I'm not sure what kind of volume is recommended for airbags. I am down to my last coat of varnish and then adding the hardware, I can't wait to get it (one ocean kayaks cape ann double) wet. Anyway, I was thinking of buying an inexpensive float tube ($50 - $60) and taking out two of the air chambers and using those. I made removable bulkheads so I can monitor them. Would that be enough volume?