So, here's a question:
Everyone says that urethane is the way to go over vinyl.
BUT, any properly designed tube uses the nylon and PVC coated nylon skin as the strength of the craft. The bladders should not be stressed within the fabric bag at all. All the bladder does is retain the air. Like the tube in a bicycle tire.
A properly sewn tube could use condom latex as long as there were no gaps in any of the seams. If you overpressure a tube, the seams in the bag will split, and only then will the bladder herniate out and blow.
Also, urethane is less than 10% lighter than PVC (1.2 vs 1.3 g/cm^3) so the weight difference is negligible. Sure the chemical resistance of urethane is better/different than PVC as is the temperature ratings, but at those temperatures you'd better not be fishing!
I guess the puncture resistance of a urethane bladder is better on paper, but if you're careful, you should never need this margin, and a Gamakatsu flying in on a hard set will go through either bladder.
SO, is it all marketing? I don't get it. How much more expensive is urethane anyway?
Can someone please explain to this engineer?
Just musing...
_SHig
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[cool] "Everyone says that urethane is the way to go over vinyl."
[#0000ff]Who is "everyone"...and how are they qualified to render that opinion?[/#0000ff]
[#0000ff]I have had tubes with butyl rubber (inner tubes), vinyl/PVC and urethane. And, you are 100% correct. The "weight rating" of a craft is more related to the volume of water displaced by the air chambers than by the strength or thickness of the air bladder walls within the outer cover. For purposes of floatation, urethane has no advantages over vinyl...or condoms.[/#0000ff]
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[#0000ff]And, I have read no reliable reports on exactly HOW MUCH BETTER urethane is than vinyl in any respect...or why it should be more expensive. I have heard more reports of seam separation on overinflated vinyl air chambers than for urethane. But, with enough abuse, any material will fail...especially when introduced to hooks, knife points or fish spines...or when seriously overinflated. There is no insurance available for "stupid tubers".[/#0000ff]
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[#0000ff]Some tube manufacturers rate their craft on the low side...purposefully...to offset the natural tendency of most people to "push the envelope". Then, there are other manufacturers who give their craft unreasonably high ratings. It is interesting to see the weight rating differences in various craft that ostensibly displace virtually the same amount of water.[/#0000ff]
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[#0000ff]From the standpoint of puncture resistance, I would have to say that I had more leaks over a shorter period of time with urethane bladders than with any of my other craft. But, the fault was not with the bladders. It was the result of the type of fishing I was doing (spiny ray fishes) and launching mostly on lakes in a desert environment...with lots of cactus spines both on living plants and lying all over the ground wherever I beached my tube or set it down for loading or unloading. Even a cast iron air bladder will not hold up well when subjected to those conditions.[/#0000ff]
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[#0000ff]I do find it amusing that the companies who provide urethane bladders in their craft seem to be the ones making all the noise about the superiority of urethane. But, when they change to PVC (Outcast) the puffery shuts down in a hurry. That leaves the door open for the other companies, still using urethane (NFO) to point fingers and use scare tactics to sell more of their stuff and to steer buyers away from the competition.[/#0000ff]
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[#0000ff]Hey, that is basic business. But, the fact remains that we all make our buying decisions for our own reasons. And, it is our OWN OPINIONS that count. It is good to listen to all of the input from all sources, but ultimately it will boil down to several important factors:[/#0000ff]
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[#0000ff]1. How much can we spend?[/#0000ff]
[#0000ff]2. How big of a craft do we need...for our size, shape and gear...and for the type of fishing we do?[/#0000ff]
[#0000ff]3. What features do we want on our craft, and who provides those standard...or reasonable upgrades.[/#0000ff]
[#0000ff]4. Are we personally satisfied with the quality of materials, workmanship and safety factors?[/#0000ff]
[#0000ff]5. What kind of transportation do we have in which to transport our craft?[/#0000ff]
[#0000ff]6. What are we willing to give up in order to get something else more important?[/#0000ff]
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[#0000ff]If we are honest with ourselves, we will usually agree that some of the "critical" factors are nothing more than being influenced by the passionate claims of manufacturers or dealers. In the absence of verifiable proof, we have to trust our own judgment and best instincts. [/#0000ff]
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[#0000ff]Whenever people ask me about safety in tubing, I remind them that driving a car is potentially the most hazardous thing in our lives, and yet we still do it. On a numbers basis, far less chance of serious injury or death in even the cheapest and shoddiest float tubes on the market. But, that is no excuse to cut corners if you don't have to. Buy the best you can afford and give it proper care. Then be sure you play safely and do not take unnecessary risks. [/#0000ff]
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[#0000ff]Good advice for all aspects of our lives.[/#0000ff]
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I can only explain it in that first off, in a float tube or a pontoon, the weight difference can be big.
Urethane doesn't decay, to my knowledge. Much like Fluorocarbon.
Urethane does stretch, but is a more durable fabric plus thicker, therefore not AS effected by temp or altitude change. By being more durable and thicker, it can hold more compressed air. meaning it can support more pay load
The outer cover does play a big part, but they are stitched and that will be the weak link.
Like a Hernia, if the outer cover does open, a PVC/Vinyl bladder will balloon, thus weakening it more. Again, Urethane being thicker, when stretching , ballooning doesn't happen. Urethane more like a freezer bag where Vinyl a balloon.
The seams on the two are going to be different with one maybe glued the other welded.
You are right about the outer cover being one the main issues. That is why NFO has gone bladderless, but the seams are now welded and not sewn.
Final note, Vinyl bladder and a really good outer cover can last for years. Urethane you just have like double armour.
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I too have used rubber inner tubes, then vinyl, then urethane.
In longevity the urethane beats all.
In strength urethane beats all.
In cost vinyl is the cheapest.
So we do the engineer's equation :
Minimum required performance vs. cost.
Vinyl wins this because vinyl gives adequate performance at a lower cost than urethane.
So does this mean vinyl is the better choice?
No. IMHO.
There is another equation to be used in the evaluation. This is where catastrophic damage can occur causing losses of great cost. eg loss of life.
So for bridges, tall buildings, life jackets, ships and aircraft there is a 2nd engineer's requirement.
That is a reasonable extra or spare unused capacity to allow for unforeseen stressful events, and avoid failure even then.
This is where I believe urethane wins. It has spare unused capacity in both strength and lifespan, for when the need arises as a result of "an unforeseen accident or need".
Is that worth an extra 50 bucks? Maybe. What price your remaining lifespan? If you buy cheapo life jackets, budget waders that you can fix when they leak, etc, probably a vinyl inner is for you. You have your float tube for less investment and more money left for gas.
If you don't like to deal with wet clothes and so buy better chest waders that last 5 years not 2, wear a top life jacket, and so on .... then a urethane inner is for you.
BTW .... a connected issue ...
I have noticed that some other people fill tubes to what I consider a "squishy" pressure ... about 2-3psi. Their tubes bend a bit on the water and sag in the middle the front and back rising up slightly. You often see it in photos.
In my urethane inner tube I have 3-4psi and the tube is hard, rigid, without "sag wrinkles" the seat is at the right angle. Very important when finning against a current or against a wear-you-out wind.
Vinyl might be near it's limit. But I am well within (unused capacity again) the pressure limit of the stronger urethane, which is closer to matching the pressure limit of the outer tube cover itself. A tube has a thin protective layer .... my attitude is it's relatively simple to have the thin layer as strong as possible.
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Very well put Norm.
I will also add, cost difference. I will bet most if not all vinyl bladders are made overseas, where most if not all urethane is made in the U.S., there inlies the cost difference.
Weight example:
Outcast Discovery 10-IR
BOAT SPECS
Inflated Size: 56" x 10' 17" diameter
Weight: 85 lbs.
Frame: 12-pc Aluminum
Air Cell Type: Vinyl
Load Capacity: 450 lbs.
Seams: Thermal Welded Warranty: 5 Year
Fabric Denier
900 PVC
1200 PVC
Made China
NFO Skykomish
Inflated Size: 62" X 10 1/2' 16" diameter
Weight: 54
Frame: 6061 Aircraft Aluminum
AIR CELL: Urethane
Load Capacity: 600 lbs
Seams: Thermal Welded Warranty: 15 year
Fabric Denier:
1,500-denier PVC tops and bottoms
Made USA
Here is the kicker......Cabela's sells both for the same price.
I understand Co. out sourcing to make a buck, but to Out Source and not lower the price for a lesser material is robbery to me.
Check out:
http://www.bucksbags.com/cm_cat.asp?id=4
One of the other USA made pontoons.
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Quote:I understand Co. out sourcing to make a buck, but to Out Source and not lower the price for a lesser material is robbery to me
Outsourceing and going to vinyl instead of Urethane and still charging the high end price could make you an Outcast.
A year after my purchasing a Fat Cat 66 (that's what they called them back in 1999) the Fish Cat came out. The price was reasonable compared to what I had paid for my tube so I contacted the fly shop that had sold me the Fat Cat hoping to pick one up for my son to use. I was told that the Fish Cat was an offshore knock off of Outcast's higher end products and that the store had no plans to carry an inferior product.
Well fast forward several years and the Fish Cat has taken off because it is a decent product. I think the company thinks that their vinyl bladdered Fish Cat's have been so well accepted that they could make some extra profit by switching to vinyl for their higher end models. (Is the Prowler still urethane?) Anyway after searching high and low for a 2007 Fat Cat I found one and just received it two days ago. So I still have my quality urethane bladder which I do think is worth having. 2 years ago my now 8 year old Fat Cat 66 had one of the seams on the bottom of the pontoon split. There was a noise like scrunching a plastic water bottle and the bladder exposed itself but did not buldge or herniate. I kept on fishing for the rest pf the afternoon and sewed it up when I got back. Last year I completely resewed the stitching on the bottom of both pontoons to avoid any further incidents with my vintage tube. I used fly line backing and my tube has been given new life. I don't need to replace it yet but I jumped on the 2007 model because I believe what Norm and Joni have said about the advantages of urethane.
God Bless,
Don
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