Pete,

What can I say? You can continue to call bullshit, chocolate pudding, but 
it is still bullshit and tastes horrible. We're not talking about fully 
tested technology in the hands of rigorously trained professionals. This is 
technology that even in the envelope for which it was developed is still
considered advanced and for advanced users only.

Those guys screwed the pooch because they fucked up. Plain and simple. It's 
a shame, because I here they were nice guys but don't blame that accident 
on open circuit technology. The second they decided to penetrate an 
unfamiliar wreck, they extended their target risk.

Rebreathers (as they exist today) are neither sufficiently fault tolerant 
nor user friendly enough for them to be considered an added safety 
advantage. If you tell me you want one because they are cool or a challenge 
to dive or even because it will help you get laid, fine, those reasons I 
can accept. I will not accept that today's rebreathers are a safer means 
for sport divers to accomplish their goals. There are cases where 
logistically speaking, a rebreather may make a dive or a series of dives 
more feasible, but at a loss of reliability and safety. Ask Kevin how much 
of the Monitor he saw this summer. - Tony


______________________________ Reply Separator _________________________________
Subject: Gas margin, safety with rebreathers
Author:  heseltin@hs*.us*.ed* at EXTERNAL
Date:    10/4/96 1:20 PM


Tony,

My point was not that fools would be saved by using a rebreather. As soon 
as you build something that's fool proof, they build a smarter fool. 
However, rebreathers can provide an extra margin of gas to divers who are 
already close to the limits, by choice and planning, than with current OC 
equipment.

Consider the case of two very experienced divers who go to explore a new 
wreck. They carry with them stage bottles, which they leave outside the 
wreck. During the wreck penetration, one diver gets hung up on wires and 
it takes some time to disentangle him. They realize that their actual 
bottom time is now considerably greater than planned and they exit the 
wreck, but because of currents, poor viz, they are unable to relocate 
their stage bottles. They head for the surface, without completing their 
deco obligation, but both arrive in bad shape and though transported to a 
chamber, both eventually die. This actual case, which some may recognize, 
*might* have ended differently if they had, on their backs, sufficient gas 
to meet their deco obligation. Most disasters are multi-factorial. A 
variety of points can be altered in the above scenario to acheive a better 
outcome. Having enough gas with you at all times is just one of them.

It is nihilistic to regard advances in technology, because they are 
inherently more complex, as increasing risk. You drive to work and fly in 
airplanes that are phenomenally more complex than even a few years ago. 
Most would agree that this increase in technology/complexity has increased 
the safety of travel. True, some increase in technology merely offer the 
opprtunity to do it faster or more carelessly. This has been the subject 
of several debates on ths list. I refer you to the book Target Risk by 
Gerald Wilde. You can access it at http://pavlov.psyc.queensu.ca/target/

Despite this, there will be those who use the new technology to increase 
their safety. Look at how dive computers have become quite standard among 
sport divers over the past ten years. Sure, people use them because they 
perceive an advantage - increased bottom time. And, there are those who 
say that computers do not increase safety over tables. But, Joe Average 
Diver is less likely to make a mistake reading his computer than 
calculating tables, particularly on the fly. More to the point, this major 
increase in technology has not resulted in a noteable increase in injuries 
or deaths. Other will use the new technology as a means to push the 
envelope or do stupid things. They will die or get injured. It's a matter 
of adult choice.

I do not believe that rebreathers will replace OC soon, anymore than I 
believe that off-road vehicles will replace walking or mountain bikes. But 
people will use rebreathers, for the most part for different purposes than 
OC. I still stand by the idea that some tech divers will find it useful, 
easier and safer to carry their gas supply with them and have a greater 
margin than is practical with OC.

-peter heseltine

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