Technically, you can't breathe or... inflate your lungs to it's normal capacity under water without a pressurized air supply. This is why you never see a long snorkel sold. It 's a scientific/physyological principal that's taught in Scuba diving courses. You can get a bit of air but never enough to breath normally or.. inflate your lungs to it's capacity, because they are under pressure and are actually smaller even at the 3 ft depth you're at. If you made a 2 ft snorkel and tried to use it. you would run out of air quickly and be on the surface in no time looking for air. (I've tried it!)

The guy in the "Sea Kayaker" article was able to extend his limit a bit, however he was not breathing to his normal capacity - it's impossible. If he had a hole on top (or bottom) of the inverted kayak, it wouldn't matter as far as CO2 or Oxygen content. He just can't inflate his lungs enough.

Get some free help with your roll, it's easier than you think.