First, Merry Christmas to you and your family!
Second, thanks so much for your kindly help.

The skin's materials I had not decided before discuss with you. Now I decide use PVC? Because I can not find Hypalon liquid (if you could find, please let me know. Then I could try Hypalon and polyester), though it could make the skin more lighter and durable.
But could you please let me which folding kayak manufacturer use PVC as skin materials?

: If your seam lines are going to be above the water line you may not need to
: seal them at all. Build the boat first and try it out. If you get a lot of
: leaking from the seam holes, then let the boat dry and cover the holes.
The Hypalon which I could find only 30 inches width. Also can not be solved, because sulfuration for soft and abrasion-resist.

: Someone suggested using contact cement. If you cut a strip of your wterproof
: fabric about 30 mm wide and coat it with contact cement on one side, you
: can put a 30 mm stripe of contact cement over your seam and portions of
: both the hull and deck. When the contact cement is no longer wet, you
: press the cloth strip firmly over the area you covered with cement and the
: fabric will stick permanently and neatly. The seam will be covered. You
: can do the same on the inside of your kayak skin if you wish, but it may
: not be necessary.
I want to know if polyester can be stick with liquid hypalon.

I am in Northeast of China. Our city named QingDao or TsingTao.
Three yeara ago, when I first find there is a thing named "Folding Kayak", I know all of my life will be changed. I use all of my salary to buy two type from US, and study them, and try to develop a new type folding kayak: Cheap and Qualified and Light and easy assemble is my wish. For this wish, I give up my job, that’s really crazy.
Because qualified materials is very difficult to find in China. So my rate of progress is very low. I also visited US twice for know the market, one is Houston Boat Show, the other is Summer Market in SLC. These trips make me know the quality of products is so important.

I would try to finish the third type out March 2002. And wish this type will make me satisfied.

Sincerely yours,

Ning