Main Tube Inflation Question

dspid2404 · Post by **dspid2404** » Mon Sep 20, 2010 11:52 am

I have had my Expedition for approximately 2 years now. The question I have is if one of the main tubes loses all of its air how much can the remaining tube be inflated to take up the lost space. In other words, if you lose the main tube #2, which was approximately 50% of the air in the main tube when properly inflated during setup, can you pump tube #1 to fill 60 or 70 or 100% of the main tube. Also would doing so cause any damage. I hope that is clear.

Post by **JCOOLEY** » Mon Sep 20, 2010 12:40 pm

If you put most or all of the air into one chamber instead of dividing it between the two then what can happen is the membrane that seperates the two chambers can tear away leaving you with on a one chamber tube. If you are thinking of this because you have a hole in one chamber then you risk seperating the membrane and if that were to happen, then all of the air would escape from the hole if there was one.

Jeremy

dspid2404 · Post by **dspid2404** » Mon Sep 20, 2010 3:22 pm

Jeremy - What I'm thinking is in a case of emergency. I guess the best way to ask is at what point would the membrane begin to fail? I'm only asking this because I want to know the limits of the kayak. You never know when you may need this type of information. I'm not asking what it is designed for but a ballpark guess, unless you know.

Say you hit piece of coral and you tear as far as one of the tubes. You repair the hull and you still have a LONG way to go. You would want to fill the remaining tube with at least some additional air so you're not riding on a floating bean bag (sorry all I could think of). How much can you fill it before a problem would occur?

Post by **JCOOLEY** » Mon Sep 20, 2010 3:37 pm

I understand. Probably about 75% so you don't damage the membrane. If you wanted, you could risk putting closer to 100% but I would fear that the membrane would give and then your kayak would go flat. If you are using a pump with a gauge, around 1.5-2 psi max.

dspid2404 · Post by **dspid2404** » Tue Sep 21, 2010 2:56 am

Good to know. Hopefully none of us will be in that situation but it is a good information to have. I wouldn't want to "have a long way to go" with one tube over open water but thing happen.

PJohanson · Post by **PJohanson** » Tue Sep 21, 2010 10:11 am

It's worth noting that the kayak will float just fine with one of the two main chambers. With one pierced and the other inflated to 75% as suggested, it should be fine for paddling. It won't be as rigid and efficient as if it were properly filled, but it will be managable.

dspid2404 · Post by **dspid2404** » Tue Sep 21, 2010 12:32 pm

Better than 50% anyway.

Snook · Post by **Snook** » Tue Mar 08, 2011 7:57 pm

I am relatively new in kayaking and I am learning so much from this forum, But I do not understand the "anatomy" of the main tube with two chambers.

I am wandering if some of you have a draw of them, or where can I see a picture.

thanks a lot.

dspid2404 · Post by **dspid2404** » Tue Mar 08, 2011 9:10 pm

I don't know if I have seen a picture of them. Basically you have two plastic tubes that go all the way around, more or less, inside the canvas tube of the kayak. Each one is designed to inflate 50% in normal use. This is why you inflate each one with approximately the same number of pumps. What we have been discussing above is in an extreme emergency case.

Post by **Pearly** » Tue Mar 08, 2011 9:18 pm

OK - the image on the left is a top view of the tubes if you take them out of their cover. The Dark grey is the outer tube, the light grey is the inner tube.

The image on the right is a section through the tubes - as if you cut through the tubes with a knife. Two chambers separated by a membrane - one valve for each chamber.