The Strongan Duotex Difference

As I walked around the shop “topping off” all the CSM/Hypalon boats this morning I thought to myself, “How come no one talks about air retention on Strongan vs Hypalon?”. This is a very valid question to the person looking for a tender or stand alone inflatable boat.

Let me put this into other words, Strongan is what we casually refer to as PVC here at the shop when discussing boat materials and manufacturing processes. To be so casual is actually kind of detrimental to a degree. When discussing PVC inflatable boats many makers will spec out their fabric in mils (equal to a thousandth of an inch) or millimeters also expressed as “mils” on various websites albeit incorrectly in efforts to dupe the customer. The other manufacturers count on you being uninformed to swell their bottom line. Further use of incorrect terms along with drawings and lots of text that “sounds official” on their many websites plus dubious reviews means you end up with a cheap boat that came with free shipping and absolutely no support. Any boat deal that comes with free shipping should be a red flag just so you know.

Cutting down on the volume of calls we receive here at IBC from Amazon or Ebay bargain shoppers means it’s time well spent to bother with this topic.

Obviously we don’t sell brand X nor do we offer free shipping. I can’t understand why other brand/site customers call us all day long for support of someone else’s product. Weird huh? The simple answer is those sites like Amazon or Ebay don’t have a support structure, they offer cheap products with free shipping to capture the bargain shopper. They don’t have a store, or a phone, or employees to take the millions of calls about their junky products and their failures.

Going back to formula we’ll first educate you about what Strongan is and what PVC and Hypalon isn’t. Using our time machine let’s go back to the polyester years of the 1970’s! 😉

Strongan Duotex is a fabric originally developed by the Espace Division of Zodiac France as part of a joint project with CNES (National Space Research Center). Developed to be better at air retention and water intrusion than ordinary PVC it was further refined and developed to be Thermobonded by purpose built machines existing only in Zodiac France.

Basically PVC was a truck cover material that was semi-water tight but not airtight, (more on this later). The Zodiac answer from the joint space research project took 8 engineers and technicians and a support staff of 14 to tackle.

“Welding” of PVC used in the knockoff industry is a lap seam. One layer is placed on top of another and heated under pressure to make the bond. This technique will make most PVC materials watertight but leaves something to be desired for airtightness.

To accomplish this technical feat Zodiac developed their thermobonding process where two precision cut pieces are butted up edge to edge and overlayed on the outside for mechanical strength, and the secret internal layer overlayed on the inside defeated air leaks and made the bond airtight.

Zodiac Strongan Duotex outside seam
Zodiac Strongan Duotex inside seam

While seeming relatively simple to the layman, the material science and process engineering was very difficult and very costly. Zodiac invested heavily in the engineering of the process and at the time it was considered a gamble. The old guard of neoprene sand and glue construction people never thought PVC could have the air retention of Hypalon/Neoprene. Zodiac’s gamble paid off, and dramatically lowered the costly labor process involved by 75% while producing a boat unparalleled in air retention and strength. This hyper-technical approach catapulted Zodiac’s aerospace and leisure products divisions to the forefront of their respective industries. Yes from the humble beginnings of Maurice Mallet’s sewn and varnished balloons in 1896 to 21st century space exploration and Strongan Duotex inflatable boats Zodiac reigns supreme.

To sum it up in a few words Zodiac’s Strongan Duotex fabric is the gold standard for air retention and modern inflatable boats.

Saying that all boats are not cut from the same cloth is a gross understatement. Buyers should beware the great pretenders in the market today all vying for your hard earned dollar.

Today when I went to IBC’s repair shop to measure the differences in thickness from one brand to the next I was amazed at the startling differences between the Zodiac Strongan Duotex and the ordinary PVC from the other manufacturers. The average measurement in mils or thousandths of an inch of the most basic Strongan fabric was .040″ and the next best competitors came in at .015 to .029″ or one to two thirds thinner. The average thickness of a Thermobonded seam was on the order of 1/8″ or .125″ compared to a seam of .030″ to .060 for the others .The Zodiac fabric is thicker by it’s self than many other manufacturers seams! So thickness of the Zodiac Strongan coupled with the additional thread in the scrim or substrate of the Zodiac Strongan fabric adds additional strength and resistance to forces such as torsional loading over all other manufacturer’s samples compared.

Much has been written about the dreaded UV rays and the havoc it wreaks on boats. Myths abound on the internet of UV radiation turning boats brown and causing them to “pop” while exposed to the sun. I would refer you to the earlier paragraphs to note that Zodiac’s Strongan was developed with the space program in mind. Believe me there is far more UV in space than at the waterline.

UV damage mechanisms of the various materials here on Earth generally cause what’s known as “photo-bleaching”, whereas the material in question turns white not brown. The mechanism is virtually the same for PVC, Hypalon, and even diamonds! Look at an old car dash, did it turn brown, or is it whiter and bleached looking? I thought so! Short wavelength high frequency radiation in the UV regime and it’s interaction with matter is well understood. One simply can’t take a random website’s claims as truth these days, we’ve even added “fake news” into our language to define this phenomena.

Generally speaking all inflatable boats are called Zodiacs today due to commonality in conversation, but all inflatable boats are not cut from the same cloth. If it doesn’t say Zodiac on the boat it’s not a genuine Zodiac, ask for it by name.

Note: Bombard and Avon are both Zodiac products.

Edit: Richard Meister (Technical Support Manager at Zodiac Nautic) added to our Facebook page “Environmental positives too! Strongan plastomer is thermoform and can be melted and recycled. No wasteful and annoying dust generation either.

What Richard means by dust generation is Hypalon/Neoprene fabric requires sanding and scuffing prior to cleaning with toluene solvent, then finally several applications of adhesive are added to make a seam or install a simple patch. This dust, solvent, and adhesive is a potential hazard if improperly controlled during the assembly and repair process. While Zodiac leads the world in green environmentally sound practices, those other boat builders, errr…. not so much.

To see what Richard means about recycling of materials one only needs to look as far as the Bombard Air Ethic. The Bombard Air Ethic is made utilizing green manufacturing processes, novel materials and recycled materials. This represents a first in the boat building industry.

Thanks for bringing up those valid points Richard!

Hypalon/Neoprene or as it is generically called CSM is a man-made artificial rubber coating over a substrate or scrim. It offers some advantages over plain PVC with the foremost being resistance to solvents and fuels. UV absorption is virtually identical to PVC and several other materials such as Urethane and with all of the hype and misinformation this is a hot button topic for the web forums and novice yachtsman. If you had any doubt just look at the multitude of aftermarket products that claim UV resistance and protection catering to the hyperbole.

Hypalon performs slightly better in the drum test for abrasion resistance than PVC but in terms of air retention it fails miserably compared to Zodiac’s Strongan Duotex. Hypalon inflatable boat manufacturing is a very dirty and labor intensive process taking up to three times as long to complete when compared to a Zodiac Strongan Duotex inflatable boat of the same dimensions. This labor comes at a cost and this added cost is much of what the customer assumes is quality when simply comparing prices. Remember the statement that not all boats are cut from the same cloth? This holds true for Hypalon boats as well. That “good deal” for a brand X  Hypalon boat will cost you in the long run on repairs. You are much better off sticking to the brand that started it all…Zodiac, Avon or Bombard when asking about Hypalon inflatable boats.

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