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 Post subject: TPU hulls
PostPosted: Mon Nov 20, 2017 4:46 am 
forum fan

Joined: Mon Oct 16, 2017 2:31 pm
Posts: 17
Hello all
I think it would be interesting to find out from any owners of TPU hulled kayaks what their opinion is on the robustness of this material. I have been looking for info but here doesnt seem to be much on the long term durability,abbrasion resistance etc of TPU.
So if anyone has any longterm experience of TPU your opinions would be appreciated.
Jules


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 Post subject: Re: TPU hulls
PostPosted: Mon Nov 20, 2017 4:41 pm 
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Joined: Mon Apr 13, 2015 2:10 pm
Posts: 72
There is no simple answer to this question. To illustrate, here is a quote from Wikipedia: "Thermoplastic polyurethane (TPU) is any of a class of polyurethane plastics with many properties." Basically, any polyurethane that you find in a fabric is a TPU. A good TPU material has very good abrasion resistance. It does not stand up to UV degradation as well as PVC, but this problem is effectively solved by using black pigment that does not let UV light penetrate.

As a hull material, TPU is one of several factors to consider. It does not by itself have much tear strength, and it is too elastic for most folding boat applications. This issue is addressed by adding a substrate layer - usually woven polyester. The quality of the final TPU hull material is determined by the TPU itself, the thickness of the abrasion layer, the adhesion to the substrate, and the quality of the substrate. In addition, an inside TPU layer may be needed to provide some abrasion resistance inside the hull and provide a surface that another TPU fabric can be RF welded to.


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 Post subject: Re: TPU hulls
PostPosted: Thu Nov 23, 2017 3:22 am 
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Joined: Mon Oct 16, 2017 2:31 pm
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Hi Alv
I wonder if it would be more useful to ask users how long they have had their TPU hulled boats and has it held up well for that time considering the way they use it.
I have tried to find long-term use reports for TPU hulls but they seem to be few and far between. It is commonly reported that Hypalon last 20-30-40 years TPU has been around for a fair bit of time now so there must be people who have some of the first boats who could give us an idea of how it holding up.


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 Post subject: Re: TPU hulls
PostPosted: Thu Nov 23, 2017 10:57 am 
faltbootemeister

Joined: Tue Feb 05, 2013 1:15 pm
Posts: 121
Hi watchkeeper,

It's good to have Alv's insight on the materials used in folding kayaks. I was hesitant to answer your question until Alv's post. I have owned a Feathercraft Big Kahuna for seventeen years. As far as I know Feathercraft has never referred to it's hull material as TPU, but it is a polyurethane material. The Kahuna is in very good shape with little to no sign of wear to the skin. The material is still supple and all the welds are fine. While I have been careful not to drag the kayak across rocks, glass, concrete etc. I have not babied it and it has held up well.


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 Post subject: Re: TPU hulls
PostPosted: Fri Nov 24, 2017 4:46 am 
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Joined: Mon Oct 16, 2017 2:31 pm
Posts: 17
Hi Jeremiah
I'm am looking at a TPU hull and having only used hypalon in the past I'm interested to know what people think about it after actually using it.
Alv certainly seem to know a lot about TPU ,more than my ''its black and kind of rubbery'' level of knowledge.
OK so you certainly have a positive experience with your ''TPU'' hulled Feathercraft and thanks for the input lets hope we get more people contributing.


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 Post subject: Re: TPU hulls
PostPosted: Fri Nov 24, 2017 1:32 pm 
faltbootemeister

Joined: Tue Feb 05, 2013 1:15 pm
Posts: 121
Hi watchkeeper,

I have had experiance with both hypalon and urethane hulls from Feathercraft. Before my Kahuna I owned a K-Light that I purchased in '95 that was made with hypalon. That hull has held up very well also and is currently owned by my sister-in-law. If I had to compare the two materials I would say they are both long lasting and robust with the hypalon being a touch more supple (but that could be from the substrate material).

I have not seen "TPU" used before or after Folbot's use of TPU in their original Cooper kayak. This was quickly changed to hypalon after some customers complained about it's durability (to be fair, some customers said the TPU hull was perfectly fine for them). After Alv posted I asumed you meant any polyurethane materials now being used in many folding kayaks (as well as differant inflatable crafts).


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 Post subject: Re: TPU hulls
PostPosted: Sat Nov 25, 2017 2:44 am 
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Joined: Mon Oct 16, 2017 2:31 pm
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Hi Jeremiah
Being a complete fabric novice and getting all of the info I have from the various manufacturers my ''TPU'' reference translates to not Hypalon ,not PVC but the other urethane fabrics on offer for folding kayak hulls . Klepper advertise as using TPU now Wayland also offer TPU so it this third hull material that I'm interested in I spoke to one hull maker who rates it above Hypalon and told me that 80% of their hulls are now delivered in TPU so I guess it must be pretty good but there is still little on the internet about long term usage.


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 Post subject: Re: TPU hulls
PostPosted: Sat Nov 25, 2017 6:57 am 
Brotherhood of the Golden Paddle

Joined: Mon Apr 18, 2005 3:40 pm
Posts: 1105
Location: isles of scilly UK
As Folbot has been mentioned we must look at the new hull material they started to use. It was called ELVALOY and proved, in my opinion from what I saw on the forum, (folbot section page 3). It appeared to very difficult to patch and keel strips if anyone wanted them almost impossible to attach even at the Folbot factory. So check if TPU is easy to patch in the field.


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 Post subject: Re: TPU hulls
PostPosted: Sat Nov 25, 2017 7:47 am 
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Joined: Mon Oct 16, 2017 2:31 pm
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Hi John
Good point I hope that someone will be able to give us some examples either way if TPU is easy to repair or not.
I will take a gander at the folbot section and see what that's all about.


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 Post subject: Re: TPU hulls
PostPosted: Sun Nov 26, 2017 6:21 pm 
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Joined: Mon Apr 13, 2015 2:10 pm
Posts: 72
We (Pakboats) had concerns about using TPU, partly due to the fact that we did not feel that the available adhesives were suitable for field repairs. That includes Aquaseal, which has been available for decades. You can get a decent bond with Aquaseal, but the cure time is too long to be convenient in the field. The Clifton urethane adhesive works very well, and we use it in our TPU repair kits. The Clifton adhesive works well on PVC too, but there are good PVC adhesives for half the cost. The main problem with Clifton adhesive is that it is not widely distributed outside North America.

I am not surprised that early experience with TPU hull materials has been mixed. We all have to start somewhere, and that means that we need to deal with a learning curve. We were not happy with our first TPU material. The second was much better, but not as good as what we use now. You may wonder if another improvement is in the works. I am happy with our current material and am not looking for better alternatives, but I'd be happy to adopt an improvement if I find something better at reasonable cost.


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