Recommended options on new rebreather (Optima CM)

[stretchthepenn]

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

Here are two photos. The unit is laid out on my garage floor.

The left photo shows the unit in normal dive mode; the NERD displays into the diver's right eye, and the HUD pokes up between the rebreather and the diver's body.

The right photo shows the unit with a NERD failure; the HUD is deployed and clipped into the NERD's mount.

 

[lostsheep]

I didn't realize there was already a clip for the HUD, I (wrongly) interpreted your post to say that you were clipping it off using bungee and a bolt snap. My chop buddies with the nerd don't have that.

Thanks for the pic.

ETA: can you see the HUD with it in the center? I find myself pushing the HUD out to the right side for visibility.

 

[stretchthepenn]

I didn't realize there was already a clip for the HUD, I (wrongly) interpreted your post to say that you were clipping it off using bungee and a bolt snap. My chop buddies with the nerd don't have that.

Thanks for the pic.

ETA: can you see the HUD with it in the center? I find myself pushing the HUD out to the right side for visibility.

You're welcome. In the left-hand photo, the HUD actually is bungeed; it's strapped to the nylon webbing that controls the top boltsnap; that may be the point of confusion.

RE: visibility -- I've not tried to dive with the HUD, as it and the NERD together are Las Vegas-neon overkill, but I can slide the mounting bracket left and right pretty far. I'm confident that I could find a spot where the HUD is visible.

 

[LFMarm]

Shut off on O2-no, just no no no. the bloody O2 tank is about 3 inches farther away than the shutoff would be, just turn the tank off.

One counter argument to keep the shut off valve — If you have solenoid failing open, you can close the in-line, keep the tank valve open and fly manual. If you don’t have the inline valve, you indeed need to close the tank valve and feather which I find less convenient.

 

[tbone1004]

One counter argument to keep the shut off valve — If you have solenoid failing open, you can close the in-line, keep the tank valve open and fly manual. If you don’t have the inline valve, you indeed need to close the tank valve and feather which I find less convenient.

I'm all about convenience of things to stay on the loop when stuff breaks, don't get me wrong. That said there are about 6 O2ptima CM divers that will ever be in a situation where you are going to actually really want to stay on the loop for the rest of the dive. Dive a hot dil, if the electronics work in SCR mode then you aren't using hardly any O2 anyway while you're at the bottom. If this is for an OW dive, leave the shutoff off and just bailout, it's good practice anyway.

 

[jlcnuke]

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.

My dive buddy is currently running the NERD as a monitor, and the Petrel 2 as the controller with no HUD. Slightly more work on assembly, but works fine. After getting some time on the unit, I think he's planning to drop the NERD completely and go to a standard HUD monitor and keep the Petrel 2 as the controller. I'll probably borrow his NERD for a few dives to see if it annoys me as much as it seems to bother him having it there in his face. If I like it, I'll probably buy it from him, but I honestly don't think I'm going to prefer it over the base setup I have (Petrel 2/HUD).

 

[Tracy]

Would like to get the experts opinion on which options to get with a new Optima CM. Here are the ones I identified so far:

• Nerd 2 as controller paired with HUD — no cables going to the wrist
• XT1 first stage — rotating turret
• Upgrade the ADV/MAV to a high flow quick disconnect QC-6 fitting —recommended for diving deeper than 40m
• pull dump to replace the bulky drysuit style dump for the counterlung
• Shut off on oxygen line

Do these make sense to you?

Nerd 2 is nice with the CM as it makes it self contained. That said, I am in the vast minority, I hate the Nerd. I have one, I never use it. I use a petrel controller on my BM and CM Optimas. Everybody is a bit different.

I like the XT1 because you can screw a transmitter directly into and do away with the short HP hoses that always leak. There isn't clearance for it with and FT1.

QC6 with the CM is again personal preference. I run one because I use it on other rebreathers that have BOVs and the rest of my team also uses it. If I was just running a CM with. DSV, it doesn't gain you anything.

Yes on the pull dump, I prefer it.

No on the oxygen shutoff, one more thing to forget that will kill you.

 

[stretchthepenn]

Nerd 2 is nice with the CM as it makes it self contained. That said, I am in the vast minority, I hate the Nerd. I have one, I never use it. I use a petrel controller on my BM and CM Optimas. Everybody is a bit different.

The NERD can get in the way a bit, but if you angle the thing correctly, it's not IN THE WAY.

Plus, one factor that's not been discussed (IIRC, I'm not reading the entire thread again to doublecheck) is readability for people who wear contacts/have corrective mask lenses. Sometimes I find my wrist computers hard to read, but the NERD's readout is always super-clear.

 

[Tracy]

The NERD can get in the way a bit, but if you angle the thing correctly, it's not IN THE WAY.

Plus, one factor that's not been discussed (IIRC, I'm not reading the entire thread again to doublecheck) is readability for people who wear contacts/have corrective mask lenses. Sometimes I find my wrist computers hard to read, but the NERD's readout is always super-clear.

For me, it is just a lot of information that I don't care about. I prefer a simple hud. As long as my PO2 is good, I really don't care about anything else on the screen. Should I need to know depth or time, I can look down and check it.

 

[LFMarm]

Thanks all for the great comments and contribution. Sharing here how I decided to set up my ChOptima for now:

• Using NERD 2 as controller paired with HUD — no cables going to the wrist
• FT1 first stage — no rotating turret but easy routing of hoses
• Upgraded the ADV/MAV to a high flow quick disconnect QC-6 fitting for diving deeper than 40m
• Kept the drysuit style dump for the counterlung as I found it very convenient to maintain minimum loop volume
• Kept the shut off on oxygen line so that I can fly in manual with the shut off closed in case of solenoid stuck open
• Added a bungee to connect the ChOptima to the crotch strap D-ring to keep it flush
• Substituted the high pressure hose from the O2 first stage with a longer one to improve the connection between transmitter and NERD (the Perdix has stable connection even with the factory hose but the NERD is having a hard time with that one and often loses connection)