On Thu, 27 Jun 1996, rfarb wrote:

> Carlos, open circuit scuba will never be a thing of the past in any 
> length of time short of geologic time. Rebreathers require more time to 
> deal with than open circuit. There are disposables besides gas that cost 
> money to replace regularly. You have to think more when you dive the unit 
> and check more gauges more often during the dive. You can't just whip the 
> mouthpiece out of your mouth like open circuit and make gas rings- you 
> have to close the mouthpiece valve so no water gets in when the 
> mouthpiece is out of mouth.

Rod's right on the money.  Now, everytime I blow gas rings on the deco 
line, I have to first shut the mouthpiece. BUT, the good news is that 
with a rebreather, you can watch the rings go all the way to the 
surface.  As any experienced scuba gas-ring-blower knows, as soon as you 
exhale your next breath after you blow some rings, the exhaled bubbles 
ascend faster than the rings do - so they catch up to the rings and 
destroy them.  But with the breather, there are no bubbles from your next 
exhaled breath, so you can watch the rings go all the way up.  The 
technique works so well, in fact, that we have abandoned all of our comm 
gear and uplines, and now spell-out messages to surface support through
creative air-ring blowing.

> For a fully closed circuit unit, you have to 
> know diving physiology without thinking about it to much. You must be 
> able to logic out what the unit's gauges are really telling you. For 
> trimix you gotta cut tables to dive it or get Marco's computer for the 
> unit at $3K.

Or buy a rebreather with an integrated decompression computer.  Better 
yet, buy one with tripply-redundant integrated decompression computers.

 If you cut tables you got to have a portable computer to 
> take on the boat. You got to have O2 and other gas for the unit no matter 
> where you are. You really ought to have a Haskel pump to pump and a good 
> digital pressure gauge to mix. You got to have big buckets of scrubber 
> whereever you go. Extra O2 sensors. You got to have HP hoses with cga540 and 
> 580 fittings. If you get the 6K psi He you got to have the CGA667 fitting 
> for it. You got to have an O2 analyzer. Got got to have a laminator to 
> laminate all your dive tables and a portable printer to print them out or 
> you could write them all on a large slate. All of this besides the usual 
> dive gear.

You also need at least one screwdriver, two wrneches, and buckets of 
Cristolube.

> Open circuit will never go away in the face of this. BUT what 
> the rebreather does is free you from thinking too hard about running out 
> of gas which you won't do long after the open circuit guys are up and out 
> of the water and back at the dock. Rod 

All kidding aside, I completely agree with everything Rod said.

Aloha,
Rich

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