ClayJar:Actually, nope. It's not exactly pleasant (hehe, it's nothing to sneeze at), but it's not really that big a deal.
The mitigating factor is that often when you throw up underwater, it seems to usually be seasickness, which likely started on the surface, thereby pre-clearing most of the chunkiness. If you *do* chunk your reg, you just grab your alternate while you clear out your primary. Note that this will also reinforce your buddy's vigilance regarding air management. They *won't* want to have to share air with you.
Process for hurling under water (while adhering to rule #6)
Stop and get proper buoyancy and trim.
Signal buddy to watch you
Prepare to hurl
Take good breath and take primary out of mouth
Turn head to left or right
Let it go and force with breathing out
Put regulator back in mouth and purge
Signal okay
It is important to turn head to left or right so that a: you dont get the stream in your face and B: you look in complete control. This made one of my buddies laugh so much, he spit out his reg.
I sometimes eat the worst stuff before diving and my stomach disagrees with it, so this is now down to a science....
