Recommended options on new rebreather (Optima CM)

[LFMarm]

Define "secondary computer"
NERD attached to the loop is right in front of you. Really nice.
Bail out, off the loop, a computer on your wrist is so much easier to keep tabs on. NERD is hanging out on the loop, not in front of your face. You have to actively retrieve it, pull it to your face and look at it. You have to dedicate a hand to hold the NERD in front of you (when off the loop) where a wrist just takes a moment to glance over at it. If you have both hands busy, you can still look at a wrist, you are not looking at a NERD. So while a NERD is great while on the loop, it is still functional while off the loop, actually seeing the function can be difficult without a spare hand
The last stage of transitioning to bailout is to switch the NERD over from CCR to BO mode. And that is if the other task loading isn't too high.

What I mean is that when bailing out you forget about the loop and start using your secondary computer (for me a Perdix)

 

[broncobowsher]

What I mean is that when bailing out you forget about the loop and start using your secondary computer (for me a Perdix)

Six of one, half dozen of the other. Flip which one is the controller and the monitor, don't see it making a difference. I'll go with the petrel being the controller as it has a better history, NERDs have a historically higher failure rate.

 

[DiveTucson]

This thread is starting to crack me up. People on here that don’t have time on the CM which is what this thread was started about. We are now discussing computer options that are not even standard. The CM is not offered with a Petrel controller and NERD monitor or the other way around with a NERD controller and Petrel monitor. In fact I have not seen a unit setup this way at all. The factory configuration is a NERD or Petrel controller with the Shearwater HUD. What works well on a rEvo or some other unit may not work the best on the CM unit.

I have worked with several dozen students (40+ now) on this unit and I can say hands down the NERD controller is the way to go in my opinion and is the most common configuration. This makes the unit fully self contained. The only thing that attaches the unit to the diver is the four bolt snaps.

If you have to BO switch the NERD to BO mode and switch your stand alone computer to BO mode as well. Follow the deco schedule on the stand alone and confirm with the NERD data if needed. There are benefits to having a standalone computer that is not attached to the unit at all.

 

[mdwalter]

This makes the unit fully self contained. The only thing that attaches the unit to the diver is the four bolt snaps.

... and the dil hose, (and the DSV in your mouth of course), and maybe the scooter ring extension if you decided to obtain and use that (I have not), and maybe the O2 hose if you decided to not mount that to the bottom of the RM (but to butt mount or stage mount it instead). That said, even all of these (5 total clips, 2 QDs, closing DSV) together is probably less work to get disconnected than taking the Petrel off your wrist and securing it to the rest of the unit so it's not flopping around, so you're still right that it greatly simplifies removal of the unit from your body.

 

[Mastow1]

The Shearwater Petrel 3 Fischer Computer-controller (now available from Dive Rite) combined with a HUD is the best Optima-CM configuration for me because it:

1. Is the safest configuration. Most of the CCR fatalities I have reviewed were caused by breathing toxic PPO2. Tunnel vision (intense focus on a visual stimuli that results in screening out of peripheral sights and sounds), hyperfocus, (complete absorption in a task, to a point where a person appears to completely ignore or tune out everything else), narcosis, stress, or even fatigue, may lessen the effect of flashing red numbers and audio warnings indicating problems. The Petrel 3 adds, all but impossible to ignore, strong vibration warning alerts to its usual red flashing warnings. The HUD remains a redundant visual alert/information system.

2. Allows for the display of four gas pressures on the controller and allows for easier programming than the NERD and makes system information readily available and changeable, to other divers. I have not dived a NERD, but I enjoyed having the HUD’s light signals in my peripheral vision. For me providing the information in a different format than the controller, keeps me aware and vigilant. Or perhaps I’m just too cheap to buy a NERD.

May all your dives have the surfaces you planned.

 

[grantctobin]

The Shearwater Petrel 3 Fischer Computer-controller (now available from Dive Rite) combined with a HUD is the best Optima-CM configuration for me because

I acknowledge it might be a typo, but in case anyone else reads this: if it is Fischer, it is not a controller.

 

[Mastow1]

Not a typo, but my ignorance. I meant the Perdix 3 that comes with the rebreather.
I thought it was the Fischer. Thanks for the correction and education.

 

[tbone1004]

The Shearwater Petrel 3 Fischer Computer-controller (now available from Dive Rite) combined with a HUD is the best Optima-CM configuration for me because it:

1. Is the safest configuration. Most of the CCR fatalities I have reviewed were caused by breathing toxic PPO2. Tunnel vision (intense focus on a visual stimuli that results in screening out of peripheral sights and sounds), hyperfocus, (complete absorption in a task, to a point where a person appears to completely ignore or tune out everything else), narcosis, stress, or even fatigue, may lessen the effect of flashing red numbers and audio warnings indicating problems. The Petrel 3 adds, all but impossible to ignore, strong vibration warning alerts to its usual red flashing warnings. The HUD remains a redundant visual alert/information system.

2. Allows for the display of four gas pressures on the controller and allows for easier programming than the NERD and makes system information readily available and changeable, to other divers. I have not dived a NERD, but I enjoyed having the HUD’s light signals in my peripheral vision. For me providing the information in a different format than the controller, keeps me aware and vigilant. Or perhaps I’m just too cheap to buy a NERD.

May all your dives have the surfaces you planned.

I can all but guarantee that you do not have a Petrel 3 Fischer controller.... The cable that comes on them is a Subconn connector which is infinitely superior to a Fischer cable. Those should have gone the way of the dodo 10 years ago but for some reason still linger on like damned cockroaches.

 

[lostsheep]

... and the dil hose, (and the DSV in your mouth of course), and maybe the scooter ring extension if you decided to obtain and use that (I have not), and maybe the O2 hose if you decided to not mount that to the bottom of the RM (but to butt mount or stage mount it instead). That said, even all of these (5 total clips, 2 QDs, closing DSV) together is probably less work to get disconnected than taking the Petrel off your wrist and securing it to the rest of the unit so it's not flopping around, so you're still right that it greatly simplifies removal of the unit from your body.

I regret not getting the NERD from the get go for the self contained aspect. That said, it's really a non issue to take a perdix off your wrist and to stuff it in the front pocket or clip to the loop.

One advantage the Perdix has over the NERD is user changeable batteries; I hate integrated batteries with a passion. YMMV

 

[lostsheep]

As @DiveTucson

If you need the HUD, then grab the head, pull on it, and clip it onto the left side of your NERD's bracket.

I hadn't even thought about where the HUD would go if the NERD failed; anyone got a picture of this?