last.
For further information about inflatable boats materials visit:
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