Hello All,

I have some questions:

I have this tubing that has a snorkel like mouth fitting,
& it goes from the mouth, under the skirt into the volume of the Kayak.

I bought it for the purpose of practicing eskimo roll,
it's supposed to give me few more seconds of breathing the air inside the hull
so I can try & upright myself, before I wet exit.
I used it few times, but I was scared to death that the oxygen
is running out.

I know that lack of oxygen don't give any warning.
when I feel it it's too late, I'll pass out before I'll be able
to wet exit.

I also know that too much co2 does give a warning & I will be able
to exit when I feel dissyness or whatever.

so the first question is: which one of these 2 warnings works in the case
of the capsized kayak I just described ?
And also, am I correct with the knowledge about these 2 warnings ?

I have a Coho, it's 17'6" long, and about 23.75" wide,
It has 2 bulkheads, one bulkhead is 6" behind the backrest,
and the other is about 6" in front of the finger tips of my legs.

so, the question is: how long will the air in such volume would last ?
I mean when I inhale from it & exhale into it - closed system.

Any help appreciated,

Erez