cochran - blend switching??

[Les]

I have had my cochran commander nitrox computer for about a year with the intention of using it for dual mixes of gas at a later date.That date has come.I have bought an alternate air source for redundancy,and to extend my bottom times when I choose to.I dive with nitrox(usually 32% for my primary cylinder and up to 40%max for my pony.Now reading
my owners manual is quite confusing. I know how to set up the different mixes but it is not air integrated so how does the computer know when you have gone off your primary and onto a different mix.Do you just program into the computer that you will be on one mix at a certain depth for X amount of time and after that X time it automatically switches over to my pony mix? Not sure.My local dive stores don't sell cochran.The store I purchased from is not in business unfortunately.Sold business to move to US and make a real paycheck.Anybody out there with an answer would be appreciated.For now just diving both cylinders at my lowest nitrox percent.

 

[ericfine50]

When you program the mix, you also program the depth. So at XX depth it will switch for you.

In your post you said you have 40% in a pony. Is that for decompression? If so, rig it as a stage, if not don't put a higher % mix in a bottle. Bad idea, can getta hurt.

The Cochran has a bad rep in the US for failing. You may want to look into selling it and getting a Nitec 3 by Dive Rite, it is a 3 gas computer and allows the user to switch the gases.

Have you had any training for the "deeper" stuff? If not, try to hook up with a good instructor that teaches a sound,well rounded class. Check out GUE at http://www.gue.com for some of the best training I have seen to date.

Eric

 

[Mario S Caner]

Les, I'm afraid I'm going to have to agree with Eric's post in that Cochran has a very bad rep here. In fact there was one individual whom defended the brand here on the boards, but his failed on him during a recent trip. If you are interested in the specifics, you can contact Iguana Don through the boards.

Some other good computer choices would be the Abysmal Explorer, DiveRite Nitek 3, and the OMS VR3.

Good luck, and please keep us posted.

 

[Atomox]

It sounds like you are trying to do some decompression diving. If not, then there is little benefit to having a hot mix in your pony, and 40% is not a good deco gas. In fact a hot mix increases your chances of having a serious accident. If you are doing deco dives then you should have a fully redundant system (this includes a buddy) with tables for backup. Also, having backup tables with a Cochran is mandatory (my opinion). There is a tremendous amount of planning that goes into deco diving, it is not something that should be done without the knowledge of the consequences that can happen if done incorrectly.

 

[Les]

Thanks for your input everyone. My main reason for the pony is for redundancy for an out of air situation for myself or another diver in need. Not that I plan to be anywhere near out of air. I am very particular with checking my air. If I choose to extend my bottom time and still be within NDL's I can ascend on my pony and reap the benefits of the higher o2%. Maybe my spg for primary cyl. will fail and I will have to abort the dive and ascend on the 30cu'with its own spg?? I don't dive to the max operating depth so my oxygen toxicity level will be ok. I have never used up my OMS 112 to minimum 500 psi on a single dive before. That's alot of juice, but I do appreciate the concern. And I do dive with a bottom timer as a backup and with my trusty tables by my side. Anyways keep in touch.

 

[ericfine50]

Les,

But, in you orginal post you talked about extending your BT. The pony is not used for that. Sounds like a two gas computer is not going to help you for that. If you put a hot mix in that 30 cu. ft. bottle and a buddy or another diver does run out of air and you are near or below the MOD for that mix, you are going to have problems.

Sounds like you may want to look at a set of doubles or carry a single stage with your single tank.

Eric

 

[Les]

thanks ericfine50 we are on the same track,just worded differently.I understand where you are coming from with the hot mix.right now don't dive to those depths(mod).so I am basically running a single cylinder with a single stage.
Les