Curt, Thank you for the greetings. I am a novelist doing research on a freshwater salvage at about 230 feet using rebreather apparatus. In my youth I did have a NAUI certification and dove in the cold, cold waters of Puget Sound, WA, USA (in a wet suit) for about a decade, but I have not dove in decades. My interests are in learning a bit about rebreathing gear, terminology, and developing a reasonable decompression regimen for dives of 15-20 minutes at depths just over 200 feet. The scenes need a bit of authenticity and no fatal errors. Thanks, D