Building A Chest Mounted Rebreather The O2ptima CM!

The Dive Rite O2ptima CM, AKA THE ChO2ptima, chest mounted rebreather an extremely versatile CCR! It works with your current Open Circuit configuration, be it Back-mounted single tank, doubles or even side-mount! In this video I'm going to discuss a few key points that make this unit the best on the market today! We are also going to build it from the ground up and show it in action! I hope you enjoy this video!
‪@GUEdivers‬ ​‪@DIVETALK‬ ‪@diverite84‬ ‪@DiversReady‬

[@niallmacleod1024]

Great video - thank you. I am qualifying across to the CM in the New Year so this is a helpful insight.

[@avramcollins6409]

This video was enjoyable to watch, detailed and interesting. I think your the 1st one to post a video like this on KZbin. I'm glad you did because I wanted to see an assembly on this rebreather for a while now. Can you post more videos of you diving this?

[@divecurrent]

🙏🏻 Thanks! I have other videos on this channel of me diving the unit. Take a look if you haven’t already. I’ll be posting many more!

[@avramcollins6409]

@@divecurrent cool, I'll check them out. Not sure why people aren't going crazy with this unit. Maybe cuz it's fairly new perhaps. Still, I like how you did a break down of this unit because no one else on you tube really had. I'm subscribed so I look forward to more videos.

[@adhamhwomble8345]

What is the max operating depth of this unit

[@azfiremedic120]

@@adhamhwomble8345 I know a guy that had had it down under 300'

[@kenmh7357]

Love the catridge

[@kenmh7357]

Looking at 3 CCRs for next year but this is the most compelling since is so travel ready.because I only dive in Mexico

[@mikesbigadventures194]

Nice video. Glad to see my head and water trap look the same (a little bit of white tribute here and there…). This is very good. Jared should use it…

[@divecurrent]

Thank you, I realize now that I missed a part, which I recorded but did not add. Checking the battery voltage…

[@mikesbigadventures194]

@@divecurrent Yeah. I didn’t realize you checked the sensors voltage twice

[@divecurrent]

@@mikesbigadventures194 we check the ambient air millivolts, then the millivolts with 02.

[@cliffordwilson9077]

Did you do a video review of all of your dive year set up, I noticed you had double 50s on your back

[@mikesbigadventures194]

@@cliffordwilson9077 That’s a standard set up with the Choptima. I dive that too. My other buddy dives a set of 50s sidemount. With a rebreather and a set of 40s for deco gas you have plenty of redundancy

[@OldManther]

Great video Steve. Do you use Molykote 111 on the pin connectors for the Nerd or HUD? If so, how often and how much are you using? That's what the manual recommends, but didn't see exactly where I should be applying it, how often and how much to use. Similar to Triblolube, I assume less is more (shiny not slimy), just not sure if it should be on the pins themselves or just on the rubber portion of the pins, etc.

[@billyleungkt]

Very nice video thks. Just wonder if you need to refill the scrubber in between dives. Do you need to disassemble and assemble again the whole unit and go through the checklist again?

[@divecurrent]

Yes…. Rebuild every time….

[@billyleungkt]

@@divecurrent that's quite troublesome. I guess it will take less time with more practice ☺️. Or shorten the dive time to have multiple dives a day. Right?

[@bill2292]

Great video! How much does a cartridge cost?

[@divecurrent]

$300 for 8

[@Mattieman1337]

Where did you get that metal mount for the NERD2?

[@divecurrent]

Back in 2021. That came from Dive Rite. It came with the unit

[@zachhoffman8514]

How does the diluant gas get into the bladder cause i didnt see the the way that the MAV would add the gas into the bladder. Im not rebreather certified so i also could just not know but im wondering

[@divecurrent]

Basically, you can manually add gas by pressing the MAV.. or once the counter lung becomes negative in pressure, It will pull diluent. It works similar to a second stage regulator.

[@zachhoffman8514]

@@divecurrent ok thank you. This helps to explain it better.

[@Smith6312]

Why not di-electric grease on the Dive-Can connections?

[@divecurrent]

The manufacturer recommends to put a small amount of trilube on the connectors to avoid corrosion.

[@sevenrider860]

Technically...Dow Corning Molykote 111 is the manufacturer recommended product for HUD and Controller Connector Lubrication as listed in the user manual. I don't like to deal with two different lubricants when assembling, so I use Tribolube 71 also.

[@divecurrent]

@@sevenrider860 exactly 👌

[@MDWtubeChannel]

Why not run the Nerd on the left and HUD on the right so you don't have to cross the cables at the bottom to get to the correct canister for each and so the HUD is not upside down when mounted to the DSV?

[@divecurrent]

The HUD is for redundancy and available only when needed. Also, it is flipped and set for the left side by changing settings. I stow it away until then. As for the Nerd controller, I’m right eye dominant and it’s natural to have the controller on my right. The cables crossed are not an issue. It’s actually nice to cross and have them tucked away. This is setup for my purposes, that’s what makes it so nice. You can set it up for the individual 👌

[@DZ4295DBW]

Will this work with the Kirby Morgan Mod-1 combat diver mask?

[@alfonsobetancort]

Rebreathers are still very primitive, like looking at dive gear from 1950. I hope that a big brand invests and develops a system according to XXI technology that does not look like a weekend DIY project.

[@bonnie31419]

Why was the NERD readings .93 after you calibrated at 1.0 .. then HUD calibrated at 1.0 correctly

[@rhansen721]

Good question. 100% oxygen will only read a PO2 of 1.00 when at sea level. It's still 100% oxygen at higher elevations; however, the PO2 reading will decrease with elevation. For example, I live at at a 1200 foot elevation, and I get .95 to .96 PO2 readings on my Petrel when calibrating. Both the NERD and Petrel are designed to account for elevation, while the HUD by itself is not. I'm guessing that the HUD sees the .93 as close enough to 1.00 that it just rounds-up to 1.00. I know on my Meg unit that I can plug the Petrel into the HUD connector, and the HUD into the Petrel connector, and this will allow the HUD to read the true elevation via the Petrel. It's really not necessary at lower elevations. If I lived in Denver, then I would probably go the extra step. At the end of the day, you should be holding a setpoint so that your PO2 is well away from the low end of .16, and the high end of 1.6. If you're at a setpoint of 0.7, and your HUD is reading 0.8, life is still good.

[@travismcelveen5172]

@@rhansen721 You can clearly see on the NERD that it's using .95 ata as ambient pressure. You can also see that the NERD is set to calibrate O2 at 98% (not 100%). So .95 x .98 = .93. The HUD is permanently set to calibrate O2 at 100% which will explain the different readings between NERD and HUD. For this reason, I always set my controller to calculate O2 at 100% so it always matches my HUD.

[@user-ru1yg2ig5y]

Sorry but I don't get it, maybe because I'm not a rebreather diver. But I have a question after seeing carefully every second of your video. Where is the diluent gas tank? I mean, it can't operate only on an oxygen tank, right?

[@user-ru1yg2ig5y]

An answer on that ? 👆

[@jeffmark2927]

You can use backmounted tanks( single or doubles) or sidemount for your diluent and bailout. It is whatever you are comfortable with diving.

[@user-ru1yg2ig5y]

@@jeffmark2927 so the system uses a sidemount as a diluent and as a bailout at the same time... Very interesting and minimalistic!!

[@jeffmark2927]

@@user-ru1yg2ig5y Exactly.Simple and compact.

[@stinksterrekerinski4450]

Chest mount might be the future. Smallness is a factor on how quick it becomes popular.

[@divecurrent]

I disagree, there is always going to be a need for a back-mounted unit. It's simply a tool for a job. It doesn't work for everyone.

[@MDWtubeChannel]

I assume you are showing here first time assembly only. It seems unnecessary to have to run the cables through the lung pouch, install the hoses to the head, remove and reinstall the sensor holder, etc. every time you put it back together after cleaning. All those things should be able to remain assembled without impacting your ability to clean what needs to be cleaned and saves time on reassembly, right?

[@divecurrent]

I’m going to make making another video about break down and cleaning which will answer your questions then in more detail. The manufacturer recommends the unit is disassembled and put together before every dive (not repetitive same day dives) to ensure all parts are in working order. We inspect every O-ring and every part before every dive just to be safe. The risk is not worth saving a couple minutes of build time in my estimation. As far as the cables. The DSV and hoses need to be taken apart and cleaned after every dive and inspected before the dive anyway. The nerd and HUD have to be removed. It takes no time to run the wires through the bag so I’m not really seeing any issue there.

[@avramcollins6409]

Also, is the nerd not bothersome as compared to a wrist mount?

[@divecurrent]

The nerd isn’t bothersome at all. It’s positioned low enough where it’s doesn’t inhibit my field of view too bad. It’s amazing how much better it is to have the controller at my eye. All the info is right there compared to being on my wrist.

[@avramcollins6409]

@@divecurrent thanks for that insight, not sure if people just get stuck with that option upon arrival of their unit but it seemed impeding from an outside perspective. Good to know all this info your pushing out, I love geeking out to this shit til my nose bleeds.

[@jeffmark2927]

It's nice not having wires running down your arm, especially if you are going inside a wreck.

[@travismcelveen5172]

Why does it matter which way the EAC is facing?

[@divecurrent]

great question, the EAC must be used in the same direction always because when the cartridge filters out the CO2, it's not evenly doing so. If you were to flip it, you would eventually have a CO2 hit because used portion of the EAC would not be able to filter.

[@travismcelveen5172]

​@@divecurrent That's not how the EAC works. The cartridge will absorb the same amount of CO2 regardless of the orientation of the cartridge. As the EAC gets "used up" gas continues to flow and gets absorbed downstream until the EAC reaches capacity.

[@tonykomery7991]

It seems very complicated, to many electronics could go wrong, I would not want to have a problem when I am at great depth. I will stick to SCUBA. Thank you for this video.

[@divecurrent]

The electronics are a necessity and work great if you maintain and monitor them. Keep in mind, you can also shut off the electronics and run it manual if/when needed. 👌