Review Scubatron GBM Chest Mount nCCR

[Fat old english bloke]

None of the above rebreathers would be beneficial. I want something with minimum training, and as an add on to open circuit. I'm not certified at the moment, although I have long term plans to participate in technical diving. So my choices need to be accurate.

I think you should set-aside any plans to get a CCR for a good while.

 

[AJ]

I was thinking the chest mounted rebreathers could be as simple as open circuit training without the extra luggage of technical diving.

A rebreather is still a rebreather. There's no such thing as a simple rebreather. It does not matter where and how you put it. Rebreathers are complex machines that require a lot of dedication.

I have received a few option's on chest mounted rebreathers. Most of my future diving will be open circuit. Some are telling me you don't need one if I'm not diving deep.

Stay with OC until you really need a rebreather for the kind of diving you want to do. I really enjoy my simple OC dives more then doing those with a CCR. However, deco diving deep wrecks is imho not a enjoyable with OC as with a rebreather. Besides the cost of trimix gas, rebreathers are more practical for more complex dives.

 

[missionmtb]

Do you see yourself dropping the final galvanic at some point? Did you do any unit specific training?

I will probably go all SSS eventually. This unit is certified to be taught under IANTD and I did a cross-over course with them.

 

[missionmtb]

Recently got a question on breathing resistance for the GBM, here's what I've learned:

"I've gotten my GBM to behave by being mindful to allow the counterlungs to take their cube shape. Things that can prevent this are:
1. under-inflated counterlungs - keep a little more than minimum loop in there. Add lead if necessary, especially while you're messing with it. This can feel like what a wet or partially flooded scrubber feels like on a backmount, it's just the bag bunching up against the port probably and making any accumulated fluid make noise.
2. Torque from too short of hoses on the ADV and MAV inlets - run some extra hose length so the elbows are free to rotate to any position.
3. Torque from the DSV - adjust those elbows until the ADV/OPV are sitting totally neutral and don't want to torque up or down.
4. Get your unit flat against your chest - if it rides up at all it can fold the unit over and prevent the counterlungs from being the right shape. I have bungees pulling down from the bottom of my backplate to stretch the unit flat against my chests.
5. Make absolutely sure the p-port and elbows are not twisting the counterlung during assembly - if you see any wrinkles or the counterlungs aren't taking their happy cube shape, twist the fittings until they do. The elbows and p-ports should all be in-plane with each other. The p-port tubes need to be equidistant from the front and back of the case.
6. Ride the unit high - on the boat I have to pull the D-rings on my shoulder straps down to get the clips to reach and my unit is centered on my drysuit inflator. The higher the better. It's a chest mount, not a belly mount rebreather."

Happy diving,
M

 

[grantmac]

It's been almost a year and we no longer have the AI Bot to derail. How is the long term experience on this unit?

 

[missionmtb]

It's been almost a year and we no longer have the AI Bot to derail. How is the long term experience on this unit?

I'm at about 150 hours on the unit and am still really pleased with it!

Since we last checked in:
1. Scubatron has updated my early MAV block to their latest version with a much larger knob and more flow adjustability (several LPM?!), better spacing between QD posts. The ergonomics are much better and it's not made out of white POM anymore, slick!
2. I've swapped the velcro straps on the cylinder for proper dive rite cam buckles. I've also installed a little fairlead that goes between the straps to help keep my DPV tow cord inline. Big improvement in terms of stability and useability.
3. I'm all in on the solid state sensors for my primary and have been very pleased with their performance. My first 5-6 cells were from an early lot apparently and had to be replaced. The current set are flawless. I'm much better about keeping them dark while stored too, so batteries are lasting longer. You can really see the galvanic degrade over time when compared to the rock-solid SSS.
4. I got rid of the QD and check valve on the right elbow to get rid of the honking, praise be! Now the hose running from the mix-out on the MAV block is hard connected to the elbow and totally silent. I can sneak up on people again!
5. I've swapped both hoses that connect to the elbows back to flex hoses, this has helped remove torque on the elbows that was collapsing the counterlungs. I think this has been the biggest improvement in breathing effort overall (I think this was the OG configuration, doh).
6. I designed an adapter block to attach the original Shearwater NERD bracket to the DSV, reasonably happy with it.

There's a new integrated elbow/MAV available, a mini canister to compete with the likes of the base DTG, but I feel my unit is missing nothing.

Getting ready to do another monster dive out here with my trusty GBM in a week, feeling confident.

 

[grantmac]

Details on the mini can? That's a very appealing addition if I'm honest.

The shear amount of water traps on this has it seeming like a big leg up on the DTG.

 

[missionmtb]

Details on the mini can? That's a very appealing addition if I'm honest.

The shear amount of water traps on this has it seeming like a big leg up on the DTG.

From facebook, it's called the RTD20 for ready to dive 20 total pounds and has a 3 instead of 5 lb. scrubber.

Agree, its ability to trap water/drool is really good