12V hookah?

Alright - all you project-oriented sailors out there, listen up.

I would like to know if anybody has built their own 12V-powered hookah rig for doing underwater maintenance on the boat.  I'm not talking about buying a Brownie or something, but rather using one of those ubiquitous 12V oil-less compressors... 

We're not talking about a lot of pressure here.  I am not contemplating real diving with it - I am just looking for something so that I wouldn't have to hold my breath while I scrape the prop.  At 0.5 psi per foot of depth, I'd think that 10-15 psi at the mouthpiece would be more than enough, if there was adequate flow.

So, who's already done it?