VR3

[And]

<font color='#000080'>Hi

If I recall it added about 10 mins to the 6mtr stop, that was with all the safety settings off.

We then agreed, I think, to do an extra 5 mins at 6 and then the slow ascent but it might have been 10 mins at 6 mtrs, I can't remember TBH.

I just made use of the oxygen window with my higher ppo2 at 21mtrs and slowed the ascent from there. This results in a higher average ppo2 (.95 vs .8) for deco than doing the shallow profile. Its one of those voodoo things that computers haven't been programmed with yet, but they will, eventually.

Andy

[MATTBIN]

As you guys know I dont do deco (at all) but from what I have read and only read so please feel free to rubbish my opion, I thought it was preferable to do as much deco as possible before the micro bubbles expanded and that I took to mean as deep as possible. Rarely will I agree with Andy, but from my very limited knowledge the profile he has suggested 'looks' better than doing longer stops in shallower water, is this incorrect in your opinion Mark and if so why?
Interested guys thats all dont want another punch-up, honest.

Matt

[Mark]

<font color='#000080'>

Originally Posted by [b

Quote[/b] ]If I recall it added about 10 mins to the 6mtr stop, that was with all the safety settings off.

Hi,

That's the critical point really. Your profile would have bent the computer nicely.

I would be slightly disappointed with any other outcome &nbsp;

[Mark Chase]

Originally Posted by [b

Quote[/b] (MATTBIN @ Dec. 27 2003,18:00)]As you guys know I dont do deco (at all) but from what I have read and only read so please feel free to rubbish my opion, I thought it was preferable to do as much deco as possible before the micro bubbles expanded and that I took to mean as deep as possible. Rarely will I agree with Andy, but from my very limited knowledge the profile he has suggested 'looks' better than doing longer stops in shallower water, is this incorrect in your opinion Mark and if so why?
Interested guys thats all dont want another punch-up, honest.

Matt

Not quite: The whole thing is about surface tension of the bubbles and the size of the bubbles. Deep stops i.e. stops below 3ATM will be on gassing some tissue compartments as a result a deco profile with a very low GF Low will massively extend the time you must stay in the water to exit bend free. Any benefit derived from the extended deco would be lost in dehydration lack of food, core body temp drop etc. That is why long deco (2 hours plus) will use heated suit feeds, food drops and hydration during deco. &nbsp;

The debate with Andy’s profile would be the value of the 36 and 33m stops. According to the plotted M value low these are not off gassing at all but are only on gassing, The 5% low M value being 30m below which theoretically no off gassing takes place.

The DIR debate is that extending the gas switch stop to maximise the Oxygen window at a PP02 of 1.6 for 5mins and then extending the deeper stops to take full advantage of the 50% 02 gas means that you don’t need to spend so long at 6m.

This is for the most part true but it ignores the on gassing of the nitrogen between 6 and 21m and the fact that the rate of off gassing at the 6m stop is far greater than that of the deeper stops. As a result the percentage advantage is minimal and you cant just move 1min from the 6m stop and add it on to the deeper stops and have the off gassing rate stay the same.

Whether this works or not is beyond my level of knowledge but it doesn’t conform to accepted theories of decompression. Deep stops are a good way of minimising the damage to the body caused by bubble expansion using the old style fast ascent rates like 18m/min. It was accepted that deep stops added to the total deco. The new DIR theory of smoothing the deco curve is not a proven science and it is taking the whole deep stop theory one stage further. GI3 if you read his stuff will tell you he was shaving hours off of accepted deco profiles. Mark Ellison has apparently knocked 4 hours of the accepted deco for the dive he did. Great but I am too old and unfit to be a ginypig. I have seen divers do apparently safe profiles with the so-called conservative and oh so slow computers and then get badly bent. I have also seen divers have rapid ascents miss stops and have no side effects or apparent DCI. Go figure.


If the dir profiles work for the individual then that’s great but I don’t think starting out aggressive and working backwards is a good idea. I would start out really conservative and move to a more aggressive profile if I was feeling good, conditions were good and the time saved for deco was significant enough to waren’t the risk, which in OW diving in most cases it isn’t.

Personally I will add or pad as many deep stops as a diver wants but I won’t shave off the 6m stop in order to achieve it I will just add them to the total deco.

I have read about divers getting bent on the VR3 set to 0 safety. Bearing in mind than on a 50m dive the VR3 will get me out of the water about 11 mines quicker than my Vytec. Then someone wants to shave another 10mins of the VR3. I am sure some people can get away with it but I will not accept that it’s a safe profile. Cutting edge, adventurous, aggressive yes but not safe and definitely not for old fat gits like me.

ATB

Mark Chase

[Mark Chase]

Originally Posted by [b

Quote[/b] (Mark @ Dec. 27 2003,18:03)]

Hi,

That's the critical point really. Your profile would have bent the computer nicely.

I would be slightly disappointed with any other outcome  

No, it worked out at 10mins longer for deco in total not with the extended deep stops that Andy proposed. The only way to find that out would be to run Andys dive a a simulation and force the computer to mimic his stops. I didn do that but Ile have a crack when I get back form Egypt. My VR3 is packed at the moment.

ATB

Mark Chase



ATB

Mark Chase

[SINEX]

<font color='#FF7F00'>Just to answer you original question ! &nbsp;The VR3 C1 for Open Circuit Air &amp; Nitrox is available for only €825.00
Should you want to add on an O2 Analyser it costs another €403.00 but this price includes the full kit for the unit, including the PIN number for the VR3 to unlock the software, the linking cable, the O2 cell and the Analyser connection unit. If you are still interested take a look at Bang On's site. www.divertec.net